diff options
author | Christoph Lameter <cl@linux.com> | 2010-12-14 19:28:45 +0300 |
---|---|---|
committer | Tejun Heo <tj@kernel.org> | 2010-12-18 17:54:48 +0300 |
commit | 20b876918c065818b3574a426d418f68b4f8ad19 (patch) | |
tree | 1e31b61ca0c28f528321ff13ed6315475dbf6992 /kernel/irq_work.c | |
parent | 05c2d088d0eb904e50460b04d77324c26cef4637 (diff) | |
download | linux-20b876918c065818b3574a426d418f68b4f8ad19.tar.xz |
irq_work: Use per cpu atomics instead of regular atomics
The irq work queue is a per cpu object and it is sufficient for
synchronization if per cpu atomics are used. Doing so simplifies
the code and reduces the overhead of the code.
Before:
christoph@linux-2.6$ size kernel/irq_work.o
text data bss dec hex filename
451 8 1 460 1cc kernel/irq_work.o
After:
christoph@linux-2.6$ size kernel/irq_work.o
text data bss dec hex filename
438 8 1 447 1bf kernel/irq_work.o
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Christoph Lameter <cl@linux.com>
Diffstat (limited to 'kernel/irq_work.c')
-rw-r--r-- | kernel/irq_work.c | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/kernel/irq_work.c b/kernel/irq_work.c index 90f881904bb1..c58fa7da8aef 100644 --- a/kernel/irq_work.c +++ b/kernel/irq_work.c @@ -77,21 +77,21 @@ void __weak arch_irq_work_raise(void) */ static void __irq_work_queue(struct irq_work *entry) { - struct irq_work **head, *next; + struct irq_work *next; - head = &get_cpu_var(irq_work_list); + preempt_disable(); do { - next = *head; + next = __this_cpu_read(irq_work_list); /* Can assign non-atomic because we keep the flags set. */ entry->next = next_flags(next, IRQ_WORK_FLAGS); - } while (cmpxchg(head, next, entry) != next); + } while (this_cpu_cmpxchg(irq_work_list, next, entry) != next); /* The list was empty, raise self-interrupt to start processing. */ if (!irq_work_next(entry)) arch_irq_work_raise(); - put_cpu_var(irq_work_list); + preempt_enable(); } /* @@ -120,16 +120,16 @@ EXPORT_SYMBOL_GPL(irq_work_queue); */ void irq_work_run(void) { - struct irq_work *list, **head; + struct irq_work *list; - head = &__get_cpu_var(irq_work_list); - if (*head == NULL) + if (this_cpu_read(irq_work_list) == NULL) return; BUG_ON(!in_irq()); BUG_ON(!irqs_disabled()); - list = xchg(head, NULL); + list = this_cpu_xchg(irq_work_list, NULL); + while (list != NULL) { struct irq_work *entry = list; |