On Wed, 2012-10-31 at 23:02 +0900, anish kumar wrote:
> From: anish kumar <anish198519851...@gmail.com>
>
> As no one is using the return value of irq_work_queue function
> it is better to just make it void.
>
> This patch is just a way to understand if there is some future
> plan to use it but in any case please let me know the reason.
> ---
> kernel/irq_work.c | 21 ++++++++++-----------
> 1 files changed, 10 insertions(+), 11 deletions(-)
>
> diff --git a/kernel/irq_work.c b/kernel/irq_work.c
> index 1588e3b..4a9a44c 100644
> --- a/kernel/irq_work.c
> +++ b/kernel/irq_work.c
> @@ -32,21 +32,21 @@ static DEFINE_PER_CPU(struct llist_head, irq_work_list);
> /*
> * Claim the entry so that no one else will poke at it.
> */
> -static bool irq_work_claim(struct irq_work *work)
> +static void irq_work_claim(struct irq_work *work)
> {
> unsigned long flags, nflags;
>
> for (;;) {
> flags = work->flags;
> if (flags & IRQ_WORK_PENDING)
> - return false;
> + return;
> nflags = flags | IRQ_WORK_FLAGS;
> if (cmpxchg(&work->flags, flags, nflags) == flags)
> break;
> cpu_relax();
> }
>
> - return true;
> + return;
> }
>
> void __weak arch_irq_work_raise(void)
> @@ -79,15 +79,14 @@ static void __irq_work_queue(struct irq_work *work)
> *
> * Can be re-enqueued while the callback is still in progress.
> */
> -bool irq_work_queue(struct irq_work *work)
> +void irq_work_queue(struct irq_work *work)
> {
> - if (!irq_work_claim(work)) {
> - /*
> - * Already enqueued, can't do!
> - */
> - return false;
> - }
> -
> + /*
> + * This function either will claim the entry to queue
> + * the work or if the work is already queued and is in
> + * pending state then it will simply return.
> + */
> + irq_work_claim(work)
Um, no.
If the state was already pending, we will corrupt the llist node of the
work if we call irq_work_queue(). You must check the return value of
irq_work_claim() and return if it fails. You can not call
__irq_work_queue() if irq_work_claim() does not succeed.
The return value of irq_work_queue() can be ignored, but not
irq_work_claim().
-- Steve
> __irq_work_queue(work);
> return true;
> }
--
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