diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2018-01-22 11:39:47 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-03-03 16:44:24 +0100 |
| commit | e68489bc827dbb9ae28f3e082b147d303599151b (patch) | |
| tree | 3de7191f2f79f188b65a8dd462ebaa9e26d5383e /kernel | |
| parent | 66c48b3a9a6a18047b7815fe0adccc1892033081 (diff) | |
futex: Fix OWNER_DEAD fixup
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>
Reviewed-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/futex.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index 199e63c5b612..70ad21bbb1d5 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -2248,10 +2248,6 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q, oldowner = pi_state->owner; - /* Owner died? */ - if (!pi_state->owner) - newtid |= FUTEX_OWNER_DIED; - /* * We are here because either: * @@ -2309,6 +2305,9 @@ retry: } 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; |