(the email address of Matthew Wilcox looks wrong, changed to [EMAIL PROTECTED])
On 06/29, Oleg Nesterov wrote: > > Steven, unless you have some objections, could you change tasklet_kill() ? > > > +static inline void tasklet_kill(struct tasklet_struct *t) > > { > > - return test_bit(TASKLET_STATE_SCHED, &t->state); > > + flush_workqueue(ktaskletd_wq); > > } > > Just change flush_workqueue(ktaskletd_wq) to cancel_work_sync(t-work). Ugh, tasklet_disable() should be changed as well. > @@ -84,35 +50,35 @@ static inline void tasklet_disable_nosyn > static inline void tasklet_disable(struct tasklet_struct *t) > { > tasklet_disable_nosync(t); > - tasklet_unlock_wait(t); > - smp_mb(); > -} > - > -static inline void tasklet_enable(struct tasklet_struct *t) > -{ > - smp_mb__before_atomic_dec(); > - atomic_dec(&t->count); > + flush_workqueue(ktaskletd_wq); > + /* flush_workqueue should provide us a barrier */ > } Suppose we have the tasklets T1 and T2, both are scheduled on the same CPU. T1 takes some spinlock LOCK. Currently it is possible to do spin_lock(LOCK); disable_tasklet(T2); With this patch, the above code hangs. The most simple fix is to use wait_on_work(t->work) instead of flush_workqueue(). Currently it is static, but we can export it. This change will speedup tasklet_disable), btw. A better fix imho is to use cancel_work_sync() again, but this needs some complications to preserve TASKLET_STATE_PENDING. This in turn means that cancel_work_sync() should return "int", but not "void". This change makes sense regardless, I'll try to make a patch on Sunday. Oleg. - 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/