On 06/10/2013 08:25 PM, Paul E. McKenney wrote: > 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 <[email protected]> >> > --- >> > 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?
Oh, it seems not safe, at least it is not the original author's willing. It is my fault, and also sorry for replying late. Thanks. -- Chen Gang Asianux Corporation -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
