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 Signed-off-by: Christoph Lameter --- kernel/irq_work.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) Index: linux-2.6/kernel/irq_work.c =================================================================== --- linux-2.6.orig/kernel/irq_work.c 2010-12-07 10:24:30.000000000 -0600 +++ linux-2.6/kernel/irq_work.c 2010-12-07 10:26:45.000000000 -0600 @@ -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; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/