On Sun, Jun 09, 2013 at 08:30:19PM +0800, Chen Gang wrote:
>
> After finish the internal 'while', need not test TASKLET_STATE_SCHED
> again, so looping back to outside 'while' is only for set_bit().
>
> When use 'if' and set_bit() instead of 'while', it will save at least
> one running conditional instruction, and also will be clearer for readers
> (although the binary size will be a little bigger).
>
> The related patch is "1da177e Linux-2.6.12-rc2"
>
>
> Signed-off-by: Chen Gang <gang.c...@asianux.com>
> ---
> kernel/softirq.c | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/softirq.c b/kernel/softirq.c
> index a5f8836..52da25f 100644
> --- a/kernel/softirq.c
> +++ b/kernel/softirq.c
> @@ -540,10 +540,11 @@ void tasklet_kill(struct tasklet_struct *t)
> if (in_interrupt())
> printk("Attempt to kill tasklet from interrupt\n");
>
> - while (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) {
> + if (test_and_set_bit(TASKLET_STATE_SCHED, &t->state)) {
> do {
> yield();
> } while (test_bit(TASKLET_STATE_SCHED, &t->state));
> + set_bit(TASKLET_STATE_SCHED, &t->state);
This replaces an atomic test-and-set with two operations, a test and
a set. Is this safe?
Thanx, Paul
> }
> tasklet_unlock_wait(t);
> clear_bit(TASKLET_STATE_SCHED, &t->state);
> --
> 1.7.7.6
>
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