62 lines
2.0 KiB
Diff
62 lines
2.0 KiB
Diff
From ad3a4959139317221f6e72f3d69da320ccc218be Mon Sep 17 00:00:00 2001
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From: Peter Zijlstra <peterz@infradead.org>
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Date: Wed, 6 Jun 2018 15:31:29 +0200
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Subject: [PATCH 346/365] futex: Fix OWNER_DEAD fixup
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[ Upstream commit a97cb0e7b3f4c6297fd857055ae8e895f402f501 ]
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Both Geert and DaveJ reported that the recent futex commit:
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c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
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introduced a problem with setting OWNER_DEAD. We set the bit on an
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uninitialized variable and then entirely optimize it away as a
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dead-store.
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Move the setting of the bit to where it is more useful.
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Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
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Reported-by: Dave Jones <davej@codemonkey.org.uk>
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Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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Cc: Andrew Morton <akpm@linux-foundation.org>
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Cc: Linus Torvalds <torvalds@linux-foundation.org>
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Cc: Paul E. McKenney <paulmck@us.ibm.com>
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Cc: Peter Zijlstra <peterz@infradead.org>
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Cc: Thomas Gleixner <tglx@linutronix.de>
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Fixes: c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
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Link: http://lkml.kernel.org/r/20180122103947.GD2228@hirez.programming.kicks-ass.net
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Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Signed-off-by: Julia Cartwright <julia@ni.com>
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---
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kernel/futex.c | 6 +++---
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1 file changed, 3 insertions(+), 3 deletions(-)
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diff --git a/kernel/futex.c b/kernel/futex.c
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index 498a2980e0d7..0279bf7c69b4 100644
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--- a/kernel/futex.c
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+++ b/kernel/futex.c
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@@ -2326,9 +2326,6 @@ 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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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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* We are here because either:
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@@ -2389,6 +2386,9 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
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}
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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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goto handle_fault;
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--
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2.28.0
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