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2017-04-20tracing/ftrace: Allow instances to have their own function probesSteven Rostedt (VMware)
Pass around the local trace_array that is the descriptor for tracing instances, when enabling and disabling probes. This by default sets the enable/disable of event probe triggers to work with instances. The other probes will need some more work to get them working with instances. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20tracing/ftrace: Add a better way to pass data via the probe functionsSteven Rostedt (VMware)
With the redesign of the registration and execution of the function probes (triggers), data can now be passed from the setup of the probe to the probe callers that are specific to the trace_array it is on. Although, all probes still only affect the toplevel trace array, this change will allow for instances to have their own probes separated from other instances and the top array. That is, something like the stacktrace probe can be set to trace only in an instance and not the toplevel trace array. This isn't implement yet, but this change sets the ground work for the change. When a probe callback is triggered (someone writes the probe format into set_ftrace_filter), it calls register_ftrace_function_probe() passing in init_data that will be used to initialize the probe. Then for every matching function, register_ftrace_function_probe() will call the probe_ops->init() function with the init data that was passed to it, as well as an address to a place holder that is associated with the probe and the instance. The first occurrence will have a NULL in the pointer. The init() function will then initialize it. If other probes are added, or more functions are part of the probe, the place holder will be passed to the init() function with the place holder data that it was initialized to the last time. Then this place_holder is passed to each of the other probe_ops functions, where it can be used in the function callback. When the probe_ops free() function is called, it can be called either with the rip of the function that is being removed from the probe, or zero, indicating that there are no more functions attached to the probe, and the place holder is about to be freed. This gives the probe_ops a way to free the data it assigned to the place holder if it was allocade during the first init call. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20ftrace: Dynamically create the probe ftrace_ops for the trace_arraySteven Rostedt (VMware)
In order to eventually have each trace_array instance have its own unique set of function probes (triggers), the trace array needs to hold the ops and the filters for the probes. This is the first step to accomplish this. Instead of having the private data of the probe ops point to the trace_array, create a separate list that the trace_array holds. There's only one private_data for a probe, we need one per trace_array. The probe ftrace_ops will be dynamically created for each instance, instead of being static. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20tracing: Pass the trace_array into ftrace_probe_ops functionsSteven Rostedt (VMware)
Pass the trace_array associated to a ftrace_probe_ops into the probe_ops func(), init() and free() functions. The trace_array is the descriptor that describes a tracing instance. This will help create the infrastructure that will allow having function probes unique to tracing instances. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20tracing: Have the trace_array hold the list of registered func probesSteven Rostedt (VMware)
Add a link list to the trace_array to hold func probes that are registered. Currently, all function probes are the same for all instances as it was before, that is, only the top level trace_array holds the function probes. But this lays the ground work to have function probes be attached to individual instances, and having the event trigger only affect events in the given instance. But that work is still to be done. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20ftrace: If the hash for a probe fails to update then free what was initializedSteven Rostedt (VMware)
If the ftrace_hash_move_and_update_ops() fails, and an ops->free() function exists, then it needs to be called on all the ops that were added by this registration. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20ftrace: Have the function probes call their own functionSteven Rostedt (VMware)
Now that the function probes have their own ftrace_ops, there's no reason to continue using the ftrace_func_hash to find which probe to call in the function callback. The ops that is passed in to the function callback is part of the probe_ops to call. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20ftrace: Have each function probe use its own ftrace_opsSteven Rostedt (VMware)
Have the function probes have their own ftrace_ops, and remove the trace_probe_ops. This simplifies some of the ftrace infrastructure code. Individual entries for each function is still allocated for the use of the output for set_ftrace_filter, but they will be removed soon too. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20ftrace: Have unregister_ftrace_function_probe_func() return a valueSteven Rostedt (VMware)
Currently unregister_ftrace_function_probe_func() is a void function. It does not give any feedback if an error occurred or no item was found to remove and nothing was done. Change it to return status and success if it removed something. Also update the callers to return that feedback to the user. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20ftrace: Add helper function ftrace_hash_move_and_update_ops()Steven Rostedt (VMware)
The processes of updating a ops filter_hash is a bit complex, and requires setting up an old hash to perform the update. This is done exactly the same in two locations for the same reasons. Create a helper function that does it in one place. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20ftrace: Remove data field from ftrace_func_probe structureSteven Rostedt (VMware)
No users of the function probes uses the data field anymore. Remove it, and change the init function to take a void *data parameter instead of a void **data, because the init will just get the data that the registering function was received, and there's no state after it is called. The other functions for ftrace_probe_ops still take the data parameter, but it will currently only be passed NULL. It will stay as a parameter for future data to be passed to these functions. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20ftrace: Remove printing of data in showing of a function probeSteven Rostedt (VMware)
None of the probe users uses the data field anymore of the entry. They all have their own print() function. Remove showing the data field in the generic function as the data field will be going away. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20ftrace: Remove unused unregister_ftrace_function_probe_all() functionSteven Rostedt (VMware)
There are no users of unregister_ftrace_function_probe_all(). The only probe function that is used is unregister_ftrace_function_probe_func(). Rename the internal static function __unregister_ftrace_function_probe() to unregister_ftrace_function_probe_func() and make it global. Also remove the PROBE_TEST_FUNC as it would be always set. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20ftrace: Remove unused unregister_ftrace_function_probe() functionSteven Rostedt (VMware)
Nothing calls unregister_ftrace_function_probe(). Remove it as well as the flag PROBE_TEST_DATA, as this function was the only one to set it. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20ftrace: Convert the rest of the function trigger over to the mapping functionsSteven Rostedt (VMware)
As the data pointer for individual ips will soon be removed and no longer passed to the callback function probe handlers, convert the rest of the function trigger counters over to the new ftrace_func_mapper helper functions. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20tracing: Have the snapshot trigger use the mapping helper functionsSteven Rostedt (VMware)
As the data pointer for individual ips will soon be removed and no longer passed to the callback function probe handlers, convert the snapshot trigger counter over to the new ftrace_func_mapper helper functions. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20ftrace: Added ftrace_func_mapper for function probe triggersSteven Rostedt (VMware)
In order to move the ops to the function probes directly, they need a way to map function ips to their own data without depending on the infrastructure of the function probes, as the data field will be going away. New helper functions are added that are based on the ftrace_hash code. ftrace_func_mapper functions are there to let the probes map ips to their data. These can be allocated by the probe ops, and referenced in the function callbacks. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20ftrace: Pass probe ops to probe functionSteven Rostedt (VMware)
In preparation to cleaning up the probe function registration code, the "data" parameter will eventually be removed from the probe->func() call. Instead it will receive its own "ops" function, in which it can set up its own data that it needs to map. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20ftrace: Remove unused "flags" field from struct ftrace_func_probeSteven Rostedt (VMware)
Nothing uses "flags" in the ftrace_func_probe descriptor. Remove it. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20ftrace: Move the function commands into the tracing directorySteven Rostedt (VMware)
As nothing outside the tracing directory uses the function command mechanism, I'm moving the prototypes out of the include/linux/ftrace.h and into the local kernel/trace/trace.h header. I plan on making them hook to the trace_array structure which is local to kernel/trace, and I do not want to expose it to the rest of the kernel. This requires that the command functions must also be local to tracing. But luckily nothing else uses them. Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-20Merge tag 'trace-v4.11-rc5-5' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull two more ftrace fixes from Steven Rostedt: "While continuing my development, I uncovered two more small bugs. One is a race condition when enabling the snapshot function probe trigger. It enables the probe before allocating the snapshot, and if the probe triggers first, it stops tracing with a warning that the snapshot buffer was not allocated. The seconds is that the snapshot file should show how to use it when it is empty. But a bug fix from long ago broke the "is empty" test and the snapshot file no longer displays the help message" * tag 'trace-v4.11-rc5-5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: ring-buffer: Have ring_buffer_iter_empty() return true when empty tracing: Allocate the snapshot buffer before enabling probe
2017-04-20block: remove the errors field from struct requestChristoph Hellwig
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com> Acked-by: Roger Pau Monné <roger.pau@citrix.com> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-20blktrace: remove the unused block_rq_abort tracepointChristoph Hellwig
Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-04-20Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller
A function in kernel/bpf/syscall.c which got a bug fix in 'net' was moved to kernel/bpf/verifier.c in 'net-next'. Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-20Merge branch 'linus' into irq/coreThomas Gleixner
Pick up upstream fixes to avoid conflicts with pending patches.
2017-04-20genirq/affinity: Fix calculating vectors to assignKeith Busch
The vectors_per_node is calculated from the remaining available vectors. The current vector starts after pre_vectors, so we need to subtract that from the current to properly account for the number of remaining vectors to assign. Fixes: 3412386b531 ("irq/affinity: Fix extra vecs calculation") Reported-by: Andrei Vagin <avagin@virtuozzo.com> Signed-off-by: Keith Busch <keith.busch@intel.com> Link: http://lkml.kernel.org/r/1492645870-13019-1-git-send-email-keith.busch@intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-04-20powerpc/kprobes: Fix handling of function offsets on ABIv2Naveen N. Rao
commit 239aeba76409 ("perf powerpc: Fix kprobe and kretprobe handling with kallsyms on ppc64le") changed how we use the offset field in struct kprobe on ABIv2. perf now offsets from the global entry point if an offset is specified and otherwise chooses the local entry point. Fix the same in kernel for kprobe API users. We do this by extending kprobe_lookup_name() to accept an additional parameter to indicate the offset specified with the kprobe registration. If offset is 0, we return the local function entry and return the global entry point otherwise. With: # cd /sys/kernel/debug/tracing/ # echo "p _do_fork" >> kprobe_events # echo "p _do_fork+0x10" >> kprobe_events before this patch: # cat ../kprobes/list c0000000000d0748 k _do_fork+0x8 [DISABLED] c0000000000d0758 k _do_fork+0x18 [DISABLED] c0000000000412b0 k kretprobe_trampoline+0x0 [OPTIMIZED] and after: # cat ../kprobes/list c0000000000d04c8 k _do_fork+0x8 [DISABLED] c0000000000d04d0 k _do_fork+0x10 [DISABLED] c0000000000412b0 k kretprobe_trampoline+0x0 [OPTIMIZED] Acked-by: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2017-04-20kprobes: Convert kprobe_lookup_name() to a functionNaveen N. Rao
The macro is now pretty long and ugly on powerpc. In the light of further changes needed here, convert it to a __weak variant to be over-ridden with a nicer looking function. Suggested-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2017-04-20kprobes: Skip preparing optprobe if the probe is ftrace-basedMasami Hiramatsu
Skip preparing optprobe if the probe is ftrace-based, since anyway, it must not be optimized (or already optimized by ftrace). Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2017-04-20timer/sysclt: Restrict timer migration sysctl values to 0 and 1Myungho Jung
timer_migration sysctl acts as a boolean switch, so the allowed values should be restricted to 0 and 1. Add the necessary extra fields to the sysctl table entry to enforce that. [ tglx: Rewrote changelog ] Signed-off-by: Myungho Jung <mhjungk@gmail.com> Link: http://lkml.kernel.org/r/1492640690-3550-1-git-send-email-mhjungk@gmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-04-19ring-buffer: Have ring_buffer_iter_empty() return true when emptySteven Rostedt (VMware)
I noticed that reading the snapshot file when it is empty no longer gives a status. It suppose to show the status of the snapshot buffer as well as how to allocate and use it. For example: ># cat snapshot # tracer: nop # # # * Snapshot is allocated * # # Snapshot commands: # echo 0 > snapshot : Clears and frees snapshot buffer # echo 1 > snapshot : Allocates snapshot buffer, if not already allocated. # Takes a snapshot of the main buffer. # echo 2 > snapshot : Clears snapshot buffer (but does not allocate or free) # (Doesn't have to be '2' works with any number that # is not a '0' or '1') But instead it just showed an empty buffer: ># cat snapshot # tracer: nop # # entries-in-buffer/entries-written: 0/0 #P:4 # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / delay # TASK-PID CPU# |||| TIMESTAMP FUNCTION # | | | |||| | | What happened was that it was using the ring_buffer_iter_empty() function to see if it was empty, and if it was, it showed the status. But that function was returning false when it was empty. The reason was that the iter header page was on the reader page, and the reader page was empty, but so was the buffer itself. The check only tested to see if the iter was on the commit page, but the commit page was no longer pointing to the reader page, but as all pages were empty, the buffer is also. Cc: stable@vger.kernel.org Fixes: 651e22f2701b ("ring-buffer: Always reset iterator to reader page") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-19tracing: Allocate the snapshot buffer before enabling probeSteven Rostedt (VMware)
Currently the snapshot trigger enables the probe and then allocates the snapshot. If the probe triggers before the allocation, it could cause the snapshot to fail and turn tracing off. It's best to allocate the snapshot buffer first, and then enable the trigger. If something goes wrong in the enabling of the trigger, the snapshot buffer is still allocated, but it can also be freed by the user by writting zero into the snapshot buffer file. Also add a check of the return status of alloc_snapshot(). Cc: stable@vger.kernel.org Fixes: 77fd5c15e3 ("tracing: Add snapshot trigger to function probes") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-04-19rcu: Fix typo in PER_RCU_NODE_PERIOD header commentPaul E. McKenney
This commit just changes a "the the" to "the" to reduce repetition. Reported-by: Michalis Kokologiannakis <mixaskok@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-19rcu: Use true/false in assignment to boolNicholas Mc Guire
This commit makes the parse_rcu_nocb_poll() function assign true (rather than the constant 1) to the bool variable rcu_nocb_poll. Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-19rcu: Use bool value directlyNicholas Mc Guire
The beenonline variable is declared bool so there is no need for an explicit comparison, especially not against the constant zero. Signed-off-by: Nicholas Mc Guire <der.herr@hofr.at> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-19rcu: Improve comments for hotplug/suspend/hibernate functionsPaul E. McKenney
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-19rcu: Remove obsolete comment from rcu_future_gp_cleanup() headerPaul E. McKenney
The rcu_nocb_gp_cleanup() function is now invoked elsewhere, so this commit drags this comment into the year 2017. Reported-by: Michalis Kokologiannakis <mixaskok@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-19lockdep: Use "WARNING" tag on lockdep splatsPaul E. McKenney
This commit changes lockdep splats to begin lines with "WARNING" and to use pr_warn() instead of printk(). This change eases scripted analysis of kernel console output. Reported-by: Dmitry Vyukov <dvyukov@google.com> Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Dmitry Vyukov <dvyukov@google.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2017-04-19Merge tag 'v4.11-rc7' into drm-nextDave Airlie
Backmerge Linux 4.11-rc7 from Linus tree, to fix some conflicts that were causing problems with the rerere cache in drm-tip.
2017-04-18Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparcLinus Torvalds
Pull sparc fixes from David Miller: "Two Sparc bug fixes from Daniel Jordan and Nitin Gupta" * git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc: sparc64: Fix hugepage page table free sparc64: Use LOCKDEP_SMALL, not PROVE_LOCKING_SMALL
2017-04-18Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netLinus Torvalds
Pull networking fixes from David Miller: 1) BPF tail call handling bug fixes from Daniel Borkmann. 2) Fix allowance of too many rx queues in sfc driver, from Bert Kenward. 3) Non-loopback ipv6 packets claiming src of ::1 should be dropped, from Florian Westphal. 4) Statistics requests on KSZ9031 can crash, fix from Grygorii Strashko. 5) TX ring handling fixes in mediatek driver, from Sean Wang. 6) ip_ra_control can deadlock, fix lock acquisition ordering to fix, from Cong WANG. 7) Fix use after free in ip_recv_error(), from Willem de Buijn. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: bpf: fix checking xdp_adjust_head on tail calls bpf: fix cb access in socket filter programs on tail calls ipv6: drop non loopback packets claiming to originate from ::1 net: ethernet: mediatek: fix inconsistency of port number carried in TXD net: ethernet: mediatek: fix inconsistency between TXD and the used buffer net: phy: micrel: fix crash when statistic requested for KSZ9031 phy net: vrf: Fix setting NLM_F_EXCL flag when adding l3mdev rule net: thunderx: Fix set_max_bgx_per_node for 81xx rgx net-timestamp: avoid use-after-free in ip_recv_error ipv4: fix a deadlock in ip_ra_control sfc: limit the number of receive queues
2017-04-18sparc64: Use LOCKDEP_SMALL, not PROVE_LOCKING_SMALLDaniel Jordan
CONFIG_PROVE_LOCKING_SMALL shrinks the memory usage of lockdep so the kernel text, data, and bss fit in the required 32MB limit, but this option is not set for every config that enables lockdep. A 4.10 kernel fails to boot with the console output Kernel: Using 8 locked TLB entries for main kernel image. hypervisor_tlb_lock[2000000:0:8000000071c007c3:1]: errors with f Program terminated with these config options CONFIG_LOCKDEP=y CONFIG_LOCK_STAT=y CONFIG_PROVE_LOCKING=n To fix, rename CONFIG_PROVE_LOCKING_SMALL to CONFIG_LOCKDEP_SMALL, and enable this option with CONFIG_LOCKDEP=y so we get the reduced memory usage every time lockdep is turned on. Tested that CONFIG_LOCKDEP_SMALL is set to 'y' if and only if CONFIG_LOCKDEP is set to 'y'. When other lockdep-related config options that select CONFIG_LOCKDEP are enabled (e.g. CONFIG_LOCK_STAT or CONFIG_PROVE_LOCKING), verified that CONFIG_LOCKDEP_SMALL is also enabled. Fixes: e6b5f1be7afe ("config: Adding the new config parameter CONFIG_PROVE_LOCKING_SMALL for sparc") Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com> Reviewed-by: Babu Moger <babu.moger@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-18mm: Rename SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCUPaul E. McKenney
A group of Linux kernel hackers reported chasing a bug that resulted from their assumption that SLAB_DESTROY_BY_RCU provided an existence guarantee, that is, that no block from such a slab would be reallocated during an RCU read-side critical section. Of course, that is not the case. Instead, SLAB_DESTROY_BY_RCU only prevents freeing of an entire slab of blocks. However, there is a phrase for this, namely "type safety". This commit therefore renames SLAB_DESTROY_BY_RCU to SLAB_TYPESAFE_BY_RCU in order to avoid future instances of this sort of confusion. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: <linux-mm@kvack.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> [ paulmck: Add comments mentioning the old name, as requested by Eric Dumazet, in order to help people familiar with the old name find the new one. ] Acked-by: David Rientjes <rientjes@google.com>
2017-04-18genirq: Return the IRQ name from free_irq()Christoph Hellwig
This allows callers to get back at them instead of having to store it in another variable. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2017-04-18genirq: Fix indentation in remove_irq()Christoph Hellwig
Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
2017-04-18srcu: Introduce CLASSIC_SRCU Kconfig optionPaul E. McKenney
The TREE_SRCU rewrite is large and a bit on the non-simple side, so this commit helps reduce risk by allowing the old v4.11 SRCU algorithm to be selected using a new CLASSIC_SRCU Kconfig option that depends on RCU_EXPERT. The default is to use the new TREE_SRCU and TINY_SRCU algorithms, in order to help get these the testing that they need. However, if your users do not require the update-side scalability that is to be provided by TREE_SRCU, select RCU_EXPERT and then CLASSIC_SRCU to revert back to the old classic SRCU algorithm. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-18srcutorture: Print Tiny SRCU reader statisticsPaul E. McKenney
The srcu_torture_stats() function is adapted to the specific srcu_struct layout traditionally used by SRCU. This commit therefore adds support for Tiny SRCU. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-18srcu: Create a tiny SRCUPaul E. McKenney
In response to automated complaints about modifications to SRCU increasing its size, this commit creates a tiny SRCU that is used in SMP=n && PREEMPT=n builds. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-18srcu: Crude control of expedited grace periodsPaul E. McKenney
SRCU's implementation of expedited grace periods has always assumed that the SRCU instance is idle when the expedited request arrives. This commit improves this a bit by maintaining a count of the number of outstanding expedited requests, thus allowing prior non-expedited grace periods accommodate these requests by shifting to expedited mode. However, any non-expedited wait already in progress will still wait for the full duration. Improved control of expedited grace periods is planned, but one step at a time. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-18srcu: Merge ->srcu_state into ->srcu_gp_seqPaul E. McKenney
Updating ->srcu_state and ->srcu_gp_seq will lead to extremely complex race conditions given multiple callback queues, so this commit takes advantage of the two-bit state now available in rcu_seq counters to store the state in the bottom two bits of ->srcu_gp_seq. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>