Nick Piggin 15d0d3b337 generic IPI: simplify barriers and locking ... Simplify the barriers in generic remote function call interrupt code. Firstly, just unconditionally take the lock and check the list in the generic_call_function_single_interrupt IPI handler. As we've just taken an IPI here, the chances are fairly high that there will be work on the list for us, so do the locking unconditionally. This removes the tricky lockless list_empty check and dubious barriers. The change looks bigger than it is because it is just removing an outer loop. Secondly, clarify architecture specific IPI locking rules. Generic code has no tools to impose any sane ordering on IPIs if they go outside normal cache coherency, ergo the arch code must make them appear to obey cache coherency as a "memory operation" to initiate an IPI, and a "memory operation" to receive one. This way at least they can be reasoned about in generic code, and smp_mb used to provide ordering. The combination of these two changes means that explict barriers can be taken out of queue handling for the single case -- shared data is explicitly locked, and ipi ordering must conform to that, so no barriers needed. An extra barrier is needed in the many handler, so as to ensure we load the list element after the IPI is received. Does any architecture actually *need* these barriers? For the initiator I could see it, but for the handler I would be surprised. So the other thing we could do for simplicity is just to require that, rather than just matching with cache coherency, we just require a full barrier before generating an IPI, and after receiving an IPI. In which case, the smp_mb()s can go away. But just for now, we'll be on the safe side and use the barriers (they're in the slow case anyway). Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: linux-arch@vger.kernel.org Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jens Axboe <jens.axboe@oracle.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>		2009-02-25 12:27:08 +01:00
..
irq	Merge branch 'core/xen' into x86/urgent	2009-02-04 14:54:56 +01:00
power	PM: Split up sysdev_[suspend|resume] from device_power_[down|up]	2009-02-22 10:33:44 -08:00
time	hrtimers: allow the hot-unplugging of all cpus	2009-01-30 22:35:29 +01:00
trace	tracing: limit the number of loops the ring buffer self test can make	2009-02-18 22:50:01 -05:00
.gitignore
acct.c	[CVE-2009-0029] System call wrappers part 04	2009-01-14 14:15:19 +01:00
async.c	async: use list_move_tail	2009-02-08 10:00:26 -08:00
audit.c	[PATCH] fix broken timestamps in AVC generated by kernel threads	2008-12-09 02:27:41 -05:00
audit.h	fixing audit rule ordering mess, part 1	2009-01-04 15:14:41 -05:00
audit_tree.c	audit: validate comparison operations, store them in sane form	2009-01-04 15:14:42 -05:00
auditfilter.c	audit: validate comparison operations, store them in sane form	2009-01-04 15:14:42 -05:00
auditsc.c	make sure that filterkey of task,always rules is reported	2009-01-04 15:14:42 -05:00
backtracetest.c
bounds.c
capability.c	[CVE-2009-0029] System call wrappers part 04	2009-01-14 14:15:19 +01:00
cgroup.c	cgroups: fix possible use after free	2009-02-18 15:37:54 -08:00
cgroup_debug.c
cgroup_freezer.c	freezer_cg: disable writing freezer.state of root cgroup	2008-11-12 17:17:16 -08:00
compat.c	Allow times and time system calls to return small negative values	2009-01-06 15:59:13 -08:00
configs.c
cpu.c	stop_machine/cpu hotplug: fix disable_nonboot_cpus	2009-01-07 11:36:14 -08:00
cpuset.c	cpuset: fix possible deadlock in async_rebuild_sched_domains	2009-01-19 02:44:00 +01:00
cred-internals.h	CRED: Inaugurate COW credentials	2008-11-14 10:39:23 +11:00
cred.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6	2009-01-09 13:59:25 -08:00
delayacct.c	schedstat: consolidate per-task cpu runtime stats	2008-12-18 13:54:01 +01:00
dma-coherent.c	dma-coherent: Restore dma_alloc_from_coherent() large alloc fall back policy.	2009-01-21 18:51:53 +09:00
dma.c
exec_domain.c	[CVE-2009-0029] System call wrappers part 04	2009-01-14 14:15:19 +01:00
exit.c	signal: re-add dead task accumulation stats.	2009-02-05 13:04:33 +01:00
extable.c	Merge branch 'core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2008-12-30 16:10:19 -08:00
fork.c	Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-02-11 08:24:32 -08:00
freezer.c	freezer_cg: use thaw_process() in unfreeze_cgroup()	2008-10-30 11:38:45 -07:00
futex.c	futex: fix reference leak	2009-02-11 18:24:08 +01:00
futex_compat.c	CRED: Use RCU to access another task's creds and to release a task's own creds	2008-11-14 10:39:19 +11:00
hrtimer.c	hrtimer: prevent negative expiry value after clock_was_set()	2009-01-30 22:35:34 +01:00
itimer.c	timers: split process wide cpu clocks/timers	2009-02-05 13:04:33 +01:00
kallsyms.c	Revert "kbuild: strip generated symbols from *.ko"	2009-01-14 21:38:20 +01:00
Kconfig.freezer
Kconfig.hz
Kconfig.preempt	rcu: provide RCU options on non-preempt architectures too	2008-12-25 09:31:28 +01:00
kexec.c	PM: Split up sysdev_[suspend|resume] from device_power_[down|up]	2009-02-22 10:33:44 -08:00
kfifo.c
kgdb.c
kmod.c	kmod: fix varargs kernel-doc	2009-01-06 15:59:27 -08:00
kprobes.c	kprobes: check CONFIG_FREEZER instead of CONFIG_PM	2009-01-16 14:32:17 -05:00
ksysfs.c	kernel/ksysfs.c:fix dependence on CONFIG_NET	2009-01-06 10:44:31 -08:00
kthread.c	tracepoints: add DECLARE_TRACE() and DEFINE_TRACE()	2008-11-16 09:01:36 +01:00
latencytop.c	KSYM_SYMBOL_LEN fixes	2008-12-10 08:01:54 -08:00
lockdep.c	Merge branch 'core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2008-12-30 16:10:19 -08:00
lockdep_internals.h
lockdep_proc.c
Makefile	PM: fix build for CONFIG_PM unset	2009-02-21 14:17:17 -08:00
marker.c	markers/tracpoints: fix non-modular build	2008-11-16 09:52:03 +01:00
module.c	modules: Use a better scheme for refcounting	2009-02-02 19:17:55 -08:00
mutex-debug.c
mutex-debug.h
mutex.c	mutex: __used is needed for function referenced only from inline asm	2008-11-24 10:00:28 +01:00
mutex.h
notifier.c	Merge commit 'v2.6.28-rc6' into core/debug	2008-11-26 08:22:50 +01:00
ns_cgroup.c	ns_cgroup: remove unused spinlock	2009-01-08 08:31:02 -08:00
nsproxy.c	User namespaces: set of cleanups (v2)	2008-11-24 18:57:41 -05:00
panic.c	oops: increment the oops UUID every time we oops	2009-01-06 15:59:12 -08:00
params.c
pid.c	pid: generalize task_active_pid_ns	2009-01-08 08:31:12 -08:00
pid_namespace.c
pm_qos_params.c
posix-cpu-timers.c	timers: more consistently use clock vs timer	2009-02-13 13:04:05 +01:00
posix-timers.c	[CVE-2009-0029] System call wrappers part 05	2009-01-14 14:15:20 +01:00
printk.c	PM: Fix suspend_console and resume_console to use only one semaphore	2009-02-21 14:17:18 -08:00
profile.c	profiling: fix broken profiling regression	2009-02-10 00:50:37 +01:00
ptrace.c	[CVE-2009-0029] System call wrappers part 27	2009-01-14 14:15:29 +01:00
rcuclassic.c	rcu: add __cpuinit to rcu_init_percpu_data()	2009-01-14 11:26:40 +01:00
rcupdate.c	rcu: eliminate synchronize_rcu_xxx macro	2009-01-05 10:18:08 +01:00
rcupreempt.c	rcu: eliminate synchronize_rcu_xxx macro	2009-01-05 10:18:08 +01:00
rcupreempt_trace.c	"Tree RCU": scalable classic RCU implementation	2008-12-18 21:56:04 +01:00
rcutorture.c	rcu: fix bug in rcutorture system-shutdown code	2009-01-07 23:36:25 +01:00
rcutree.c	rcu: add __cpuinit to rcu_init_percpu_data()	2009-01-14 11:26:40 +01:00
rcutree_trace.c	"Tree RCU": scalable classic RCU implementation	2008-12-18 21:56:04 +01:00
relay.c	relay: fix lock imbalance in relay_late_setup_files	2009-01-18 20:29:35 +01:00
res_counter.c	memcg: memory cgroup resource counters for hierarchy	2009-01-08 08:31:05 -08:00
resource.c	resources: fix parameter name and kernel-doc	2009-01-15 16:39:38 -08:00
rtmutex-debug.c
rtmutex-debug.h
rtmutex-tester.c
rtmutex.c
rtmutex.h
rtmutex_common.h
rwsem.c
sched.c	sched: cpu hotplug fix	2009-02-12 11:57:36 +01:00
sched_clock.c	sched_clock: prevent scd->clock from moving backwards, take #2	2008-12-31 09:53:21 +01:00
sched_cpupri.c	sched: fix section mismatch	2009-01-06 11:07:15 +01:00
sched_cpupri.h	sched: convert struct cpupri_vec cpumask_var_t.	2008-11-24 17:52:22 +01:00
sched_debug.c	sched: partly revert "sched debug: remove NULL checking in print_cfs_rt_rq()"	2009-01-11 02:40:32 +01:00
sched_fair.c	sched: revert recent sync wakeup changes	2009-02-11 14:43:35 +01:00
sched_features.h	sched: backward looking buddy	2008-11-05 10:30:14 +01:00
sched_idletask.c
sched_rt.c	sched_rt: don't use first_cpu on cpumask created with cpumask_and	2009-02-01 10:49:52 +01:00
sched_stats.h	timers: split process wide cpu clocks/timers	2009-02-05 13:04:33 +01:00
seccomp.c
semaphore.c
signal.c	signal: re-add dead task accumulation stats.	2009-02-05 13:04:33 +01:00
smp.c	generic IPI: simplify barriers and locking	2009-02-25 12:27:08 +01:00
softirq.c	Merge branch 'cpus4096-for-linus-3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip	2009-01-03 12:04:39 -08:00
softlockup.c	softlock: fix false panic which can occur if softlockup_thresh is reduced	2009-01-14 11:48:07 +01:00
spinlock.c
srcu.c
stacktrace.c	stacktrace: provide save_stack_trace_tsk() weak alias	2008-12-25 11:44:43 +01:00
stop_machine.c	stop_machine: introduce stop_machine_create/destroy.	2009-01-05 08:40:14 +10:30
sys.c	revert "rlimit: permit setting RLIMIT_NOFILE to RLIM_INFINITY"	2009-02-05 12:56:47 -08:00
sys_ni.c	[CVE-2009-0029] Make sys_syslog a conditional system call	2009-01-14 14:15:16 +01:00
sysctl.c	mm: fix dirty_bytes/dirty_background_bytes sysctls on 64bit arches	2009-02-11 14:25:35 -08:00
sysctl_check.c	[XFS] remove restricted chown parameter from xfs linux	2008-10-30 18:30:09 +11:00
taskstats.c	cpumask: convert rest of files in kernel/	2009-01-01 10:12:28 +10:30
test_kprobes.c	kprobes: add tests for register_kprobes	2009-01-06 15:59:20 -08:00
time.c	[CVE-2009-0029] System call wrappers part 01	2009-01-14 14:15:18 +01:00
timeconst.pl
timer.c	[CVE-2009-0029] System call wrappers part 27	2009-01-14 14:15:29 +01:00
tracepoint.c	markers/tracpoints: fix non-modular build	2008-11-16 09:52:03 +01:00
tsacct.c	mm: introduce get_mm_hiwater_xxx(), fix taskstats->hiwater_xxx accounting	2009-01-06 15:59:09 -08:00
uid16.c	[CVE-2009-0029] System call wrappers part 19	2009-01-14 14:15:26 +01:00
up.c	smp_call_function_single(): be slightly less stupid, fix #2	2009-01-12 16:04:37 +01:00
user.c	User namespaces: Only put the userns when we unhash the uid	2009-02-13 08:07:40 -08:00
user_namespace.c	User namespaces: set of cleanups (v2)	2008-11-24 18:57:41 -05:00
utsname.c
utsname_sysctl.c
wait.c	wait: prevent exclusive waiter starvation	2009-02-05 12:56:48 -08:00
workqueue.c	work_on_cpu: Use our own workqueue.	2009-01-19 22:36:07 +01:00