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2019-03-14tracing/probe: Verify alloc_trace_*probe() resultMasami Hiramatsu
Since alloc_trace_*probe() returns -EINVAL only if !event && !group, it should not happen in trace_*probe_create(). If we catch that case there is a bug. So use WARN_ON_ONCE() instead of pr_info(). Link: http://lkml.kernel.org/r/155253785078.14922.16902223633734601469.stgit@devnote2 Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-03-14tracing/probe: Check event/group naming rule at parsingMasami Hiramatsu
Check event and group naming rule at parsing it instead of allocating probes. Link: http://lkml.kernel.org/r/155253784064.14922.2336893061156236237.stgit@devnote2 Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-03-14tracing/probe: Check the size of argument name and bodyMasami Hiramatsu
Check the size of argument name and expression is not 0 and smaller than maximum length. Link: http://lkml.kernel.org/r/155253783029.14922.12650939303827581096.stgit@devnote2 Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-03-14tracing/probe: Check event name length correctlyMasami Hiramatsu
Ensure given name of event is not too long when parsing it, and fix to update event name offset correctly when the group name is given. For example, this makes probe event to check the "p:foo/" error case correctly. Link: http://lkml.kernel.org/r/155253782046.14922.14724124823730168629.stgit@devnote2 Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-03-14tracing/probe: Check maxactive error casesMasami Hiramatsu
Check maxactive on kprobe error case, because maxactive is only for kretprobe, not for kprobe. Also, maxactive should not be 0, it should be at least 1. Link: http://lkml.kernel.org/r/155253780952.14922.15784129810238750331.stgit@devnote2 Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-03-13tracing: kdb: Fix ftdump to not sleepDouglas Anderson
As reported back in 2016-11 [1], the "ftdump" kdb command triggers a BUG for "sleeping function called from invalid context". kdb's "ftdump" command wants to call ring_buffer_read_prepare() in atomic context. A very simple solution for this is to add allocation flags to ring_buffer_read_prepare() so kdb can call it without triggering the allocation error. This patch does that. Note that in the original email thread about this, it was suggested that perhaps the solution for kdb was to either preallocate the buffer ahead of time or create our own iterator. I'm hoping that this alternative of adding allocation flags to ring_buffer_read_prepare() can be considered since it means I don't need to duplicate more of the core trace code into "trace_kdb.c" (for either creating my own iterator or re-preparing a ring allocator whose memory was already allocated). NOTE: another option for kdb is to actually figure out how to make it reuse the existing ftrace_dump() function and totally eliminate the duplication. This sounds very appealing and actually works (the "sr z" command can be seen to properly dump the ftrace buffer). The downside here is that ftrace_dump() fully consumes the trace buffer. Unless that is changed I'd rather not use it because it means "ftdump | grep xyz" won't be very useful to search the ftrace buffer since it will throw away the whole trace on the first grep. A future patch to dump only the last few lines of the buffer will also be hard to implement. [1] https://lkml.kernel.org/r/20161117191605.GA21459@google.com Link: http://lkml.kernel.org/r/20190308193205.213659-1-dianders@chromium.org Reported-by: Brian Norris <briannorris@chromium.org> Signed-off-by: Douglas Anderson <dianders@chromium.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-03-12trace/probes: Remove kernel doc style from non kernel doc commentValdis Klētnieks
CC kernel/trace/trace_kprobe.o kernel/trace/trace_kprobe.c:41: warning: cannot understand function prototype: 'struct trace_kprobe ' The real problem is that a comment looked like kerneldoc when it shouldn't be... Link: http://lkml.kernel.org/r/2812.1552381112@turing-police Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-03-12tracing/probes: Make reserved_field_names staticValdis Klētnieks
sparse complains: CHECK kernel/trace/trace_probe.c kernel/trace/trace_probe.c:16:12: warning: symbol 'reserved_field_names' was not declared. Should it be static? Yes, it should be static. Link: http://lkml.kernel.org/r/2478.1552380778@turing-police Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-03-05tracing: Use strncpy instead of memcpy when copying comm in trace.cTom Zanussi
Because there may be random garbage beyond a string's null terminator, code that might use the entire comm array e.g. histogram keys, can give unexpected results if that garbage is copied in too, so avoid that possibility by using strncpy instead of memcpy. Link: http://lkml.kernel.org/r/1d6ebac26570c2a29ce9fb575379f17ef5c8b81b.1551802084.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Suggested-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-03-05tracing: Use strncpy instead of memcpy when copying comm for hist triggersTom Zanussi
Because there may be random garbage beyond a string's null terminator, code that might use the entire comm array e.g. histogram keys, can give unexpected results if that garbage is copied in too, so avoid that possibility by using strncpy instead of memcpy. Link: http://lkml.kernel.org/r/1eb9f096a8086c3c82c7fc087c900005143cec54.1551802084.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-03-05tracing: Use strncpy instead of memcpy for string keys in hist triggersTom Zanussi
Because there may be random garbage beyond a string's null terminator, it's not correct to copy the the complete character array for use as a hist trigger key. This results in multiple histogram entries for the 'same' string key. So, in the case of a string key, use strncpy instead of memcpy to avoid copying in the extra bytes. Before, using the gdbus entries in the following hist trigger as an example: # echo 'hist:key=comm' > /sys/kernel/debug/tracing/events/sched/sched_waking/trigger # cat /sys/kernel/debug/tracing/events/sched/sched_waking/hist ... { comm: ImgDecoder #4 } hitcount: 203 { comm: gmain } hitcount: 213 { comm: gmain } hitcount: 216 { comm: StreamTrans #73 } hitcount: 221 { comm: mozStorage #3 } hitcount: 230 { comm: gdbus } hitcount: 233 { comm: StyleThread#5 } hitcount: 253 { comm: gdbus } hitcount: 256 { comm: gdbus } hitcount: 260 { comm: StyleThread#4 } hitcount: 271 ... # cat /sys/kernel/debug/tracing/events/sched/sched_waking/hist | egrep gdbus | wc -l 51 After: # cat /sys/kernel/debug/tracing/events/sched/sched_waking/hist | egrep gdbus | wc -l 1 Link: http://lkml.kernel.org/r/50c35ae1267d64eee975b8125e151e600071d4dc.1549309756.git.tom.zanussi@linux.intel.com Cc: Namhyung Kim <namhyung@kernel.org> Cc: stable@vger.kernel.org Fixes: 79e577cbce4c4 ("tracing: Support string type key properly") Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-03-05tracing: Use str_has_prefix() in synth_event_create()Tom Zanussi
Since we now have a str_has_prefix() that returns the length, we can use that instead of explicitly calculating it. Link: http://lkml.kernel.org/r/03418373fd1e80030e7394b8e3e081c5de28a710.1549309756.git.tom.zanussi@linux.intel.com Cc: Joe Perches <joe@perches.com> Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-21tracing/perf: Use strndup_user() instead of buggy open-coded versionJann Horn
The first version of this method was missing the check for `ret == PATH_MAX`; then such a check was added, but it didn't call kfree() on error, so there was still a small memory leak in the error case. Fix it by using strndup_user() instead of open-coding it. Link: http://lkml.kernel.org/r/20190220165443.152385-1-jannh@google.com Cc: Ingo Molnar <mingo@kernel.org> Cc: stable@vger.kernel.org Fixes: 0eadcc7a7bc0 ("perf/core: Fix perf_uprobe_init()") Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-20tracing: Fix spelling mistake: "analagous" -> "analogous"Colin Ian King
There is a spelling mistake in the mini-howto help text. Fix it. Link: http://lkml.kernel.org/r/20190217223222.16479-1-colin.king@canonical.com Signed-off-by: Colin Ian King <colin.king@canonical.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-20tracing: Comment why cond_snapshot is checked outside of max_lock protectionSteven Rostedt (VMware)
Before setting tr->cond_snapshot, it must be NULL before it can be updated. It can go to NULL when a trace event hist trigger is created or removed, and can only be modified under the max_lock spin lock. But because it can only be set to something other than NULL under both the max_lock spin lock as well as the trace_types_lock, we can perform the check if it is not NULL only under the trace_types_lock and fail out without having to grab the max_lock spin lock. This is very subtle, and deserves a comment. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-20tracing: Add alternative synthetic event trace action syntaxTom Zanussi
Add a 'trace(synthetic_event_name, params)' alternative to synthetic_event_name(params). Currently, the syntax used for generating synthetic events is to invoke synthetic_event_name(params) i.e. use the synthetic event name as a function call. Users requested a new form that more explicitly shows that the synthetic event is in effect being traced. In this version, a new 'trace()' keyword is used, and the synthetic event name is passed in as the first argument. In addition, for the sake of consistency with other actions, change the documention to emphasize the trace() form over the function-call form, which remains documented as equivalent. Link: http://lkml.kernel.org/r/d082773e50232a001480cf837679a1e01c1a2eb7.1550100284.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-20tracing: Add hist trigger onchange() handlerTom Zanussi
Add support for a hist:onchange($var) handler, similar to the onmax() handler but triggering whenever there's any change in $var, not just a max. Link: http://lkml.kernel.org/r/dfbc7e4ada242603e9ec3f049b5ad076a07dfd03.1550100284.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-20tracing: Add hist trigger snapshot() actionTom Zanussi
Add support for hist:handlerXXX($var).snapshot(), which will take a snapshot of the current trace buffer whenever handlerXXX is hit. As a first user, this also adds snapshot() action support for the onmax() handler i.e. hist:onmax($var).snapshot(). Also, the hist trigger key printing is moved into a separate function so the snapshot() action can print a histogram key outside the histogram display - add and use hist_trigger_print_key() for that purpose. Link: http://lkml.kernel.org/r/2f1a952c0dcd8aca8702ce81269581a692396d45.1550100284.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-20tracing: Add conditional snapshotTom Zanussi
Currently, tracing snapshots are context-free - they capture the ring buffer contents at the time the tracing_snapshot() function was invoked, and nothing else. Additionally, they're always taken unconditionally - the calling code can decide whether or not to take a snapshot, but the data used to make that decision is kept separately from the snapshot itself. This change adds the ability to associate with each trace instance some user data, along with an 'update' function that can use that data to determine whether or not to actually take a snapshot. The update function can then update that data along with any other state (as part of the data presumably), if warranted. Because snapshots are 'global' per-instance, only one user can enable and use a conditional snapshot for any given trace instance. To enable a conditional snapshot (see details in the function and data structure comments), the user calls tracing_snapshot_cond_enable(). Similarly, to disable a conditional snapshot and free it up for other users, tracing_snapshot_cond_disable() should be called. To actually initiate a conditional snapshot, tracing_snapshot_cond() should be called. tracing_snapshot_cond() will invoke the update() callback, allowing the user to decide whether or not to actually take the snapshot and update the user-defined data associated with the snapshot. If the callback returns 'true', tracing_snapshot_cond() will then actually take the snapshot and return. This scheme allows for flexibility in snapshot implementations - for example, by implementing slightly different update() callbacks, snapshots can be taken in situations where the user is only interested in taking a snapshot when a new maximum in hit versus when a value changes in any way at all. Future patches will demonstrate both cases. Link: http://lkml.kernel.org/r/1bea07828d5fd6864a585f83b1eed47ce097eb45.1550100284.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-20tracing: Generalize hist trigger onmax and save actionTom Zanussi
The action refactor code allowed actions and handlers to be separated, but the existing onmax handler and save action code is still not flexible enough to handle arbitrary coupling. This change generalizes them and in the process makes additional handlers and actions easier to implement. The onmax action can be broken up and thought of as two separate components - a variable to be tracked (the parameter given to the onmax($var_to_track) function) and an invisible variable created to save the ongoing result of doing something with that variable, such as saving the max value of that variable so far seen. Separating it out like this and renaming it appropriately allows us to use the same code for similar tracking functions such as onchange($var_to_track), which would just track the last value seen rather than the max seen so far, which is useful in some situations. Additionally, because different handlers and actions may want to save and access data differently e.g. save and retrieve tracking values as local variables vs something more global, save_val() and get_val() interface functions are introduced and max-specific implementations are used instead. The same goes for the code that checks whether a maximum has been hit - a generic check_val() interface and max-checking implementation is used instead, which allows future patches to make use of he same code using their own implemetations of similar functionality. Link: http://lkml.kernel.org/r/980ea73dd8e3f36db3d646f99652f8fed42b77d4.1550100284.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-20tracing: Split up onmatch action dataTom Zanussi
Currently, the onmatch action data binds the onmatch action to data related to synthetic event generation. Since we want to allow the onmatch handler to potentially invoke a different action, and because we expect other handlers to generate synthetic events, we need to separate the data related to these two functions. Also rename the onmatch data to something more descriptive, and create and use common action data destroy function. Link: http://lkml.kernel.org/r/b9abbf9aae69fe3920cdc8ddbcaad544dd258d78.1550100284.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-20tracing: Refactor hist trigger action codeTom Zanussi
The hist trigger action code currently implements two essentially hard-coded pairs of 'actions' - onmax(), which tracks a variable and saves some event fields when a max is hit, and onmatch(), which is hard-coded to generate a synthetic event. These hardcoded pairs (track max/save fields and detect match/generate synthetic event) should really be decoupled into separate components that can then be arbitrarily combined. The first component of each pair (track max/detect match) is called a 'handler' in the new code, while the second component (save fields/generate synthetic event) is called an 'action' in this scheme. This change refactors the action code to reflect this split by adding two handlers, HANDLER_ONMATCH and HANDLER_ONMAX, along with two actions, ACTION_SAVE and ACTION_TRACE. The new code combines them to produce the existing ONMATCH/TRACE and ONMAX/SAVE functionality, but doesn't implement the other combinations now possible. Future patches will expand these to further useful cases, such as ONMAX/TRACE, as well as add additional handlers and actions such as ONCHANGE and SNAPSHOT. Also, add abbreviated documentation for handlers and actions to README. Link: http://lkml.kernel.org/r/98bfdd48c1b4ff29fc5766442f99f5bc3c34b76b.1550100284.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-20tracing: Do not free iter->trace in fail path of tracing_open_pipe()zhangyi (F)
Commit d716ff71dd12 ("tracing: Remove taking of trace_types_lock in pipe files") use the current tracer instead of the copy in tracing_open_pipe(), but it forget to remove the freeing sentence in the error path. There's an error path that can call kfree(iter->trace) after the iter->trace was assigned to tr->current_trace, which would be bad to free. Link: http://lkml.kernel.org/r/1550060946-45984-1-git-send-email-yi.zhang@huawei.com Cc: stable@vger.kernel.org Fixes: d716ff71dd12 ("tracing: Remove taking of trace_types_lock in pipe files") Signed-off-by: zhangyi (F) <yi.zhang@huawei.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-15uprobes: convert uprobe.ref to refcount_tElena Reshetova
atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable uprobe.ref is used as pure reference counter. Convert it to refcount_t and fix up the operations. **Important note for maintainers: Some functions from refcount_t API defined in lib/refcount.c have different memory ordering guarantees than their atomic counterparts. The full comparison can be seen in https://lkml.org/lkml/2017/11/15/57 and it is hopefully soon in state to be merged to the documentation tree. Normally the differences should not matter since refcount_t provides enough guarantees to satisfy the refcounting use cases, but in some rare cases it might matter. Please double check that you don't have some undocumented memory guarantees for this variable usage. For the uprobe.ref it might make a difference in following places: - put_uprobe(): decrement in refcount_dec_and_test() only provides RELEASE ordering and control dependency on success vs. fully ordered atomic counterpart Link: http://lkml.kernel.org/r/1547637627-29526-1-git-send-email-elena.reshetova@intel.com Suggested-by: Kees Cook <keescook@chromium.org> Acked-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-15ftrace: Allow enabling of filters via index of available_filter_functionsSteven Rostedt (VMware)
Enabling of large number of functions by echoing in a large subset of the functions in available_filter_functions can take a very long time. The process requires testing all functions registered by the function tracer (which is in the 10s of thousands), and doing a kallsyms lookup to convert the ip address into a name, then comparing that name with the string passed in. When a function causes the function tracer to crash the system, a binary bisect of the available_filter_functions can be done to find the culprit. But this requires passing in half of the functions in available_filter_functions over and over again, which makes it basically a O(n^2) operation. With 40,000 functions, that ends up bing 1,600,000,000 opertions! And enabling this can take over 20 minutes. As a quick speed up, if a number is passed into one of the filter files, instead of doing a search, it just enables the function at the corresponding line of the available_filter_functions file. That is: # echo 50 > set_ftrace_filter # cat set_ftrace_filter x86_pmu_commit_txn # head -50 available_filter_functions | tail -1 x86_pmu_commit_txn This allows setting of half the available_filter_functions to take place in less than a second! # time seq 20000 > set_ftrace_filter real 0m0.042s user 0m0.005s sys 0m0.015s # wc -l set_ftrace_filter 20000 set_ftrace_filter Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-11tracing: Change the function format to display function names by perfChangbin Du
Here is an example for this change. $ sudo perf record -e 'ftrace:function' --filter='ip==schedule' $ sudo perf report The output of perf before this patch: \# Samples: 100 of event 'ftrace:function' \# Event count (approx.): 100 \# \# Overhead Trace output \# ........ ...................................... \# 51.00% ffffffff81f6aaa0 <-- ffffffff81158e8d 29.00% ffffffff81f6aaa0 <-- ffffffff8116ccb2 8.00% ffffffff81f6aaa0 <-- ffffffff81f6f2ed 4.00% ffffffff81f6aaa0 <-- ffffffff811628db 4.00% ffffffff81f6aaa0 <-- ffffffff81f6ec5b 2.00% ffffffff81f6aaa0 <-- ffffffff81f6f21a 1.00% ffffffff81f6aaa0 <-- ffffffff811b04af 1.00% ffffffff81f6aaa0 <-- ffffffff8143ce17 After this patch: \# Samples: 36 of event 'ftrace:function' \# Event count (approx.): 36 \# \# Overhead Trace output \# ........ ............................................ \# 38.89% schedule <-- schedule_hrtimeout_range_clock 27.78% schedule <-- worker_thread 13.89% schedule <-- schedule_timeout 11.11% schedule <-- smpboot_thread_fn 5.56% schedule <-- rcu_gp_kthread 2.78% schedule <-- exit_to_usermode_loop Link: http://lkml.kernel.org/r/20190209161919.32350-1-changbin.du@gmail.com Signed-off-by: Changbin Du <changbin.du@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-06ring-buffer: Remove unused function ring_buffer_page_len()Miroslav Benes
Commit 6b7e633fe9c2 ("tracing: Remove extra zeroing out of the ring buffer page") removed the only caller of ring_buffer_page_len(). The function is now unused and may be removed. Link: http://lkml.kernel.org/r/20181228133847.106177-1-mbenes@suse.cz Signed-off-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-06tracing: Show stacktrace for wakeup tracersChangbin Du
This align the behavior of wakeup tracers with irqsoff latency tracer that we record stacktrace at the beginning and end of waking up. The stacktrace shows us what is happening in the kernel. Link: http://lkml.kernel.org/r/20190116160249.7554-1-changbin.du@gmail.com Signed-off-by: Changbin Du <changbin.du@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-06tracing: Put a margin between flags and duration for wakeup tracersChangbin Du
Don't mix context flags with function duration info. Instead of this: # tracer: wakeup_rt # # wakeup_rt latency trace v1.1.5 on 5.0.0-rc1-test+ # -------------------------------------------------------------------- # latency: 177 us, #545/545, CPU#0 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:8) # ----------------- # | task: migration/0-11 (uid:0 nice:0 policy:1 rt_prio:99) # ----------------- # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / # REL TIME CPU TASK/PID |||| DURATION FUNCTION CALLS # | | | | |||| | | | | | | 0 us | 0) <idle>-0 | dNh5 | /* 0:120:R + [000] 11: 0:R migration/0 */ 2 us | 0) <idle>-0 | dNh5 0.000 us | (null)(); 4 us | 0) <idle>-0 | dNh4 | _raw_spin_unlock() { 4 us | 0) <idle>-0 | dNh4 0.304 us | preempt_count_sub(); 5 us | 0) <idle>-0 | dNh3 1.063 us | } 5 us | 0) <idle>-0 | dNh3 0.266 us | ttwu_stat(); 6 us | 0) <idle>-0 | dNh3 | _raw_spin_unlock_irqrestore() { 6 us | 0) <idle>-0 | dNh3 0.273 us | preempt_count_sub(); 6 us | 0) <idle>-0 | dNh2 0.818 us | } Show this: # tracer: wakeup # # wakeup latency trace v1.1.5 on 4.20.0+ # -------------------------------------------------------------------- # latency: 593 us, #674/674, CPU#0 | (M:desktop VP:0, KP:0, SP:0 HP:0 #P:4) # ----------------- # | task: kworker/0:1H-339 (uid:0 nice:-20 policy:0 rt_prio:0) # ----------------- # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / # REL TIME CPU TASK/PID |||| DURATION FUNCTION CALLS # | | | | |||| | | | | | | 0 us | 0) <idle>-0 | dNs. | | /* 0:120:R + [000] 339:100:R kworker/0:1H */ 3 us | 0) <idle>-0 | dNs. | 0.000 us | (null)(); 67 us | 0) <idle>-0 | dNs. | 0.721 us | ttwu_stat(); 69 us | 0) <idle>-0 | dNs. | 0.607 us | _raw_spin_unlock_irqrestore(); 71 us | 0) <idle>-0 | .Ns. | 0.598 us | _raw_spin_lock_irq(); 72 us | 0) <idle>-0 | .Ns. | 0.584 us | _raw_spin_lock_irq(); 73 us | 0) <idle>-0 | dNs. | + 11.118 us | __next_timer_interrupt(); 75 us | 0) <idle>-0 | dNs. | | call_timer_fn() { 76 us | 0) <idle>-0 | dNs. | | delayed_work_timer_fn() { 76 us | 0) <idle>-0 | dNs. | | __queue_work() { ... Link: http://lkml.kernel.org/r/20190101154614.8887-4-changbin.du@gmail.com Signed-off-by: Changbin Du <changbin.du@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-06tracing: Show more info for funcgraph wakeup tracersChangbin Du
Add these info fields to funcgraph wakeup tracers: o Show CPU info since the waker could be on a different CPU. o Show function duration and overhead. o Show IRQ markers. Link: http://lkml.kernel.org/r/20190101154614.8887-3-changbin.du@gmail.com Signed-off-by: Changbin Du <changbin.du@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-06tracing: Add comment to predicate_parse() about "&&" or "||"Steven Rostedt (VMware)
As the predicat_parse() code is rather complex, commenting subtleties is important. The switch case statement should be commented to describe that it is only looking for two '&' or '|' together, which is why the fall through to an error is after the check. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-06tracing: Annotate implicit fall through in predicate_parse()Mathieu Malaterre
There is a plan to build the kernel with -Wimplicit-fallthrough and this place in the code produced a warning (W=1). This commit remove the following warning: kernel/trace/trace_events_filter.c:494:8: warning: this statement may fall through [-Wimplicit-fallthrough=] Link: http://lkml.kernel.org/r/20190114203039.16535-2-malat@debian.org Signed-off-by: Mathieu Malaterre <malat@debian.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-06tracing: Annotate implicit fall through in parse_probe_arg()Mathieu Malaterre
There is a plan to build the kernel with -Wimplicit-fallthrough and this place in the code produced a warning (W=1). This commit remove the following warning: kernel/trace/trace_probe.c:302:6: warning: this statement may fall through [-Wimplicit-fallthrough=] Link: http://lkml.kernel.org/r/20190114203039.16535-1-malat@debian.org Signed-off-by: Mathieu Malaterre <malat@debian.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-06function_graph: Support displaying relative timestampChangbin Du
When function_graph is used for latency tracers, relative timestamp is more straightforward than absolute timestamp as function trace does. This change adds relative timestamp support to function_graph and applies to latency tracers (wakeup and irqsoff). Instead of: # tracer: irqsoff # # irqsoff latency trace v1.1.5 on 5.0.0-rc1-test # -------------------------------------------------------------------- # latency: 521 us, #1125/1125, CPU#2 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:8) # ----------------- # | task: swapper/2-0 (uid:0 nice:0 policy:0 rt_prio:0) # ----------------- # => started at: __schedule # => ended at: _raw_spin_unlock_irq # # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / # TIME CPU TASK/PID |||| DURATION FUNCTION CALLS # | | | | |||| | | | | | | 124.974306 | 2) systemd-693 | d..1 0.000 us | __schedule(); 124.974307 | 2) systemd-693 | d..1 | rcu_note_context_switch() { 124.974308 | 2) systemd-693 | d..1 0.487 us | rcu_preempt_deferred_qs(); 124.974309 | 2) systemd-693 | d..1 0.451 us | rcu_qs(); 124.974310 | 2) systemd-693 | d..1 2.301 us | } [..] 124.974826 | 2) <idle>-0 | d..2 | finish_task_switch() { 124.974826 | 2) <idle>-0 | d..2 | _raw_spin_unlock_irq() { 124.974827 | 2) <idle>-0 | d..2 0.000 us | _raw_spin_unlock_irq(); 124.974828 | 2) <idle>-0 | d..2 0.000 us | tracer_hardirqs_on(); <idle>-0 2d..2 552us : <stack trace> => __schedule => schedule_idle => do_idle => cpu_startup_entry => start_secondary => secondary_startup_64 Show: # tracer: irqsoff # # irqsoff latency trace v1.1.5 on 5.0.0-rc1-test+ # -------------------------------------------------------------------- # latency: 511 us, #1053/1053, CPU#7 | (M:preempt VP:0, KP:0, SP:0 HP:0 #P:8) # ----------------- # | task: swapper/7-0 (uid:0 nice:0 policy:0 rt_prio:0) # ----------------- # => started at: __schedule # => ended at: _raw_spin_unlock_irq # # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / # REL TIME CPU TASK/PID |||| DURATION FUNCTION CALLS # | | | | |||| | | | | | | 0 us | 7) sshd-1704 | d..1 0.000 us | __schedule(); 1 us | 7) sshd-1704 | d..1 | rcu_note_context_switch() { 1 us | 7) sshd-1704 | d..1 0.611 us | rcu_preempt_deferred_qs(); 2 us | 7) sshd-1704 | d..1 0.484 us | rcu_qs(); 3 us | 7) sshd-1704 | d..1 2.599 us | } [..] 509 us | 7) <idle>-0 | d..2 | finish_task_switch() { 510 us | 7) <idle>-0 | d..2 | _raw_spin_unlock_irq() { 510 us | 7) <idle>-0 | d..2 0.000 us | _raw_spin_unlock_irq(); 512 us | 7) <idle>-0 | d..2 0.000 us | tracer_hardirqs_on(); <idle>-0 7d..2 543us : <stack trace> => __schedule => schedule_idle => do_idle => cpu_startup_entry => start_secondary => secondary_startup_64 Link: http://lkml.kernel.org/r/20190101154614.8887-2-changbin.du@gmail.com Signed-off-by: Changbin Du <changbin.du@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2019-02-03Merge branch 'smp-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull cpu hotplug fixes from Thomas Gleixner: "Two fixes for the cpu hotplug machinery: - Replace the overly clever 'SMT disabled by BIOS' detection logic as it breaks KVM scenarios and prevents speculation control updates when the Hyperthreads are brought online late after boot. - Remove a redundant invocation of the speculation control update function" * 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: cpu/hotplug: Fix "SMT disabled by BIOS" detection for KVM x86/speculation: Remove redundant arch_smt_update() invocation
2019-02-03Merge branch 'perf-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf fixes from Thomas Gleixner: "A pile of perf updates: - Fix broken sanity check in the /proc/sys/kernel/perf_cpu_time_max_percent write handler - Cure a perf script crash which caused by an unitinialized data structure - Highlight the hottest instruction in perf top and not a random one - Cure yet another clang issue when building perf python - Handle topology entries with no CPU correctly in the tools - Handle perf data which contains both tracepoints and performance counter entries correctly. - Add a missing NULL pointer check in perf ordered_events_free()" * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf script: Fix crash when processing recorded stat data perf top: Fix wrong hottest instruction highlighted perf tools: Handle TOPOLOGY headers with no CPU perf python: Remove -fstack-clash-protection when building with some clang versions perf core: Fix perf_proc_update_handler() bug perf script: Fix crash with printing mixed trace point and other events perf ordered_events: Fix crash in ordered_events__free
2019-02-01psi: fix aggregation idle shut-offJohannes Weiner
psi has provisions to shut off the periodic aggregation worker when there is a period of no task activity - and thus no data that needs aggregating. However, while developing psi monitoring, Suren noticed that the aggregation clock currently won't stay shut off for good. Debugging this revealed a flaw in the idle design: an aggregation run will see no task activity and decide to go to sleep; shortly thereafter, the kworker thread that executed the aggregation will go idle and cause a scheduling change, during which the psi callback will kick the !pending worker again. This will ping-pong forever, and is equivalent to having no shut-off logic at all (but with more code!) Fix this by exempting aggregation workers from psi's clock waking logic when the state change is them going to sleep. To do this, tag workers with the last work function they executed, and if in psi we see a worker going to sleep after aggregating psi data, we will not reschedule the aggregation work item. What if the worker is also executing other items before or after? Any psi state times that were incurred by work items preceding the aggregation work will have been collected from the per-cpu buckets during the aggregation itself. If there are work items following the aggregation work, the worker's last_func tag will be overwritten and the aggregator will be kept alive to process this genuine new activity. If the aggregation work is the last thing the worker does, and we decide to go idle, the brief period of non-idle time incurred between the aggregation run and the kworker's dequeue will be stranded in the per-cpu buckets until the clock is woken by later activity. But that should not be a problem. The buckets can hold 4s worth of time, and future activity will wake the clock with a 2s delay, giving us 2s worth of data we can leave behind when disabling aggregation. If it takes a worker more than two seconds to go idle after it finishes its last work item, we likely have bigger problems in the system, and won't notice one sample that was averaged with a bogus per-CPU weight. Link: http://lkml.kernel.org/r/20190116193501.1910-1-hannes@cmpxchg.org Fixes: eb414681d5a0 ("psi: pressure stall information for CPU, memory, and IO") Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Suren Baghdasaryan <surenb@google.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-02-01kernel/exit.c: release ptraced tasks before zap_pid_ns_processesAndrei Vagin
Currently, exit_ptrace() adds all ptraced tasks in a dead list, then zap_pid_ns_processes() waits on all tasks in a current pidns, and only then are tasks from the dead list released. zap_pid_ns_processes() can get stuck on waiting tasks from the dead list. In this case, we will have one unkillable process with one or more dead children. Thanks to Oleg for the advice to release tasks in find_child_reaper(). Link: http://lkml.kernel.org/r/20190110175200.12442-1-avagin@gmail.com Fixes: 7c8bd2322c7f ("exit: ptrace: shift "reap dead" code from exit_ptrace() to forget_original_parent()") Signed-off-by: Andrei Vagin <avagin@gmail.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-01-30cpu/hotplug: Fix "SMT disabled by BIOS" detection for KVMJosh Poimboeuf
With the following commit: 73d5e2b47264 ("cpu/hotplug: detect SMT disabled by BIOS") ... the hotplug code attempted to detect when SMT was disabled by BIOS, in which case it reported SMT as permanently disabled. However, that code broke a virt hotplug scenario, where the guest is booted with only primary CPU threads, and a sibling is brought online later. The problem is that there doesn't seem to be a way to reliably distinguish between the HW "SMT disabled by BIOS" case and the virt "sibling not yet brought online" case. So the above-mentioned commit was a bit misguided, as it permanently disabled SMT for both cases, preventing future virt sibling hotplugs. Going back and reviewing the original problems which were attempted to be solved by that commit, when SMT was disabled in BIOS: 1) /sys/devices/system/cpu/smt/control showed "on" instead of "notsupported"; and 2) vmx_vm_init() was incorrectly showing the L1TF_MSG_SMT warning. I'd propose that we instead consider #1 above to not actually be a problem. Because, at least in the virt case, it's possible that SMT wasn't disabled by BIOS and a sibling thread could be brought online later. So it makes sense to just always default the smt control to "on" to allow for that possibility (assuming cpuid indicates that the CPU supports SMT). The real problem is #2, which has a simple fix: change vmx_vm_init() to query the actual current SMT state -- i.e., whether any siblings are currently online -- instead of looking at the SMT "control" sysfs value. So fix it by: a) reverting the original "fix" and its followup fix: 73d5e2b47264 ("cpu/hotplug: detect SMT disabled by BIOS") bc2d8d262cba ("cpu/hotplug: Fix SMT supported evaluation") and b) changing vmx_vm_init() to query the actual current SMT state -- instead of the sysfs control value -- to determine whether the L1TF warning is needed. This also requires the 'sched_smt_present' variable to exported, instead of 'cpu_smt_control'. Fixes: 73d5e2b47264 ("cpu/hotplug: detect SMT disabled by BIOS") Reported-by: Igor Mammedov <imammedo@redhat.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Joe Mario <jmario@redhat.com> Cc: Jiri Kosina <jikos@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: kvm@vger.kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/e3a85d585da28cc333ecbc1e78ee9216e6da9396.1548794349.git.jpoimboe@redhat.com
2019-01-29x86/speculation: Remove redundant arch_smt_update() invocationZhenzhong Duan
With commit a74cfffb03b7 ("x86/speculation: Rework SMT state change"), arch_smt_update() is invoked from each individual CPU hotplug function. Therefore the extra arch_smt_update() call in the sysfs SMT control is redundant. Fixes: a74cfffb03b7 ("x86/speculation: Rework SMT state change") Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: <konrad.wilk@oracle.com> Cc: <dwmw@amazon.co.uk> Cc: <bp@suse.de> Cc: <srinivas.eeda@oracle.com> Cc: <peterz@infradead.org> Cc: <hpa@zytor.com> Link: https://lkml.kernel.org/r/e2e064f2-e8ef-42ca-bf4f-76b612964752@default
2019-01-27Merge branch 'timers-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timer fix from Thomas Glexiner: "A single regression fix to address the unintended breakage of posix cpu timers. This is caused by a new sanity check in the common code, which fails for posix cpu timers under certain conditions because the posix cpu timer code never updates the variable which is checked" * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: posix-cpu-timers: Unbreak timer rearming
2019-01-27Merge branch 'locking-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking fixes from Thomas Gleixner: "A small series of fixes which all address possible missed wakeups: - Document and fix the wakeup ordering of wake_q - Add the missing barrier in rcuwait_wake_up(), which was documented in the comment but missing in the code - Fix the possible missed wakeups in the rwsem and futex code" * 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/rwsem: Fix (possible) missed wakeup futex: Fix (possible) missed wakeup sched/wake_q: Fix wakeup ordering for wake_q sched/wake_q: Document wake_q_add() sched/wait: Fix rcuwait_wake_up() ordering
2019-01-27Merge branch 'irq-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull irq fixes from Thomas Gleixner: "A small set of fixes for the interrupt subsystem: - Fix a double increment in the irq descriptor allocator which resulted in a sanity check only being done for every second affinity mask - Add a missing device tree translation in the stm32-exti driver. Without that the interrupt association is completely wrong. - Initialize the mutex in the GIC-V3 MBI driver - Fix the alignment for aliasing devices in the GIC-V3-ITS driver so multi MSI allocations work correctly - Ensure that the initial affinity of a interrupt is not empty at startup time. - Drop bogus include in the madera irq chip driver - Fix KernelDoc regression" * 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: irqchip/gic-v3-its: Align PCI Multi-MSI allocation on their size genirq/irqdesc: Fix double increment in alloc_descs() genirq: Fix the kerneldoc comment for struct irq_affinity_desc irqchip/madera: Drop GPIO includes irqchip/gic-v3-mbi: Fix uninitialized mbi_lock irqchip/stm32-exti: Add domain translate function genirq: Make sure the initial affinity is not empty
2019-01-22Merge tag 'perf-urgent-for-mingo-5.0-20190121' of ↵Ingo Molnar
git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/urgent Pull perf/urgent fixes from Arnaldo Carvalho de Melo: Kernel: Stephane Eranian: - Fix perf_proc_update_handler() bug. perf script: Andi Kleen: - Fix crash with printing mixed trace point and other events. Tony Jones: - Fix crash when processing recorded stat data. perf top: He Kuang: - Fix wrong hottest instruction highlighted. perf python: Arnaldo Carvalho de Melo: - Remove -fstack-clash-protection when building with some clang versions. perf ordered_events: Jiri Olsa: - Fix out of buffers crash in ordered_events__free(). perf cpu_map: Stephane Eranian: - Handle TOPOLOGY headers with no CPU. Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-01-21locking/rwsem: Fix (possible) missed wakeupXie Yongji
Because wake_q_add() can imply an immediate wakeup (cmpxchg failure case), we must not rely on the wakeup being delayed. However, commit: e38513905eea ("locking/rwsem: Rework zeroing reader waiter->task") relies on exactly that behaviour in that the wakeup must not happen until after we clear waiter->task. [ peterz: Added changelog. ] Signed-off-by: Xie Yongji <xieyongji@baidu.com> Signed-off-by: Zhang Yu <zhangyu31@baidu.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: e38513905eea ("locking/rwsem: Rework zeroing reader waiter->task") Link: https://lkml.kernel.org/r/1543495830-2644-1-git-send-email-xieyongji@baidu.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-01-21futex: Fix (possible) missed wakeupPeter Zijlstra
We must not rely on wake_q_add() to delay the wakeup; in particular commit: 1d0dcb3ad9d3 ("futex: Implement lockless wakeups") moved wake_q_add() before smp_store_release(&q->lock_ptr, NULL), which could result in futex_wait() waking before observing ->lock_ptr == NULL and going back to sleep again. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 1d0dcb3ad9d3 ("futex: Implement lockless wakeups") Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-01-21sched/wake_q: Fix wakeup ordering for wake_qPeter Zijlstra
Notable cmpxchg() does not provide ordering when it fails, however wake_q_add() requires ordering in this specific case too. Without this it would be possible for the concurrent wakeup to not observe our prior state. Andrea Parri provided: C wake_up_q-wake_q_add { int next = 0; int y = 0; } P0(int *next, int *y) { int r0; /* in wake_up_q() */ WRITE_ONCE(*next, 1); /* node->next = NULL */ smp_mb(); /* implied by wake_up_process() */ r0 = READ_ONCE(*y); } P1(int *next, int *y) { int r1; /* in wake_q_add() */ WRITE_ONCE(*y, 1); /* wake_cond = true */ smp_mb__before_atomic(); r1 = cmpxchg_relaxed(next, 1, 2); } exists (0:r0=0 /\ 1:r1=0) This "exists" clause cannot be satisfied according to the LKMM: Test wake_up_q-wake_q_add Allowed States 3 0:r0=0; 1:r1=1; 0:r0=1; 1:r1=0; 0:r0=1; 1:r1=1; No Witnesses Positive: 0 Negative: 3 Condition exists (0:r0=0 /\ 1:r1=0) Observation wake_up_q-wake_q_add Never 0 3 Reported-by: Yongji Xie <elohimes@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-01-21sched/wake_q: Document wake_q_add()Peter Zijlstra
The only guarantee provided by wake_q_add() is that a wakeup will happen after it, it does _NOT_ guarantee the wakeup will be delayed until the matching wake_up_q(). If wake_q_add() fails the cmpxchg() a concurrent wakeup is pending and that can happen at any time after the cmpxchg(). This means we should not rely on the wakeup happening at wake_q_up(), but should be ready for wake_q_add() to issue the wakeup. The delay; if provided (most likely); should only result in more efficient behaviour. Reported-by: Yongji Xie <elohimes@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Waiman Long <longman@redhat.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-01-21sched/wait: Fix rcuwait_wake_up() orderingPrateek Sood
For some peculiar reason rcuwait_wake_up() has the right barrier in the comment, but not in the code. This mistake has been observed to cause a deadlock in the following situation: P1 P2 percpu_up_read() percpu_down_write() rcu_sync_is_idle() // false rcu_sync_enter() ... __percpu_up_read() [S] ,- __this_cpu_dec(*sem->read_count) | smp_rmb(); [L] | task = rcu_dereference(w->task) // NULL | | [S] w->task = current | smp_mb(); | [L] readers_active_check() // fail `-> <store happens here> Where the smp_rmb() (obviously) fails to constrain the store. [ peterz: Added changelog. ] Signed-off-by: Prateek Sood <prsood@codeaurora.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Andrea Parri <andrea.parri@amarulasolutions.com> Acked-by: Davidlohr Bueso <dbueso@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 8f95c90ceb54 ("sched/wait, RCU: Introduce rcuwait machinery") Link: https://lkml.kernel.org/r/1543590656-7157-1-git-send-email-prsood@codeaurora.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-01-21Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netLinus Torvalds
Pull networking fixes from David Miller: 1) Fix endless loop in nf_tables, from Phil Sutter. 2) Fix cross namespace ip6_gre tunnel hash list corruption, from Olivier Matz. 3) Don't be too strict in phy_start_aneg() otherwise we might not allow restarting auto negotiation. From Heiner Kallweit. 4) Fix various KMSAN uninitialized value cases in tipc, from Ying Xue. 5) Memory leak in act_tunnel_key, from Davide Caratti. 6) Handle chip errata of mv88e6390 PHY, from Andrew Lunn. 7) Remove linear SKB assumption in fou/fou6, from Eric Dumazet. 8) Missing udplite rehash callbacks, from Alexey Kodanev. 9) Log dirty pages properly in vhost, from Jason Wang. 10) Use consume_skb() in neigh_probe() as this is a normal free not a drop, from Yang Wei. Likewise in macvlan_process_broadcast(). 11) Missing device_del() in mdiobus_register() error paths, from Thomas Petazzoni. 12) Fix checksum handling of short packets in mlx5, from Cong Wang. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (96 commits) bpf: in __bpf_redirect_no_mac pull mac only if present virtio_net: bulk free tx skbs net: phy: phy driver features are mandatory isdn: avm: Fix string plus integer warning from Clang net/mlx5e: Fix cb_ident duplicate in indirect block register net/mlx5e: Fix wrong (zero) TX drop counter indication for representor net/mlx5e: Fix wrong error code return on FEC query failure net/mlx5e: Force CHECKSUM_UNNECESSARY for short ethernet frames tools: bpftool: Cleanup license mess bpf: fix inner map masking to prevent oob under speculation bpf: pull in pkt_sched.h header for tooling to fix bpftool build selftests: forwarding: Add a test case for externally learned FDB entries selftests: mlxsw: Test FDB offload indication mlxsw: spectrum_switchdev: Do not treat static FDB entries as sticky net: bridge: Mark FDB entries that were added by user as such mlxsw: spectrum_fid: Update dummy FID index mlxsw: pci: Return error on PCI reset timeout mlxsw: pci: Increase PCI SW reset timeout mlxsw: pci: Ring CQ's doorbell before RDQ's MAINTAINERS: update email addresses of liquidio driver maintainers ...
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