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 16:50:45 +0800 |
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On 2021/2/25 16:09, Lee Jones wrote: > On Thu, 25 Feb 2021, Zhengyejian (Zetta) wrote: > >> >> >> 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? > > No need. I won't hold up merging just for that. > > Just bear in mind that you should apply and carry forward *-by tags > unless there have been significant/functional changes. > > Reviewed-by: Lee Jones <lee.jones@linaro.org> >
I get it, thanks.
>>>> --- >>>> 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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