diff options
author | Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> | 2009-09-22 16:43:39 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-23 07:39:28 -0700 |
commit | 54fdade1c3332391948ec43530c02c4794a38172 (patch) | |
tree | a44cfa6888bbe702321e4d4737786e5292d72eaa /include/linux/cpumask.h | |
parent | 5c725138437837291db5c25f4a076ee852e806e3 (diff) |
generic-ipi: make struct call_function_data lockless
This patch can remove spinlock from struct call_function_data, the
reasons are below:
1: add a new interface for cpumask named cpumask_test_and_clear_cpu(),
it can atomically test and clear specific cpu, we can use it instead
of cpumask_test_cpu() and cpumask_clear_cpu() and no need data->lock
to protect those in generic_smp_call_function_interrupt().
2: in smp_call_function_many(), after csd_lock() return, the current's
cfd_data is deleted from call_function list, so it not have race
between other cpus, then cfs_data is only used in
smp_call_function_many() that must disable preemption and not from
a hardware interrupthandler or from a bottom half handler to call,
only the correspond cpu can use it, so it not have race in current
cpu, no need cfs_data->lock to protect it.
3: after 1 and 2, cfs_data->lock is only use to protect cfs_data->refs in
generic_smp_call_function_interrupt(), so we can define cfs_data->refs
to atomic_t, and no need cfs_data->lock any more.
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
[akpm@linux-foundation.org: use atomic_dec_return()]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/cpumask.h')
-rw-r--r-- | include/linux/cpumask.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index 796df12091b..9b1d458aac6 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -715,6 +715,18 @@ static inline int cpumask_test_and_set_cpu(int cpu, struct cpumask *cpumask) } /** + * cpumask_test_and_clear_cpu - atomically test and clear a cpu in a cpumask + * @cpu: cpu number (< nr_cpu_ids) + * @cpumask: the cpumask pointer + * + * test_and_clear_bit wrapper for cpumasks. + */ +static inline int cpumask_test_and_clear_cpu(int cpu, struct cpumask *cpumask) +{ + return test_and_clear_bit(cpumask_check(cpu), cpumask_bits(cpumask)); +} + +/** * cpumask_setall - set all cpus (< nr_cpu_ids) in a cpumask * @dstp: the cpumask pointer */ |