Messages in this thread | | | Subject | Re: [PATCH 4.9.y 1/1] futex: Fix OWNER_DEAD fixup | From | "Zhengyejian (Zetta)" <> | Date | Thu, 25 Feb 2021 14:29:34 +0800 |
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On 2021/2/24 19:19, Lee Jones wrote: > On Tue, 23 Feb 2021, Zheng Yejian wrote: > >> From: Peter Zijlstra <peterz@infradead.org> >> >> commit a97cb0e7b3f4c6297fd857055ae8e895f402f501 upstream. >> >> Both Geert and DaveJ reported that the recent futex commit: >> >> c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex") >> >> introduced a problem with setting OWNER_DEAD. We set the bit on an >> uninitialized variable and then entirely optimize it away as a >> dead-store. >> >> Move the setting of the bit to where it is more useful. >> >> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org> >> Reported-by: Dave Jones <davej@codemonkey.org.uk> >> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> >> Cc: Andrew Morton <akpm@linux-foundation.org> >> Cc: Linus Torvalds <torvalds@linux-foundation.org> >> Cc: Paul E. McKenney <paulmck@us.ibm.com> >> Cc: Peter Zijlstra <peterz@infradead.org> >> Cc: Thomas Gleixner <tglx@linutronix.de> >> Fixes: c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex") >> Link: http://lkml.kernel.org/r/20180122103947.GD2228@hirez.programming.kicks-ass.net >> Signed-off-by: Ingo Molnar <mingo@kernel.org> >> Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com> > > Why have you dropped my Reviewed-by? > Really sorry. I thought that a changed patchset needs another review. Then I do need to append your Reviewed-by and send a "V2" patchset, Do I?
>> --- >> kernel/futex.c | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/kernel/futex.c b/kernel/futex.c >> index b65dbb5d60bb..604d1cb9839d 100644 >> --- a/kernel/futex.c >> +++ b/kernel/futex.c >> @@ -2424,9 +2424,6 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q, >> int err = 0; >> >> oldowner = pi_state->owner; >> - /* Owner died? */ >> - if (!pi_state->owner) >> - newtid |= FUTEX_OWNER_DIED; >> >> /* >> * We are here because either: >> @@ -2484,6 +2481,9 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q, >> } >> >> newtid = task_pid_vnr(newowner) | FUTEX_WAITERS; >> + /* Owner died? */ >> + if (!pi_state->owner) >> + newtid |= FUTEX_OWNER_DIED; >> >> if (get_futex_value_locked(&uval, uaddr)) >> goto handle_fault; >
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