futex: Fix OWNER_DEAD fixup
Both Geert and DaveJ reported that the recent futex commit:c1e2f0eaf0
("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:c1e2f0eaf0
("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>
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1f07476ec1
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a97cb0e7b3
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@ -2311,9 +2311,6 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
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raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
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raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
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oldowner = pi_state->owner;
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oldowner = pi_state->owner;
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/* Owner died? */
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if (!pi_state->owner)
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newtid |= FUTEX_OWNER_DIED;
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/*
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/*
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* We are here because either:
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* We are here because either:
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@ -2374,6 +2371,9 @@ retry:
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}
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}
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newtid = task_pid_vnr(newowner) | FUTEX_WAITERS;
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newtid = task_pid_vnr(newowner) | FUTEX_WAITERS;
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/* Owner died? */
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if (!pi_state->owner)
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newtid |= FUTEX_OWNER_DIED;
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if (get_futex_value_locked(&uval, uaddr))
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if (get_futex_value_locked(&uval, uaddr))
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goto handle_fault;
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goto handle_fault;
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