Messages in this thread Patch in this message | | | Subject | Re: [PATCH V2] futex: set FLAGS_HAS_TIMEOUT during demux for FUTEX_WAIT | From | Eric Dumazet <> | Date | Thu, 14 Apr 2011 20:56:31 +0200 |
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Le jeudi 14 avril 2011 à 11:45 -0700, Darren Hart a écrit : > The FLAGS_HAS_TIMEOUT flag was not getting set, causing the restart_block to > restart futex_wait() without a timeout after a signal. > > Commit b41277dc7a18ee332d in 2.6.38 introduced the regression by accidentally > removing the the FLAGS_HAS_TIMEOUT assignment from futex_wait() during the setup > of the restart block. It makes more sense to set the flag earlier during > do_futex() where the other flags are set, although futex_wait is the only user > of FLAGS_HAS_TIMEOUT as it is the only op using a relative timeout (an > unfortunately preexisting condition). > > Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=32922 > > V2: Added references to commit message. > > Signed-off-by: Darren Hart <dvhart@linux.intel.com> > Reported-by: Tim Smith <tsmith201104@yahoo.com> > Reported-by: Torsten Hilbrich <torsten.hilbrich@secunet.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Ingo Molnar <mingo@elte.hu> > CC: Eric Dumazet <eric.dumazet@gmail.com> > CC: John Kacur <jkacur@redhat.com> > --- > kernel/futex.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/kernel/futex.c b/kernel/futex.c > index bda4157..6eac6b6 100644 > --- a/kernel/futex.c > +++ b/kernel/futex.c > @@ -2589,6 +2589,9 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout, > return -ENOSYS; > } > > + if (timeout) > + flags |= FLAGS_HAS_TIMEOUT; > + > switch (cmd) { > case FUTEX_WAIT: > val3 = FUTEX_BITSET_MATCH_ANY;
I dont agree with your fix. You add yet another test in futex fastpath.
Prior commit b41277dc7a18ee332d, this was done only in case of restart.
Could we instead use
diff --git a/kernel/futex.c b/kernel/futex.c index dfb924f..fe28dc2 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1886,7 +1886,7 @@ retry: restart->futex.val = val; restart->futex.time = abs_time->tv64; restart->futex.bitset = bitset; - restart->futex.flags = flags; + restart->futex.flags = flags | FLAGS_HAS_TIMEOUT; ret = -ERESTART_RESTARTBLOCK;
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