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copy_siginfo_from_user_any() takes a userspace pointer as second
argument; annotate the parameter type accordingly.
Signed-off-by: Jann Horn <jannh@google.com>
Link: https://lore.kernel.org/r/20201207000252.138564-1-jannh@google.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging
Pull staging driver fixes from Greg KH:
"Here are some small staging driver fixes for 5.11-rc3. Nothing major,
just resolving some reported issues:
- cleanup some remaining mentions of the ION drivers that were
removed in 5.11-rc1
- comedi driver bugfix
- two error path memory leak fixes
All have been in linux-next for a while with no reported issues"
* tag 'staging-5.11-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
staging: ION: remove some references to CONFIG_ION
staging: mt7621-dma: Fix a resource leak in an error handling path
Staging: comedi: Return -EFAULT if copy_to_user() fails
staging: spmi: hisi-spmi-controller: Fix some error handling paths
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Move function tracer options to Kconfig to make it easier to add
new methods for generating __mcount_loc, and to make the options
available also when building kernel modules.
Note that FTRACE_MCOUNT_USE_* options are updated on rebuild and
therefore, work even if the .config was generated in a different
environment.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201211184633.3213045-2-samitolvanen@google.com
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This program does not use argp (which is a glibcism). Instead include <errno.h>
directly, which was pulled in by <argp.h>.
Signed-off-by: Leah Neukirchen <leah@vuxu.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20201216100306.30942-1-leah@vuxu.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Song reported a boot regression in a kvm image with 5.11-rc, and bisected
it down to the below patch. Debugging this issue, turns out that the boot
stalled when a task is waiting on a pipe being released. As we no longer
run task_work from get_signal() unless it's queued with TWA_SIGNAL, the
task goes idle without running the task_work. This prevents ->release()
from being called on the pipe, which another boot task is waiting on.
For now, re-instate the unconditional task_work run from get_signal().
For 5.12, we'll collapse TWA_RESUME and TWA_SIGNAL, as it no longer
makes sense to have a distinction between the two. This will turn
task_work notification into a simple boolean, whether to notify or not.
Fixes: 98b89b649fce ("signal: kill JOBCTL_TASK_WORK")
Reported-by: Song Liu <songliubraving@fb.com>
Tested-by: John Stultz <john.stultz@linaro.org>
Tested-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang version 11.0.1
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Alexei Starovoitov says:
====================
pull-request: bpf 2021-01-07
We've added 4 non-merge commits during the last 10 day(s) which contain
a total of 4 files changed, 14 insertions(+), 7 deletions(-).
The main changes are:
1) Fix task_iter bug caused by the merge conflict resolution, from Yonghong.
2) Fix resolve_btfids for multiple type hierarchies, from Jiri.
* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
bpftool: Fix compilation failure for net.o with older glibc
tools/resolve_btfids: Warn when having multiple IDs for single type
bpf: Fix a task_iter bug caused by a merge conflict resolution
selftests/bpf: Fix a compile error for BPF_F_BPRM_SECUREEXEC
====================
Link: https://lore.kernel.org/r/20210107221555.64959-1-alexei.starovoitov@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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The TREE01 rcutorture scenario intentionally creates confusion as to the
number of available CPUs by specifying the "maxcpus=8 nr_cpus=43" kernel
boot parameters. This can disable rcutorture's load shedding, which
currently uses num_online_cpus(), which would count the extra 35 CPUs.
However, the rcutorture guest OS will be provisioned with only 8 CPUs,
which means that rcutorture will present full load even when all but one
of the original 8 CPUs are offline. This can result in spurious errors
due to extreme overloading of that single remaining CPU.
This commit therefore keeps a separate set of books on the number of
usable online CPUs, so that torture_num_online_cpus() is used for load
shedding instead of num_online_cpus(). Note that initial sizing must
use num_online_cpus() because torture_num_online_cpus() will return
NR_CPUS until shortly after torture_onoff_init() is invoked.
Reported-by: Frederic Weisbecker <frederic@kernel.org>
[ paulmck: Apply feedback from kernel test robot. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit puts all CPUs back online at the end of a torture test,
and also unconditionally puts them online at the beginning of the test,
rather than just in the case of built-in tests. This allows torture tests
to behave in a predictable manner, whether built-in or based on modules.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit provides a test for call_rcu() printing the allocation address
of a double-freed callback by double-freeing a callback allocated via
kmalloc(). However, this commit does not depend on any other commit.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds kernel boot parameters torture.verbose_sleep_frequency
and torture.verbose_sleep_duration, which allow VERBOSE_TOROUT_*() output
to be throttled with periodic sleeps on large systems.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds a short delay for verbose_batched-throttled printk()s
to further decrease console flooding.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit replaces schedule_timeout_uninterruptible() and
schedule_timeout_interruptible() with torture_hrtimeout_us() and
torture_hrtimeout_jiffies() to avoid timer-wheel synchronization.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit saves a few lines of code by making the stutter_wait()
and torture_stutter() functions use torture_hrtimeout_jiffies() and
torture_hrtimeout_us().
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Because rcu_torture_writer() and rcu_torture_fakewriter() predate
hrtimers, they do timer-wheel-decoupled timed waits by using the
timer-wheel-based schedule_timeout_interruptible() functions in
conjunction with a random udelay()-based wait. This latter unnecessarily
burns CPU time, so this commit instead uses torture_hrtimeout_jiffies()
to decouple from the timer wheels without busy-waiting.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds torture_hrtimeout_ns(), torture_hrtimeout_us(),
torture_hrtimeout_ms(), torture_hrtimeout_jiffies(), and
torture_hrtimeout_s(), each of which uses hrtimers to block for a fuzzed
time interval. These functions are intended to be used by the various
torture tests to decouple wakeups from the timer wheel, thus providing
more opportunity for Murphy to insert destructive race conditions.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Full testing of the new SRCU polling API requires that the fake
writers also use it in order to test concurrent calls to all of the API
members, especially start_poll_synchronize_srcu(). This commit makes
rcu_torture_fakewriter() use all available blocking grace-period-wait
primitives available from the RCU flavor under test.
Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Full testing of the new SRCU polling API requires that the fake writers
also use it in order to test concurrent calls to all of the API members,
especially start_poll_synchronize_srcu(). This commit prepares the ground
for this by making the synctype[] and nsynctype variables be static
globals so that the rcu_torture_fakewriter() function can access them.
Initialization of these variables is moved from rcu_torture_writer()
to a new rcu_torture_write_types() function that is invoked from
rcu_torture_init() just before the first writer kthread is spawned.
Link: https://lore.kernel.org/rcu/20201112201547.GF3365678@moria.home.lan/
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Currently, the rcu_torture_writer() function checks that all required
grace periods elapse during a stutter interval, which is a multi-second
time period during which the test load is removed. However, this check
is suppressed during early boot (that is, before init is spawned) in
order to avoid false positives that otherwise occur due to heavy load
on the single boot CPU.
Unfortunately, this approach is insufficient. It is possible that the
stutter interval might end just as init is spawned, so that early boot
conditions prevailed during almost the entire stutter interval.
This commit therefore takes a snapshot of boot-complete state just
before the stutter interval, thus suppressing the check for failure to
complete grace periods unless the entire stutter interval took place
after early boot.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The refscale test prints enough per-kthread console output to provoke RCU
CPU stall warnings on large systems. This commit therefore allows this
output to be summarized. For example, the refscale.verbose_batched=32
boot parameter would causes only every 32nd line of output to be logged.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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For a new grace period request, the RCU GP kthread transitions through
following states:
a. [RCU_GP_WAIT_GPS] -> [RCU_GP_DONE_GPS]
The RCU_GP_WAIT_GPS state is where the GP kthread waits for a request
for a new GP. Once it receives a request (for example, when a new RCU
callback is queued), the GP kthread transitions to RCU_GP_DONE_GPS.
b. [RCU_GP_DONE_GPS] -> [RCU_GP_ONOFF]
Grace period initialization starts in rcu_gp_init(), which records the
start of new GP in rcu_state.gp_seq and transitions to RCU_GP_ONOFF.
c. [RCU_GP_ONOFF] -> [RCU_GP_INIT]
The purpose of the RCU_GP_ONOFF state is to apply the online/offline
information that was buffered for any CPUs that recently came online or
went offline. This state is maintained in per-leaf rcu_node bitmasks,
with the buffered state in ->qsmaskinitnext and the state for the upcoming
GP in ->qsmaskinit. At the end of this RCU_GP_ONOFF state, each bit in
->qsmaskinit will correspond to a CPU that must pass through a quiescent
state before the upcoming grace period is allowed to complete.
However, a leaf rcu_node structure with an all-zeroes ->qsmaskinit
cannot necessarily be ignored. In preemptible RCU, there might well be
tasks still in RCU read-side critical sections that were first preempted
while running on one of the CPUs managed by this structure. Such tasks
will be queued on this structure's ->blkd_tasks list. Only after this
list fully drains can this leaf rcu_node structure be ignored, and even
then only if none of its CPUs have come back online in the meantime.
Once that happens, the ->qsmaskinit masks further up the tree will be
updated to exclude this leaf rcu_node structure.
Once the ->qsmaskinitnext and ->qsmaskinit fields have been updated
as needed, the GP kthread transitions to RCU_GP_INIT.
d. [RCU_GP_INIT] -> [RCU_GP_WAIT_FQS]
The purpose of the RCU_GP_INIT state is to copy each ->qsmaskinit to
the ->qsmask field within each rcu_node structure. This copying is done
breadth-first from the root to the leaves. Why not just copy directly
from ->qsmaskinitnext to ->qsmask? Because the ->qsmaskinitnext masks
can change in the meantime as additional CPUs come online or go offline.
Such changes would result in inconsistencies in the ->qsmask fields up and
down the tree, which could in turn result in too-short grace periods or
grace-period hangs. These issues are avoided by snapshotting the leaf
rcu_node structures' ->qsmaskinitnext fields into their ->qsmaskinit
counterparts, generating a consistent set of ->qsmaskinit fields
throughout the tree, and only then copying these consistent ->qsmaskinit
fields to their ->qsmask counterparts.
Once this initialization step is complete, the GP kthread transitions
to RCU_GP_WAIT_FQS, where it waits to do a force-quiescent-state scan
on the one hand or for the end of the grace period on the other.
e. [RCU_GP_WAIT_FQS] -> [RCU_GP_DOING_FQS]
The RCU_GP_WAIT_FQS state waits for one of three things: (1) An
explicit request to do a force-quiescent-state scan, (2) The end of
the grace period, or (3) A short interval of time, after which it
will do a force-quiescent-state (FQS) scan. The explicit request can
come from rcutorture or from any CPU that has too many RCU callbacks
queued (see the qhimark kernel parameter and the RCU_GP_FLAG_OVLD
flag). The aforementioned "short period of time" is specified by the
jiffies_till_first_fqs boot parameter for a given grace period's first
FQS scan and by the jiffies_till_next_fqs for later FQS scans.
Either way, once the wait is over, the GP kthread transitions to
RCU_GP_DOING_FQS.
f. [RCU_GP_DOING_FQS] -> [RCU_GP_CLEANUP]
The RCU_GP_DOING_FQS state performs an FQS scan. Each such scan carries
out two functions for any CPU whose bit is still set in its leaf rcu_node
structure's ->qsmask field, that is, for any CPU that has not yet reported
a quiescent state for the current grace period:
i. Report quiescent states on behalf of CPUs that have been observed
to be idle (from an RCU perspective) since the beginning of the
grace period.
ii. If the current grace period is too old, take various actions to
encourage holdout CPUs to pass through quiescent states, including
enlisting the aid of any calls to cond_resched() and might_sleep(),
and even including IPIing the holdout CPUs.
These checks are skipped for any leaf rcu_node structure with a all-zero
->qsmask field, however such structures are subject to RCU priority
boosting if there are tasks on a given structure blocking the current
grace period. The end of the grace period is detected when the root
rcu_node structure's ->qsmask is zero and when there are no longer any
preempted tasks blocking the current grace period. (No, this last check
is not redundant. To see this, consider an rcu_node tree having exactly
one structure that serves as both root and leaf.)
Once the end of the grace period is detected, the GP kthread transitions
to RCU_GP_CLEANUP.
g. [RCU_GP_CLEANUP] -> [RCU_GP_CLEANED]
The RCU_GP_CLEANUP state marks the end of grace period by updating the
rcu_state structure's ->gp_seq field and also all rcu_node structures'
->gp_seq field. As before, the rcu_node tree is traversed in breadth
first order. Once this update is complete, the GP kthread transitions
to the RCU_GP_CLEANED state.
i. [RCU_GP_CLEANED] -> [RCU_GP_INIT]
Once in the RCU_GP_CLEANED state, the GP kthread immediately transitions
into the RCU_GP_INIT state.
j. The role of timers.
If there is at least one idle CPU, and if timers are not firing, the
transition from RCU_GP_DOING_FQS to RCU_GP_CLEANUP will never happen.
Timers can fail to fire for a number of reasons, including issues in
timer configuration, issues in the timer framework, and failure to handle
softirqs (for example, when there is a storm of interrupts). Whatever the
reason, if the timers fail to fire, the GP kthread will never be awakened,
resulting in RCU CPU stall warnings and eventually in OOM.
However, an RCU CPU stall warning has a large number of potential causes,
as documented in Documentation/RCU/stallwarn.rst. This commit therefore
adds analysis to the RCU CPU stall-warning code to emit an additional
message if the cause of the stall is likely to be timer failure.
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Because the need to wake a nocb GP kthread ("rcuog") is sometimes
detected when wakeups cannot be done, these wakeups can be deferred.
The wakeups are then carried out by calls to do_nocb_deferred_wakeup()
at various safe points in the code, including RCU's idle hooks. However,
when a CPU goes offline, it invokes arch_cpu_idle_dead() without invoking
any of RCU's idle hooks.
This commit therefore adds a call to do_nocb_deferred_wakeup() in
rcu_report_dead() in order to handle any deferred wakeups that have been
requested by the outgoing CPU.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit addresses a few code-style nits in callback-offloading
toggling, including one that predates this toggling.
Cc: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit improves debuggability by indicating laying out the order
in which rcuoc kthreads appear in the ->nocb_next_cb_rdp list.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit improves debuggability by indicating which grace period each
batch of nocb callbacks is waiting on and by showing the task state and
last CPU for reach nocb kthread.
[ paulmck: Handle !SMP CB offloading per kernel test robot feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Frederic Weisbecker is adding the ability to change the rcu_nocbs state
of CPUs at runtime, that is, to offload and deoffload their RCU callback
processing without the need to reboot. As the old saying goes, "if it
ain't tested, it don't work", so this commit therefore adds prototype
rcutorture testing for this capability.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
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This commit adds a timer_curr_running() function that verifies that the
current code is running in the context of the specified timer's handler.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds a lockdep_is_cpus_held() function to verify that the
proper locks are held and that various operations are running in the
correct context.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The local callbacks processing checks if any callbacks need acceleration.
This commit carries out this checking under nocb lock protection in
the middle of toggle operations, during which time rcu_core() executes
concurrently with GP/CB kthreads.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit makes sure to process the callbacks locally (via either
RCU_SOFTIRQ or the rcuc kthread) whenever the segcblist isn't entirely
offloaded. This ensures that callbacks are invoked one way or another
while a CPU is in the middle of a toggle operation.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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During a toggle operations, rcu_do_batch() may be invoked concurrently
by softirqs and offloaded processing for a given CPU's callbacks.
This commit therefore makes sure cond_resched() is invoked only from
the offloaded context.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit sets SEGCBLIST_SOFTIRQ_ONLY once toggling is otherwise fully
complete, allowing further RCU callback manipulation to be carried out
locklessly and locally.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit flushes the bypass queue and sets state to avoid its being
refilled before switching to the final de-offloaded state. To avoid
refilling, this commit sets SEGCBLIST_SOFTIRQ_ONLY before re-enabling
IRQs.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit ensures that the nocb timer is shut down before reaching the
final de-offloaded state. The key goal is to prevent the timer handler
from manipulating the callbacks without the protection of the nocb locks.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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To re-offload the callback processing off of a CPU, it is necessary to
clear SEGCBLIST_SOFTIRQ_ONLY, set SEGCBLIST_OFFLOADED, and then notify
both the CB and GP kthreads so that they both set their own bit flag and
start processing the callbacks remotely. The re-offloading worker is
then notified that it can stop the RCU_SOFTIRQ handler (or rcuc kthread,
as the case may be) from processing the callbacks locally.
Ordering must be carefully enforced so that the callbacks that used to be
processed locally without locking will have the same ordering properties
when they are invoked by the nocb CB and GP kthreads.
This commit makes this change.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
[ paulmck: Export rcu_nocb_cpu_offload(). ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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To de-offload callback processing back onto a CPU, it is necessary
to clear SEGCBLIST_OFFLOAD and notify the nocb GP kthread, which will
then clear its own bit flag and ignore this CPU until further notice.
Whichever of the nocb CB and nocb GP kthreads is last to clear its own
bit notifies the de-offloading worker kthread. Once notified, this
worker kthread can proceed safe in the knowledge that the nocb CB and
GP kthreads will no longer be manipulating this CPU's RCU callback list.
This commit makes this change.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Offloaded CPUs do not migrate their callbacks, instead relying on
their rcuo kthread to invoke them. But if the CPU is offline, it
will be running neither its RCU_SOFTIRQ handler nor its rcuc kthread.
This means that de-offloading an offline CPU that still has pending
callbacks will strand those callbacks. This commit therefore refuses
to toggle offline CPUs having pending callbacks.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Suggested-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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To de-offload callback processing back onto a CPU, it is necessary to
clear SEGCBLIST_OFFLOAD and notify the nocb CB kthread, which will then
clear its own bit flag and go to sleep to stop handling callbacks. This
commit makes that change. It will also be necessary to notify the nocb
GP kthread in this same way, which is the subject of a follow-on commit.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
[ paulmck: Add export per kernel test robot feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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How the rdp->cblist enabled state is treated at CPU-hotplug time depends
on whether or not that ->cblist is offloaded.
1) Not offloaded: The ->cblist is disabled when the CPU goes down. All
its callbacks are migrated and none can to enqueued until after some
later CPU-hotplug operation brings the CPU back up.
2) Offloaded: The ->cblist is not disabled on CPU down because the CB/GP
kthreads must finish invoking the remaining callbacks. There is thus
no need to re-enable it on CPU up.
Since the ->cblist offloaded state is set in stone at boot, it cannot
change between CPU down and CPU up. So 1) and 2) are symmetrical.
However, given runtime toggling of the offloaded state, there are two
additional asymmetrical scenarios:
3) The ->cblist is not offloaded when the CPU goes down. The ->cblist
is later toggled to offloaded and then the CPU comes back up.
4) The ->cblist is offloaded when the CPU goes down. The ->cblist is
later toggled to no longer be offloaded and then the CPU comes back up.
Scenario 4) is currently handled correctly. The ->cblist remains enabled
on CPU down and gets re-initialized on CPU up. The toggling operation
will wait until ->cblist is empty, so ->cblist will remain empty until
CPU-up time.
The scenario 3) would run into trouble though, as the rdp is disabled
on CPU down and not re-initialized/re-enabled on CPU up. Except that
in this case, ->cblist is guaranteed to be empty because all its
callbacks were migrated away at CPU-down time. And the CPU-up code
already initializes and enables any empty ->cblist structures in order
to handle the possibility of early-boot invocations of call_rcu() in
the case where such invocations don't occur. So all that need be done
is to adjust the locking.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Offloading and de-offloading RCU callback processes must be done
carefully. There must never be a time at which callback processing is
disabled because the task driving the offloading or de-offloading might be
preempted or otherwise stalled at that point in time, which would result
in OOM due to calbacks piling up indefinitely. This implies that there
will be times during which a given CPU's callbacks might be concurrently
invoked by both that CPU's RCU_SOFTIRQ handler (or, equivalently, that
CPU's rcuc kthread) and by that CPU's rcuo kthread.
This situation could fatally confuse both rcu_barrier() and the
CPU-hotplug offlining process, so these must be excluded during any
concurrent-callback-invocation period. In addition, during times of
concurrent callback invocation, changes to ->cblist must be protected
both as needed for RCU_SOFTIRQ and as needed for the rcuo kthread.
This commit therefore defines and documents the states for a state
machine that coordinates offloading and deoffloading.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit gathers the rcu_segcblist ->enabled and ->offloaded property
field into a single ->flags bitmask to avoid further proliferation of
individual u8 fields in the structure. This change prepares for the
state formerly known as ->offloaded state to be modified at runtime.
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Inspired-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds debug checks near the end of rcu_do_batch() that emit
warnings if an empty rcu_segcblist structure has non-zero segment counts,
or, conversely, if a non-empty structure has all-zero segment counts.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
[ paulmck: Fix queue/segment-length checks. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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This commit adds tracing to track how the segcb list changes before/after
acceleration, during queuing and during dequeuing.
This tracing helped discover an optimization that avoided needless GP
requests when no callbacks were accelerated. The tracing overhead is
minimal as each segment's length is now stored in the respective segment.
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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The full memory barriers in rcu_segcblist_enqueue() and in rcu_do_batch()
are not needed because rcu_segcblist_add_len(), and thus also
rcu_segcblist_inc_len(), already includes a memory barrier *before*
and *after* the length of the list is updated.
This commit therefore removes these redundant smp_mb() invocations.
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Add counting of segment lengths of segmented callback list.
This will be useful for a number of things such as knowing how big the
ready-to-execute segment have gotten. The immediate benefit is ability
to trace how the callbacks in the segmented callback list change.
Also this patch remove hacks related to using donecbs's ->len field as a
temporary variable to save the segmented callback list's length. This cannot be
done anymore and is not needed.
Also fix SRCU:
The negative counting of the unsegmented list cannot be used to adjust
the segmented one. To fix this, sample the unsegmented length in
advance, and use it after CB execution to adjust the segmented list's
length.
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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One counter-intuitive property of RCU is the fact that full memory
barriers are needed both before and after updates to the full
(non-segmented) length. This patch therefore helps to assist the
reader's intuition by adding appropriate comments.
[ paulmck: Wordsmithing. ]
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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With commit e722a295cf49 ("staging: ion: remove from the tree"), ION and
its corresponding config CONFIG_ION is gone. Remove stale references
from drivers/staging/media/atomisp/pci and from the recommended Android
kernel config.
Fixes: e722a295cf49 ("staging: ion: remove from the tree")
Cc: Hridya Valsaraju <hridya@google.com>
Cc: Rob Herring <robh@kernel.org>
Cc: linux-media@vger.kernel.org
Cc: devel@driverdev.osuosl.org
Signed-off-by: Matthias Maennich <maennich@google.com>
Link: https://lore.kernel.org/r/20210106155201.2845319-1-maennich@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Preparations to doing i386 compat elf_prstatus sanely - rather than duplicating
the beginning of compat_elf_prstatus, take these fields into a separate
structure (compat_elf_prstatus_common), so that it could be reused. Due to
the incestous relationship between binfmt_elf.c and compat_binfmt_elf.c we
need the same shape change done to native struct elf_prstatus, gathering the
fields prior to pr_reg into a new structure (struct elf_prstatus_common).
Fortunately, offset of pr_reg is always a multiple of 16 with no padding
right before it, so it's possible to turn all the stuff prior to it into
a single member without disturbing the layout.
[build fix from Geert Uytterhoeven folded in]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Pull networking fixes from Jakub Kicinski:
"Networking fixes, including fixes from netfilter, wireless and bpf
trees.
Current release - regressions:
- mt76: fix NULL pointer dereference in mt76u_status_worker and
mt76s_process_tx_queue
- net: ipa: fix interconnect enable bug
Current release - always broken:
- netfilter: fixes possible oops in mtype_resize in ipset
- ath11k: fix number of coding issues found by static analysis tools
and spurious error messages
Previous releases - regressions:
- e1000e: re-enable s0ix power saving flows for systems with the
Intel i219-LM Ethernet controllers to fix power use regression
- virtio_net: fix recursive call to cpus_read_lock() to avoid a
deadlock
- ipv4: ignore ECN bits for fib lookups in fib_compute_spec_dst()
- sysfs: take the rtnl lock around XPS configuration
- xsk: fix memory leak for failed bind and rollback reservation at
NETDEV_TX_BUSY
- r8169: work around power-saving bug on some chip versions
Previous releases - always broken:
- dcb: validate netlink message in DCB handler
- tun: fix return value when the number of iovs exceeds MAX_SKB_FRAGS
to prevent unnecessary retries
- vhost_net: fix ubuf refcount when sendmsg fails
- bpf: save correct stopping point in file seq iteration
- ncsi: use real net-device for response handler
- neighbor: fix div by zero caused by a data race (TOCTOU)
- bareudp: fix use of incorrect min_headroom size and a false
positive lockdep splat from the TX lock
- mvpp2:
- clear force link UP during port init procedure in case
bootloader had set it
- add TCAM entry to drop flow control pause frames
- fix PPPoE with ipv6 packet parsing
- fix GoP Networking Complex Control config of port 3
- fix pkt coalescing IRQ-threshold configuration
- xsk: fix race in SKB mode transmit with shared cq
- ionic: account for vlan tag len in rx buffer len
- stmmac: ignore the second clock input, current clock framework does
not handle exclusive clock use well, other drivers may reconfigure
the second clock
Misc:
- ppp: change PPPIOCUNBRIDGECHAN ioctl request number to follow
existing scheme"
* tag 'net-5.11-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (99 commits)
net: dsa: lantiq_gswip: Fix GSWIP_MII_CFG(p) register access
net: dsa: lantiq_gswip: Enable GSWIP_MII_CFG_EN also for internal PHYs
net: lapb: Decrease the refcount of "struct lapb_cb" in lapb_device_event
r8169: work around power-saving bug on some chip versions
net: usb: qmi_wwan: add Quectel EM160R-GL
selftests: mlxsw: Set headroom size of correct port
net: macb: Correct usage of MACB_CAPS_CLK_HW_CHG flag
ibmvnic: fix: NULL pointer dereference.
docs: networking: packet_mmap: fix old config reference
docs: networking: packet_mmap: fix formatting for C macros
vhost_net: fix ubuf refcount incorrectly when sendmsg fails
bareudp: Fix use of incorrect min_headroom size
bareudp: set NETIF_F_LLTX flag
net: hdlc_ppp: Fix issues when mod_timer is called while timer is running
atlantic: remove architecture depends
erspan: fix version 1 check in gre_parse_header()
net: hns: fix return value check in __lb_other_process()
net: sched: prevent invalid Scell_log shift count
net: neighbor: fix a crash caused by mod zero
ipv4: Ignore ECN bits for fib lookups in fib_compute_spec_dst()
...
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Replace a comma between expression statements by a semicolon.
Signed-off-by: Zheng Yongjun <zhengyongjun3@huawei.com>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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Tasks Trace RCU uses irq_work_queue() to safely awaken its grace-period
kthread, so this commit therefore causes the TASKS_TRACE_RCU Kconfig
option select the IRQ_WORK Kconfig option.
Reported-by: kernel test robot <lkp@intel.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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