11 Jun, 2013
3 commits
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Now that TINY_PREEMPT_RCU is no more, exit_rcu() is always an empty
function. But if TINY_RCU is going to have an empty function, it should
be in include/linux/rcutiny.h, where it does not bloat the kernel.
This commit therefore moves exit_rcu() out of kernel/rcupdate.c to
kernel/rcutree_plugin.h, and places a static inline empty function in
include/linux/rcutiny.h in order to shrink TINY_RCU a bit.Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett -
TINY_PREEMPT_RCU could use a kthread to handle RCU callback invocation,
which required an API to abstract kthread vs. softirq invocation.
Now that TINY_PREEMPT_RCU is no longer with us, this commit retires
this API in favor of direct use of the relevant softirq primitives.Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett -
TINY_PREEMPT_RCU adds significant code and complexity, but does not
offer commensurate benefits. People currently using TINY_PREEMPT_RCU
can get much better memory footprint with TINY_RCU, or, if they really
need preemptible RCU, they can use TREE_PREEMPT_RCU with a relatively
minor degradation in memory footprint. Please note that this move
has been widely publicized on LKML (https://lkml.org/lkml/2012/11/12/545)
and on LWN (http://lwn.net/Articles/541037/).This commit therefore removes TINY_PREEMPT_RCU.
Signed-off-by: Paul E. McKenney
[ paulmck: Updated to eliminate #else in rcutiny.h as suggested by Josh ]
Reviewed-by: Josh Triplett
29 May, 2013
1 commit
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As rcu_dereference_raw() under RCU debug config options can add quite a
bit of checks, and that tracing uses rcu_dereference_raw(), these checks
happen with the function tracer. The function tracer also happens to trace
these debug checks too. This added overhead can livelock the system.Add a new interface to RCU for both rcu_dereference_raw_notrace() as well
as hlist_for_each_entry_rcu_notrace() as the hlist iterator uses the
rcu_dereference_raw() as well, and is used a bit with the function tracer.Link: http://lkml.kernel.org/r/20130528184209.304356745@goodmis.org
Acked-by: Paul E. McKenney
Signed-off-by: Steven Rostedt
02 May, 2013
1 commit
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The full dynticks tree needs the latest RCU and sched
upstream updates in order to fix some dependencies.Merge a common upstream merge point that has these
updates.Conflicts:
include/linux/perf_event.h
kernel/rcutree.h
kernel/rcutree_plugin.hSigned-off-by: Frederic Weisbecker
19 Apr, 2013
1 commit
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We need full dynticks CPU to also be RCU nocb so
that we don't have to keep the tick to handle RCU
callbacks.Make sure the range passed to nohz_full= boot
parameter is a subset of rcu_nocbs=The CPUs that fail to meet this requirement will be
excluded from the nohz_full range. This is checked
early in boot time, before any CPU has the opportunity
to stop its tick.Suggested-by: Steven Rostedt
Reviewed-by: Paul E. McKenney
Signed-off-by: Frederic Weisbecker
Cc: Andrew Morton
Cc: Chris Metcalf
Cc: Christoph Lameter
Cc: Geoff Levand
Cc: Gilad Ben Yossef
Cc: Hakan Akkan
Cc: Ingo Molnar
Cc: Kevin Hilman
Cc: Li Zhong
Cc: Paul E. McKenney
Cc: Paul Gortmaker
Cc: Peter Zijlstra
Cc: Steven Rostedt
Cc: Thomas Gleixner
26 Mar, 2013
1 commit
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Because RCU callbacks are now associated with the number of the grace
period that they must wait for, CPUs can now take advance callbacks
corresponding to grace periods that ended while a given CPU was in
dyntick-idle mode. This eliminates the need to try forcing the RCU
state machine while entering idle, thus reducing the CPU intensiveness
of RCU_FAST_NO_HZ, which should increase its energy efficiency.Signed-off-by: Paul E. McKenney
Signed-off-by: Paul E. McKenney
29 Jan, 2013
1 commit
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…' and 'tiny.2013.01.29b' into HEAD
doctorture.2013.01.11a: Changes to rcutorture and to RCU documentation.
fixes.2013.01.26a: Miscellaneous fixes.
tagcb.2013.01.24a: Tag RCU callbacks with grace-period number to
simplify callback advancement.tiny.2013.01.29b: Enhancements to uniprocessor handling in tiny RCU.
27 Jan, 2013
1 commit
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Signed-off-by: Paul E. McKenney
09 Jan, 2013
1 commit
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Currently, rcutorture traces every read-side access. This can be
problematic because even a two-minute rcutorture run on a two-CPU system
can generate 28,853,363 reads. Normally, only a failing read is of
interest, so this commit traces adjusts rcutorture's tracing to only
trace failing reads. The resulting event tracing records the time
and the ->completed value captured at the beginning of the RCU read-side
critical section, allowing correlation with other event-tracing messages.Signed-off-by: Paul E. McKenney
Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett
[ paulmck: Add fix to build problem located by Randy Dunlap based on
diagnosis by Steven Rostedt. ]
01 Dec, 2012
1 commit
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Create a new subsystem that probes on kernel boundaries
to keep track of the transitions between level contexts
with two basic initial contexts: user or kernel.This is an abstraction of some RCU code that use such tracking
to implement its userspace extended quiescent state.We need to pull this up from RCU into this new level of indirection
because this tracking is also going to be used to implement an "on
demand" generic virtual cputime accounting. A necessary step to
shutdown the tick while still accounting the cputime.Signed-off-by: Frederic Weisbecker
Cc: Andrew Morton
Cc: H. Peter Anvin
Cc: Ingo Molnar
Cc: Paul E. McKenney
Cc: Peter Zijlstra
Cc: Steven Rostedt
Cc: Thomas Gleixner
Cc: Li Zhong
Cc: Gilad Ben-Yossef
Reviewed-by: Steven Rostedt
[ paulmck: fix whitespace error and email address. ]
Signed-off-by: Paul E. McKenney
17 Nov, 2012
1 commit
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…cu.2012.10.27a', 'stall.2012.11.13a', 'tracing.2012.11.08a' and 'idle.2012.10.24a' into HEAD
urgent.2012.10.27a: Fix for RCU user-mode transition (already in -tip).
doc.2012.11.08a: Documentation updates, most notably codifying the
memory-barrier guarantees inherent to grace periods.fixes.2012.11.13a: Miscellaneous fixes.
srcu.2012.10.27a: Allow statically allocated and initialized srcu_struct
structures (courtesy of Lai Jiangshan).stall.2012.11.13a: Add more diagnostic information to RCU CPU stall
warnings, also decrease from 60 seconds to 21 seconds.hotplug.2012.11.08a: Minor updates to CPU hotplug handling.
tracing.2012.11.08a: Improved debugfs tracing, courtesy of Michael Wang.
idle.2012.10.24a: Updates to RCU idle/adaptive-idle handling, including
a boot parameter that maps normal grace periods to expedited.Resolved conflict in kernel/rcutree.c due to side-by-side change.
14 Nov, 2012
1 commit
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This commit explicitly states the memory-ordering properties of the
RCU grace-period primitives. Although these properties were in some
sense implied by the fundmental property of RCU ("a grace period must
wait for all pre-existing RCU read-side critical sections to complete"),
stating it explicitly will be a great labor-saving device.Reported-by: Oleg Nesterov
Signed-off-by: Paul E. McKenney
Reviewed-by: Oleg Nesterov
24 Oct, 2012
1 commit
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It's only there to call rcu_user_hooks_switch(). Let's
just call rcu_user_hooks_switch() directly, we don't need this
function in the middle.Signed-off-by: Frederic Weisbecker
Cc: Josh Triplett
Cc: Peter Zijlstra
Cc: Richard Weinberger
Signed-off-by: Paul E. McKenney
26 Sep, 2012
4 commits
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Clear the syscalls hook of a task when it's scheduled out so that if
the task migrates, it doesn't run the syscall slow path on a CPU
that might not need it.Also set the syscalls hook on the next task if needed.
Signed-off-by: Frederic Weisbecker
Cc: Alessio Igor Bogani
Cc: Andrew Morton
Cc: Avi Kivity
Cc: Chris Metcalf
Cc: Christoph Lameter
Cc: Geoff Levand
Cc: Gilad Ben Yossef
Cc: Hakan Akkan
Cc: H. Peter Anvin
Cc: Ingo Molnar
Cc: Josh Triplett
Cc: Kevin Hilman
Cc: Max Krasnyansky
Cc: Peter Zijlstra
Cc: Stephen Hemminger
Cc: Steven Rostedt
Cc: Sven-Thorsten Dietrich
Cc: Thomas Gleixner
Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett -
Create a new config option under the RCU menu that put
CPUs under RCU extended quiescent state (as in dynticks
idle mode) when they run in userspace. This require
some contribution from architectures to hook into kernel
and userspace boundaries.Signed-off-by: Frederic Weisbecker
Cc: Alessio Igor Bogani
Cc: Andrew Morton
Cc: Avi Kivity
Cc: Chris Metcalf
Cc: Christoph Lameter
Cc: Geoff Levand
Cc: Gilad Ben Yossef
Cc: Hakan Akkan
Cc: H. Peter Anvin
Cc: Ingo Molnar
Cc: Josh Triplett
Cc: Kevin Hilman
Cc: Max Krasnyansky
Cc: Peter Zijlstra
Cc: Stephen Hemminger
Cc: Steven Rostedt
Cc: Sven-Thorsten Dietrich
Cc: Thomas Gleixner
Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett -
In some cases, it is necessary to enter or exit userspace-RCU-idle mode
from an interrupt handler, for example, if some other CPU sends this
CPU a resched IPI. In this case, the current CPU would enter the IPI
handler in userspace-RCU-idle mode, but would need to exit the IPI handler
after having exited that mode.To allow this to work, this commit adds two new APIs to TREE_RCU:
- rcu_user_enter_after_irq(). This must be called from an interrupt between
rcu_irq_enter() and rcu_irq_exit(). After the irq calls rcu_irq_exit(),
the irq handler will return into an RCU extended quiescent state.
In theory, this interrupt is never a nested interrupt, but in practice
it might interrupt softirq, which looks to RCU like a nested interrupt.- rcu_user_exit_after_irq(). This must be called from a non-nesting
interrupt, interrupting an RCU extended quiescent state, also
between rcu_irq_enter() and rcu_irq_exit(). After the irq calls
rcu_irq_exit(), the irq handler will return in an RCU non-quiescent
state.[ Combined with "Allow calls to rcu_exit_user_irq from nesting irqs." ]
Signed-off-by: Frederic Weisbecker
Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett -
RCU currently insists that only idle tasks can enter RCU idle mode, which
prohibits an adaptive tickless kernel (AKA nohz cpusets), which in turn
would mean that usermode execution would always take scheduling-clock
interrupts, even when there is only one task runnable on the CPU in
question.This commit therefore adds rcu_user_enter() and rcu_user_exit(), which
allow non-idle tasks to enter RCU idle mode. These are quite similar
to rcu_idle_enter() and rcu_idle_exit(), respectively, except that they
omit the idle-task checks.[ Updated to use "user" flag rather than separate check functions. ]
[ paulmck: Updated to drop exports of new functions based on Josh's patch
getting rid of the need for them. ]Signed-off-by: Frederic Weisbecker
Signed-off-by: Paul E. McKenney
Cc: Alessio Igor Bogani
Cc: Andrew Morton
Cc: Avi Kivity
Cc: Chris Metcalf
Cc: Christoph Lameter
Cc: Daniel Lezcano
Cc: Geoff Levand
Cc: Gilad Ben Yossef
Cc: Hakan Akkan
Cc: Ingo Molnar
Cc: Kevin Hilman
Cc: Max Krasnyansky
Cc: Peter Zijlstra
Cc: Stephen Hemminger
Cc: Steven Rostedt
Cc: Sven-Thorsten Dietrich
Cc: Thomas Gleixner
Reviewed-by: Josh Triplett
23 Sep, 2012
1 commit
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There is a need to use RCU from interrupt context, but either before
rcu_irq_enter() is called or after rcu_irq_exit() is called. If the
interrupt occurs from idle, then lockdep-RCU will complain about such
uses, as they appear to be illegal uses of RCU from the idle loop.
In other environments, RCU_NONIDLE() could be used to properly protect
the use of RCU, but RCU_NONIDLE() currently cannot be invoked except
from process context.This commit therefore modifies RCU_NONIDLE() to permit its use more
globally.Reported-by: Steven Rostedt
Signed-off-by: Paul E. McKenney
Signed-off-by: Paul E. McKenney
06 Jul, 2012
2 commits
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Although the C language allows you to break strings across lines, doing
this makes it hard for people to find the Linux kernel code corresponding
to a given console message. This commit therefore fixes broken strings
throughout RCU's source code.Suggested-by: Josh Triplett
Suggested-by: Ingo Molnar
Signed-off-by: Paul E. McKenney -
…a' and 'fnh.2012.07.02a' into HEAD
bigrtm: First steps towards getting RCU out of the way of
tens-of-microseconds real-time response on systems compiled
with NR_CPUS=4096. Also cleanups for and increased concurrency
of rcu_barrier() family of primitives.
doctorture: rcutorture and documentation improvements.
fixes: Miscellaneous fixes.
fnh: RCU_FAST_NO_HZ fixes and improvements.
03 Jul, 2012
8 commits
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Commit d8169d4c (Make __kfree_rcu() less dependent on compiler choices)
created a macro out of an inline function in order to avoid build
breakage for certain combinations of gcc flags. Unfortunately, it also
converted a kfree_call_rcu() to a call_rcu(), which made the rcu_data
structure's ->qlen_lazy field lose counts. This commit therefore changes
the call_rcu() back to kfree_call_rcu().Signed-off-by: Paul E. McKenney
Signed-off-by: Paul E. McKenney -
Although __call_rcu() is handled correctly when called from a momentary
non-idle period, if it is called on a CPU that RCU believes to be idle
on RCU_FAST_NO_HZ kernels, the callback might be indefinitely postponed.
This commit therefore ensures that RCU is aware of the new callback and
has a chance to force the CPU out of dyntick-idle mode when a new callback
is posted.Reported-by: Frederic Weisbecker
Signed-off-by: Paul E. McKenney
Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett -
Commit d8169d4c (Make __kfree_rcu() less dependent on compiler choices)
added cpp macro versions of __kfree_rcu() and __is_kfree_rcu_offset(),
but failed to remove the old inline-function versions. This commit does
this cleanup.Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett -
The CONFIG_TREE_PREEMPT_RCU and CONFIG_TINY_PREEMPT_RCU versions of
__rcu_read_lock() and __rcu_read_unlock() are identical, so this commit
consolidates them into kernel/rcupdate.h.Signed-off-by: Paul E. McKenney
Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett -
The return value from rcu_assign_pointer() is not used, and using it
would be quite ugly, for example:q = rcu_assign_pointer(global_p, p);
To prevent this sort of ugliness from spreading, this commit wraps
rcu_assign_pointer() in a do-while loop.Reported-by: Mathieu Desnoyers
Reported-by: Josh Triplett
Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett -
The return value from RCU_INIT_POINTER() is not used, and using it
would be quite ugly, for example:q = RCU_INIT_POINTER(global_p, p);
To prevent this sort of ugliness from appearing, this commit wraps
RCU_INIT_POINTER() in a do-while loop.Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett
Acked-by: David Howells -
RCU_INIT_POINTER() returns a value that is never used, and which should
be abolished due to terminal ugliness:q = RCU_INIT_POINTER(global_p, p);
However, there are two uses that cannot be handled by a do-while
formulation because they do gcc-style initialization:RCU_INIT_POINTER(.real_cred, &init_cred),
RCU_INIT_POINTER(.cred, &init_cred),This usage is clever, but not necessarily the nicest approach.
This commit therefore creates an RCU_POINTER_INITIALIZER() macro that
is specifically designed for gcc-style initialization.Signed-off-by: Paul E. McKenney
Acked-by: David Howells -
This reverts commit 616c310e83b872024271c915c1b9ab505b9efad9.
(Move PREEMPT_RCU preemption to switch_to() invocation).
Testing by Sasha Levin showed that this
can result in deadlock due to invoking the scheduler when one of
the runqueue locks is held. Because this commit was simply a
performance optimization, revert it.Reported-by: Sasha Levin
Signed-off-by: Paul E. McKenney
Tested-by: Sasha Levin
12 May, 2012
1 commit
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…and 'srcu.2012.05.07b' into HEAD
barrier: Reduce the amount of disturbance by rcu_barrier() to the rest of
the system. This branch also includes improvements to
RCU_FAST_NO_HZ, which are included here due to conflicts.
fixes: Miscellaneous fixes.
inline: Remaining changes from an abortive attempt to inline
preemptible RCU's __rcu_read_lock(). These are (1) making
exit_rcu() avoid unnecessary work and (2) avoiding having
preemptible RCU record a blocked thread when the scheduler
declines to do a context switch.
srcu: Lai Jiangshan's algorithmic implementation of SRCU, including
call_srcu().
03 May, 2012
2 commits
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When running preemptible RCU, if a task exits in an RCU read-side
critical section having blocked within that same RCU read-side critical
section, the task must be removed from the list of tasks blocking a
grace period (perhaps the current grace period, perhaps the next grace
period, depending on timing). The exit() path invokes exit_rcu() to
do this cleanup.However, the current implementation of exit_rcu() needlessly does the
cleanup even if the task did not block within the current RCU read-side
critical section, which wastes time and needlessly increases the size
of the state space. Fix this by only doing the cleanup if the current
task is actually on the list of tasks blocking some grace period.While we are at it, consolidate the two identical exit_rcu() functions
into a single function.Signed-off-by: Paul E. McKenney
Signed-off-by: Paul E. McKenney
Tested-by: Linus TorvaldsConflicts:
kernel/rcupdate.c
-
Currently, PREEMPT_RCU readers are enqueued upon entry to the scheduler.
This is inefficient because enqueuing is required only if there is a
context switch, and entry to the scheduler does not guarantee a context
switch.The commit therefore moves the enqueuing to immediately precede the
call to switch_to() from the scheduler.Signed-off-by: Paul E. McKenney
Signed-off-by: Paul E. McKenney
Tested-by: Linus Torvalds
25 Apr, 2012
1 commit
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Currently, __kfree_rcu() is implemented as an inline function, and
contains a BUILD_BUG_ON() that malfunctions if __kfree_rcu() is compiled
as an out-of-line function. Unfortunately, there are compiler settings
(e.g., -O0) that can result in __kfree_rcu() being compiled out of line,
resulting in annoying build breakage. This commit therefore converts
both __kfree_rcu() and __is_kfree_rcu_offset() from inline functions to
macros to prevent such misbehavior on the part of the compiler.Signed-off-by: Jan Engelhardt
Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett
25 Mar, 2012
1 commit
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Pull cleanup from Paul Gortmaker:
"The changes shown here are to unify linux's BUG support under the one
file. Due to historical reasons, we have some BUG code
in bug.h and some in kernel.h -- i.e. the support for BUILD_BUG in
linux/kernel.h predates the addition of linux/bug.h, but old code in
kernel.h wasn't moved to bug.h at that time. As a band-aid, kernel.h
was including to pseudo link them.This has caused confusion[1] and general yuck/WTF[2] reactions. Here
is an example that violates the principle of least surprise:CC lib/string.o
lib/string.c: In function 'strlcat':
lib/string.c:225:2: error: implicit declaration of function 'BUILD_BUG_ON'
make[2]: *** [lib/string.o] Error 1
$
$ grep linux/bug.h lib/string.c
#include
$We've included for the BUG infrastructure and yet we
still get a compile fail! [We've not kernel.h for BUILD_BUG_ON.] Ugh -
very confusing for someone who is new to kernel development.With the above in mind, the goals of this changeset are:
1) find and fix any include/*.h files that were relying on the
implicit presence of BUG code.
2) find and fix any C files that were consuming kernel.h and hence
relying on implicitly getting some/all BUG code.
3) Move the BUG related code living in kernel.h to
4) remove the asm/bug.h from kernel.h to finally break the chain.During development, the order was more like 3-4, build-test, 1-2. But
to ensure that git history for bisect doesn't get needless build
failures introduced, the commits have been reorderd to fix the problem
areas in advance.[1] https://lkml.org/lkml/2012/1/3/90
[2] https://lkml.org/lkml/2012/1/17/414"Fix up conflicts (new radeon file, reiserfs header cleanups) as per Paul
and linux-next.* tag 'bug-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux:
kernel.h: doesn't explicitly use bug.h, so don't include it.
bug: consolidate BUILD_BUG_ON with other bug code
BUG: headers with BUG/BUG_ON etc. need linux/bug.h
bug.h: add include of it to various implicit C users
lib: fix implicit users of kernel.h for TAINT_WARN
spinlock: macroize assert_spin_locked to avoid bug.h dependency
x86: relocate get/set debugreg fcns to include/asm/debugreg.
24 Mar, 2012
1 commit
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Due to the alignment of following variables, these typically consume
more than just the single byte that 'bool' requires, and as there are a
few hundred instances, the cache pollution (not so much the waste of
memory) sums up. Put these variables into their own section, outside of
any half way frequently used memory range.Do the same also to the __warned variable of rcu_lockdep_assert().
(Don't, however, include the ones used by printk_once() and alike, as
they can potentially be hot.)Signed-off-by: Jan Beulich
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
05 Mar, 2012
1 commit
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If a header file is making use of BUG, BUG_ON, BUILD_BUG_ON, or any
other BUG variant in a static inline (i.e. not in a #define) then
that header really should be including and not just
expecting it to be implicitly present.We can make this change risk-free, since if the files using these
headers didn't have exposure to linux/bug.h already, they would have
been causing compile failures/warnings.Signed-off-by: Paul Gortmaker
22 Feb, 2012
4 commits
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RCU, RCU-bh, and RCU-sched read-side critical sections are forbidden
in the inner idle loop, that is, between the rcu_idle_enter() and the
rcu_idle_exit() -- RCU will happily ignore any such read-side critical
sections. However, things like powertop need tracepoints in the inner
idle loop.This commit therefore provides an RCU_NONIDLE() macro that can be used to
wrap code in the idle loop that requires RCU read-side critical sections.Suggested-by: Steven Rostedt
Signed-off-by: Paul E. McKenney
Signed-off-by: Paul E. McKenney
Reviewed-by: Josh Triplett
Acked-by: Deepthi Dharwar -
The WARN_ON_ONCE() in rcu_lock_acquire() results in infinite recursion
on S390, and also doesn't print very much information. Remove this.Updated patch to add lockdep-RCU assertions to RCU's read-side primitives.
Signed-off-by: Heiko Carstens
Signed-off-by: Paul E. McKenney -
Although it is legal to use RCU during early boot, it is anything
but legal to use RCU at runtime from an offlined CPU. After all, RCU
explicitly ignores offlined CPUs. This commit therefore adds checks
for runtime use of RCU from offlined CPUs.These checks are not perfect, in particular, they can be subverted
through use of things like rcu_dereference_raw(). Note that it is not
possible to put checks in rcu_read_lock() and friends due to the fact
that these primitives are used in code that might be used under either
RCU or lock-based protection, which means that checking rcu_read_lock()
gets you fat piles of false positives.Signed-off-by: Paul E. McKenney
Signed-off-by: Paul E. McKenney -
There is no convenient expression for rcu_deference_protected()
when it is used in tearing down multilinked structures following
a grace period. For example, suppose that an element containing an
RCU-protected pointer to a second element is removed from an enclosing
RCU-protected data structure, then the write-side lock is released,
and finally synchronize_rcu() is invoked to wait for a grace period.
Then it is necessary to traverse the pointer in order to free up the
second element. But we are not in an RCU read-side critical section
and we are holding no locks, so the usual rcu_dereference_check() and
rcu_dereference_protected() primitives are not appropriate. Neither
is rcu_dereference_raw(), as it is intended for use in data structures
where the user defines the locking design (for example, list_head).So this responsibility is added to rcu_access_pointer()'s list, and
this commit updates rcu_assign_pointer()'s header comment accordingly.Suggested-by: David Howells
Signed-off-by: Paul E. McKenney
Acked-by: David Howells
