Messages in this thread | | | Subject | Re: [rfc][patch] futex: restartable futex_wait? | From | Thomas Gleixner <> | Date | Fri, 09 Mar 2007 00:02:31 +0100 |
| |
On Thu, 2007-03-08 at 18:29 +0100, Ingo Molnar wrote: > * Nick Piggin <npiggin@suse.de> wrote: > > > Hi Ingo, > > > > I'm seeing an LTP test fail for ltp test sigaction_16_24. Basically, > > it tests whether the SA_RESTART flag works for the sem_wait operation.
Not sure, whether the testcase is correct or not. See below
> > I see sem_wait is implemented with futex_wait, so I wonder whether we > > can make it restartable? Am I going about it the right way? (Seems to > > fix the testcase here). > > i think that's quite right. I'm wondering why this never came up before? > But your fix is not complete i think: > > > + restart->arg2 = time; > > + return -ERESTART_RESTARTBLOCK; > > + } > > 'time' here is relative, so the restarted syscall will do a /full/ wait > again. > > maybe we should rather convert futex timed-waits to hrtimers? Thomas?
The problem is that the original API is based on relative time and therefor can not be changed.
sem_wait returns -EINTR to the application when it is interrupted, while pthread_mutex_lock does not.
http://www.opengroup.org/onlinepubs/009695399/functions/sem_wait.html
http://www.opengroup.org/onlinepubs/009695399/functions/pthread_mutex_lock.html
We need to create a seperate op for the futex - just like the pi_futex and use absolute time there too.
tglx
- 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/
| |