summaryrefslogtreecommitdiffstats
path: root/include/linux/rcupdate.h
Commit message (Collapse)AuthorAgeFilesLines
* Merge branch 'core-rcu-for-linus' of ↵Linus Torvalds2014-03-311-46/+48
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull RCU updates from Ingo Molnar: "Main changes: - Torture-test changes, including refactoring of rcutorture and introduction of a vestigial locktorture. - Real-time latency fixes. - Documentation updates. - Miscellaneous fixes" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (77 commits) rcu: Provide grace-period piggybacking API rcu: Ensure kernel/rcu/rcu.h can be sourced/used stand-alone rcu: Fix sparse warning for rcu_expedited from kernel/ksysfs.c notifier: Substitute rcu_access_pointer() for rcu_dereference_raw() Documentation/memory-barriers.txt: Clarify release/acquire ordering rcutorture: Save kvm.sh output to log rcutorture: Add a lock_busted to test the test rcutorture: Place kvm-test-1-run.sh output into res directory rcutorture: Rename TREE_RCU-Kconfig.txt locktorture: Add kvm-recheck.sh plug-in for locktorture rcutorture: Gracefully handle NULL cleanup hooks locktorture: Add vestigial locktorture configuration rcutorture: Introduce "rcu" directory level underneath configs rcutorture: Rename kvm-test-1-rcu.sh rcutorture: Remove RCU dependencies from ver_functions.sh API rcutorture: Create CFcommon file for common Kconfig parameters rcutorture: Create config files for scripted test-the-test testing rcutorture: Add an rcu_busted to test the test locktorture: Add a lock-torture kernel module rcutorture: Abstract kvm-recheck.sh ...
| *-. Merge branches 'doc.2014.02.24a', 'fixes.2014.02.26a' and 'rt.2014.02.17b' ↵Paul E. McKenney2014-02-261-46/+48
| |\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | into HEAD doc.2014.02.24a: Documentation changes fixes.2014.02.26a: Miscellaneous fixes rt.2014.02.17b: Response-time-related changes
| | | * rcu: Optimize rcu_needs_cpu() for RCU_NOCB_CPU_ALLPaul E. McKenney2014-02-171-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If CONFIG_RCU_NOCB_CPU_ALL=y, then rcu_needs_cpu() will always return false, however, the current version nevertheless checks for RCU callbacks. This commit therefore creates a static inline implementation of rcu_needs_cpu() that unconditionally returns false when CONFIG_RCU_NOCB_CPU_ALL=y. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | | * rcu: Optimize rcu_is_nocb_cpu() for RCU_NOCB_CPU_ALLPaul E. McKenney2014-02-171-2/+4
| | |/ | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | If CONFIG_RCU_NOCB_CPU_ALL=y, then rcu_is_nocb_cpu() will always return true, however, the current version nevertheless checks rcu_nocb_mask. This commit therefore creates a static inline implementation of rcu_is_nocb_cpu() that unconditionally returns true when CONFIG_RCU_NOCB_CPU_ALL=y. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * rcu: Fix sparse warning for rcu_expedited from kernel/ksysfs.cPaul Gortmaker2014-02-261-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit fixes the follwoing warning: kernel/ksysfs.c:143:5: warning: symbol 'rcu_expedited' was not declared. Should it be static? Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> [ paulmck: Moved the declaration to include/linux/rcupdate.h to avoid including the RCU-internal rcu.h file outside of RCU. ] Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * rcu: Define rcu_assign_pointer() in terms of smp_store_release()Paul E. McKenney2014-02-171-6/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The new smp_store_release() function provides better guarantees than did rcu_assign_pointer(), and potentially less overhead on some architectures. The guarantee that smp_store_release() provides that rcu_assign_pointer() does that is obscure, but its lack could cause considerable confusion. This guarantee is illustrated by the following code fragment: struct foo { int a; int b; int c; struct foo *next; }; struct foo foo1; struct foo foo2; struct foo __rcu *foop; ... foo2.a = 1; foo2.b = 2; BUG_ON(foo2.c); rcu_assign_pointer(foop, &foo); ... fp = rcu_dereference(foop); fp.c = 3; The current rcu_assign_pointer() semantics permit the BUG_ON() to trigger because rcu_assign_pointer()'s smp_wmb() is not guaranteed to order prior reads against later writes. This commit therefore upgrades rcu_assign_pointer() from smp_wmb() to smp_store_release() to avoid this counter-intuitive outcome. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * rcu: Indentation and spacing fixes.Joe Perches2014-02-171-29/+29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit outdents expression-statement macros, thus repairing a few line-length complaints. Also fix some spacing errors called out by checkpatch.pl. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * rcu: Glue ASCII strings togetherJoe Perches2014-02-171-10/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Split strings make it difficult to find the code that resulted in a given console message, so this commit glues split strings back together despite the resulting long lines. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * rcu: Stop tracking FSF's postal addressPaul E. McKenney2014-02-171-2/+2
| |/ | | | | | | | | | | | | | | | | | | | | | | All of the RCU source files have the usual GPL header, which contains a long-obsolete postal address for FSF. To avoid the need to track the FSF office's movements, this commit substitutes the URL where GPL may be found. Reported-by: Greg KH <gregkh@linuxfoundation.org> Reported-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* / lockdep: Make held_lock->check and "int check" argument boolOleg Nesterov2014-02-091-1/+1
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | The "int check" argument of lock_acquire() and held_lock->check are misleading. This is actually a boolean: 2 means "true", everything else is "false". And there is no need to pass 1 or 0 to lock_acquire() depending on CONFIG_PROVE_LOCKING, __lock_acquire() checks prove_locking at the start and clears "check" if !CONFIG_PROVE_LOCKING. Note: probably we can simply kill this member/arg. The only explicit user of check => 0 is rcu_lock_acquire(), perhaps we can change it to use lock_acquire(trylock =>, read => 2). __lockdep_no_validate means check => 0 implicitly, but we can change validate_chain() to check hlock->instance->key instead. Not to mention it would be nice to get rid of lockdep_set_novalidate_class(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Dave Jones <davej@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/20140120182006.GA26495@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* Merge branch 'for-linus' of ↵Linus Torvalds2014-01-281-2/+0
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs updates from Al Viro: "Assorted stuff; the biggest pile here is Christoph's ACL series. Plus assorted cleanups and fixes all over the place... There will be another pile later this week" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (43 commits) __dentry_path() fixes vfs: Remove second variable named error in __dentry_path vfs: Is mounted should be testing mnt_ns for NULL or error. Fix race when checking i_size on direct i/o read hfsplus: remove can_set_xattr nfsd: use get_acl and ->set_acl fs: remove generic_acl nfs: use generic posix ACL infrastructure for v3 Posix ACLs gfs2: use generic posix ACL infrastructure jfs: use generic posix ACL infrastructure xfs: use generic posix ACL infrastructure reiserfs: use generic posix ACL infrastructure ocfs2: use generic posix ACL infrastructure jffs2: use generic posix ACL infrastructure hfsplus: use generic posix ACL infrastructure f2fs: use generic posix ACL infrastructure ext2/3/4: use generic posix ACL infrastructure btrfs: use generic posix ACL infrastructure fs: make posix_acl_create more useful fs: make posix_acl_chmod more useful ...
| * introduce __fcheck_files() to fix rcu_dereference_check_fdtable(), kill ↵Oleg Nesterov2014-01-251-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | rcu_my_thread_group_empty() rcu_dereference_check_fdtable() looks very wrong, 1. rcu_my_thread_group_empty() was added by 844b9a8707f1 "vfs: fix RCU-lockdep false positive due to /proc" but it doesn't really fix the problem. A CLONE_THREAD (without CLONE_FILES) task can hit the same race with get_files_struct(). And otoh rcu_my_thread_group_empty() can suppress the correct warning if the caller is the CLONE_FILES (without CLONE_THREAD) task. 2. files->count == 1 check is not really right too. Even if this files_struct is not shared it is not safe to access it lockless unless the caller is the owner. Otoh, this check is sub-optimal. files->count == 0 always means it is safe to use it lockless even if files != current->files, but put_files_struct() has to take rcu_read_lock(). See the next patch. This patch removes the buggy checks and turns fcheck_files() into __fcheck_files() which uses rcu_dereference_raw(), the "unshared" callers, fget_light() and fget_raw_light(), can use it to avoid the warning from RCU-lockdep. fcheck_files() is trivially reimplemented as rcu_lockdep_assert() plus __fcheck_files(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| |
| \
*-. \ Merge branches 'doc.2013.12.03a', 'fixes.2013.12.12a', ↵Paul E. McKenney2013-12-121-70/+83
|\ \ \ | |_|/ |/| | | | | | | | | | | | | | | | | | | | 'rcutorture.2013.12.03a' and 'sparse.2013.12.12a' into HEAD doc.2013.12.03a: Topic branch for documentation changes. fixes.2013.12.12a: Topic branch for miscellaneous fixes. rcutorture.2013.12.03a: Topic branch for new rcutorture/KVM scripting. sparse.2013.12.12a: Topic branch for sparse-RCU changes.
| | * rcu: Add an RCU_INITIALIZER for global RCU-protected pointersPaul E. McKenney2013-12-121-38/+42
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is currently no way to initialize a global RCU-protected pointer without either putting up with sparse complaints or open-coding an obscure cast. This commit therefore creates RCU_INITIALIZER(), which is intended to be used as follows: struct foo __rcu *p = RCU_INITIALIZER(&my_rcu_structure); This commit also applies RCU_INITIALIZER() to eliminate repeated open-coded obscure casts in __rcu_assign_pointer(), RCU_INIT_POINTER(), and RCU_POINTER_INITIALIZER(). This commit also inlines __rcu_assign_pointer() into its only caller, rcu_assign_pointer(). Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| | * rcu: Make rcu_assign_pointer's assignment volatile and type-safeJosh Triplett2013-12-121-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | The rcu_assign_pointer() primitive needs to use ACCESS_ONCE to make the assignment to the destination pointer volatile, to protect against compilers too clever for their own good. Signed-off-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| | * rcu: Add comment on evaluate-once properties of rcu_assign_pointer().Paul E. McKenney2013-12-121-0/+8
| |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | The rcu_assign_pointer() macro, as with most cpp macros, must not evaluate its argument more than once. And it in fact does not. But this might not be obvious to the casual observer, because one of the arguments appears no less than three times. However, but one expansion is only visible to sparse (__CHECKER__), and one lives inside a typeof (where it will never be evaluated), so this is in fact safe. This commit therefore adds a comment making this explicit. Reported-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| * rcu: Remove "extern" from function declarations in include/linux/*rcu*.hTeodora Baluta2013-12-121-40/+40
| | | | | | | | | | | | | | | | | | Function prototypes don't need to have the "extern" keyword since this is the default behavior. Its explicit use is redundant. This commit therefore removes them. Signed-off-by: Teodora Baluta <teobaluta@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| * rcu: Provide better diagnostics for blocking in RCU callback functionsPaul E. McKenney2013-12-091-0/+1
|/ | | | | | | | | | Currently blocking in an RCU callback function will result in "scheduling while atomic", which could be triggered for any number of reasons. To aid debugging, this patch introduces a rcu_callback_map that is used to tie the inappropriate voluntary context switch back to the fact that the function is being invoked from within a callback. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Consistent rcu_is_watching() namingPaul E. McKenney2013-09-251-9/+9
| | | | | | | | | The old rcu_is_cpu_idle() function is just __rcu_is_watching() with preemption disabled. This commit therefore renames rcu_is_cpu_idle() to rcu_is_watching. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* rcu: Is it safe to enter an RCU read-side critical section?Paul E. McKenney2013-09-251-4/+4
| | | | | | | | | | | | | | | | | There is currently no way for kernel code to determine whether it is safe to enter an RCU read-side critical section, in other words, whether or not RCU is paying attention to the currently running CPU. Given the large and increasing quantity of code shared by the idle loop and non-idle code, the this shortcoming is becoming increasingly painful. This commit therefore adds __rcu_is_watching(), which returns true if it is safe to enter an RCU read-side critical section on the currently running CPU. This function is quite fast, using only a __this_cpu_read(). However, the caller must disable preemption. Reported-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* nohz_full: Add full-system-idle state machinePaul E. McKenney2013-08-311-0/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit adds the state machine that takes the per-CPU idle data as input and produces a full-system-idle indication as output. This state machine is driven out of RCU's quiescent-state-forcing mechanism, which invokes rcu_sysidle_check_cpu() to collect per-CPU idle state and then rcu_sysidle_report() to drive the state machine. The full-system-idle state is sampled using rcu_sys_is_idle(), which also drives the state machine if RCU is idle (and does so by forcing RCU to become non-idle). This function returns true if all but the timekeeping CPU (tick_do_timer_cpu) are idle and have been idle long enough to avoid memory contention on the full_sysidle_state state variable. The rcu_sysidle_force_exit() may be called externally to reset the state machine back into non-idle state. For large systems the state machine is driven out of RCU's force-quiescent-state logic, which provides good scalability at the price of millisecond-scale latencies on the transition to full-system-idle state. This is not so good for battery-powered systems, which are usually small enough that they don't need to care about scalability, but which do care deeply about energy efficiency. Small systems therefore drive the state machine directly out of the idle-entry code. The number of CPUs in a "small" system is defined by a new NO_HZ_FULL_SYSIDLE_SMALL Kconfig parameter, which defaults to 8. Note that this is a build-time definition. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> [ paulmck: Use true and false for boolean constants per Lai Jiangshan. ] Reviewed-by: Josh Triplett <josh@joshtriplett.org> [ paulmck: Simplify logic and provide better comments for memory barriers, based on review comments and questions by Lai Jiangshan. ]
* rcu: Eliminate unused APIs intended for adaptive ticksPaul E. McKenney2013-08-181-4/+0
| | | | | | | | | | | The rcu_user_enter_after_irq() and rcu_user_exit_after_irq() functions were intended for use by adaptive ticks, but changes in implementation have rendered them unnecessary. This commit therefore removes them. Reported-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* rcu: Add const annotation to char * for RCU tracepoints and functionsSteven Rostedt (Red Hat)2013-07-291-2/+2
| | | | | | | | | | | | | | | | | All the RCU tracepoints and functions that reference char pointers do so with just 'char *' even though they do not modify the contents of the string itself. This will cause warnings if a const char * is used in one of these functions. The RCU tracepoints store the pointer to the string to refer back to them when the trace output is displayed. As this can be minutes, hours or even days later, those strings had better be constant. This change also opens the door to allow the RCU tracepoint strings and their addresses to be exported so that userspace tracing tools can translate the contents of the pointers of the RCU tracepoints. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* rcu: Shrink TINY_RCU by moving exit_rcu()Paul E. McKenney2013-06-101-2/+0
| | | | | | | | | | | | 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 <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* rcu: Simplify RCU_TINY RCU callback invocationPaul E. McKenney2013-06-101-0/+1
| | | | | | | | | | 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 <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* rcu: Remove TINY_PREEMPT_RCUPaul E. McKenney2013-06-101-1/+1
| | | | | | | | | | | | | | | | 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@linux.vnet.ibm.com> [ paulmck: Updated to eliminate #else in rcutiny.h as suggested by Josh ] Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* rcu: Add _notrace variation of rcu_dereference_raw() and ↵Steven Rostedt2013-05-281-0/+9
| | | | | | | | | | | | | | | | | | hlist_for_each_entry_rcu() 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 <paulmck@linux.vnet.ibm.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
* Merge commit '8700c95adb03' into timers/nohzFrederic Weisbecker2013-05-021-0/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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.h Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
| * rcu: Make RCU_FAST_NO_HZ take advantage of numbered callbacksPaul E. McKenney2013-03-261-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | 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 <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* | nohz: Ensure full dynticks CPUs are RCU nocbsFrederic Weisbecker2013-04-191-0/+7
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <rostedt@goodmis.org> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
*-. Merge branches 'doctorture.2013.01.29a', 'fixes.2013.01.26a', ↵Paul E. McKenney2013-01-281-1/+1
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 'tagcb.2013.01.24a' 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.
| * | rcu: Remove obsolete Kconfig option from commentPaul E. McKenney2013-01-261-1/+1
| |/ | | | | | | Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* / rcu: Reduce rcutorture tracingPaul E. McKenney2013-01-081-3/+10
|/ | | | | | | | | | | | | | | | 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 <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> [ paulmck: Add fix to build problem located by Randy Dunlap based on diagnosis by Steven Rostedt. ]
* context_tracking: New context tracking susbsystemFrederic Weisbecker2012-11-301-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Gilad Ben-Yossef <gilad@benyossef.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> [ paulmck: fix whitespace error and email address. ] Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
*-. Merge branches 'urgent.2012.10.27a', 'doc.2012.11.16a', 'fixes.2012.11.13a', ↵Paul E. McKenney2012-11-161-0/+27
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 'srcu.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.
| | * rcu: Remove rcu_switch()Frederic Weisbecker2012-10-231-0/+2
| |/ |/| | | | | | | | | | | | | | | | | | | | | 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 <fweisbec@gmail.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Richard Weinberger <richard@nod.at> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| * rcu: Clarify memory-ordering properties of grace-period primitivesPaul E. McKenney2012-11-131-0/+25
|/ | | | | | | | | | | | 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 <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com>
* rcu: Switch task's syscall hooks on context switchFrederic Weisbecker2012-09-261-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <fweisbec@gmail.com> Cc: Alessio Igor Bogani <abogani@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Avi Kivity <avi@redhat.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Kevin Hilman <khilman@ti.com> Cc: Max Krasnyansky <maxk@qualcomm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephen Hemminger <shemminger@vyatta.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Sven-Thorsten Dietrich <thebigcorporation@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* rcu: Settle config for userspace extended quiescent stateFrederic Weisbecker2012-09-261-0/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <fweisbec@gmail.com> Cc: Alessio Igor Bogani <abogani@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Avi Kivity <avi@redhat.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Kevin Hilman <khilman@ti.com> Cc: Max Krasnyansky <maxk@qualcomm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephen Hemminger <shemminger@vyatta.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Sven-Thorsten Dietrich <thebigcorporation@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* rcu: New rcu_user_enter_after_irq() and rcu_user_exit_after_irq() APIsFrederic Weisbecker2012-09-261-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <fweisbec@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* rcu: New rcu_user_enter() and rcu_user_exit() APIsFrederic Weisbecker2012-09-261-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <fweisbec@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Alessio Igor Bogani <abogani@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Avi Kivity <avi@redhat.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@ti.com> Cc: Max Krasnyansky <maxk@qualcomm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephen Hemminger <shemminger@vyatta.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Sven-Thorsten Dietrich <thebigcorporation@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
* rcu: Permit RCU_NONIDLE() to be used from interrupt contextPaul E. McKenney2012-09-231-4/+2
| | | | | | | | | | | | | | | | | 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 <rostedt@goodmis.org> Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Fix broken strings in RCU's source code.Paul E. McKenney2012-07-061-2/+1
| | | | | | | | | | | 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 <josh@joshtriplett.org> Suggested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
*-. Merge branches 'bigrtm.2012.07.04a', 'doctorture.2012.07.02a', ↵Paul E. McKenney2012-07-061-31/+19
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 'fixes.2012.07.06a' 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.
| | * rcu: Fix qlen_lazy breakagePaul E. McKenney2012-07-021-1/+1
| |/ |/| | | | | | | | | | | | | | | | | | | | | 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 <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| * rcu: Make __call_rcu() handle invocation from idlePaul E. McKenney2012-07-021-9/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <fweisbec@gmail.com> Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| * rcu: Remove function versions of __kfree_rcu and __is_kfree_rcu_offsetPaul E. McKenney2012-07-021-18/+0
| | | | | | | | | | | | | | | | | | | | 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 <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| * rcu: Consolidate tree/tiny __rcu_read_{,un}lock() implementationsPaul E. McKenney2012-07-021-0/+1
| | | | | | | | | | | | | | | | | | | | 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 <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| * rcu: Remove return value from rcu_assign_pointer()Paul E. McKenney2012-07-021-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <mathieu.desnoyers@efficios.com> Reported-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
| * rcu: Remove return value from RCU_INIT_POINTER()Paul E. McKenney2012-07-021-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Acked-by: David Howells <dhowells@redhat.com>
generated by cgit v1.2.3 (git 2.25.1) at 2024-08-31 14:01:51 +0000