From: Julia Cartwright <julia@ni.com>
To: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>,
Carsten Emde <C.Emde@osadl.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
John Kacur <jkacur@redhat.com>,
Paul Gortmaker <paul.gortmaker@windriver.com>,
Daniel Wagner <daniel.wagner@siemens.com>,
tom.zanussi@linux.intel.com,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
"Paul E . McKenney" <paulmck@us.ibm.com>,
Ingo Molnar <mingo@kernel.org>
Subject: [PATCH RT 04/22] futex: Fix OWNER_DEAD fixup
Date: Mon, 6 Aug 2018 04:17:20 -0500 [thread overview]
Message-ID: <464abec1c5e435a618d3dcd6a05f207e8456d53d.1533540554.git.julia@ni.com> (raw)
In-Reply-To: <cover.1533540554.git.julia@ni.com>
From: Peter Zijlstra <peterz@infradead.org>
4.9.115-rt94-rc1 stable review patch.
If you have any objection to the inclusion of this patch, let me know.
--- 8< --- 8< --- 8< ---
[ Upstream commit a97cb0e7b3f4c6297fd857055ae8e895f402f501 ]
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: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Julia Cartwright <julia@ni.com>
---
kernel/futex.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/futex.c b/kernel/futex.c
index cdd68ba6e3a6..57038131ad3f 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2301,9 +2301,6 @@ static int fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
oldowner = pi_state->owner;
- /* Owner died? */
- if (!pi_state->owner)
- newtid |= FUTEX_OWNER_DIED;
/*
* We are here because either:
@@ -2364,6 +2361,9 @@ 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;
--
2.18.0
next prev parent reply other threads:[~2018-08-06 9:18 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-06 9:17 [PATCH RT 00/22] Linux 4.9.115-rt94-rc1 Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 01/22] futex: Fix pi_state->owner serialization Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 02/22] futex: Fix more put_pi_state() vs. exit_pi_state_list() races Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 03/22] futex: Avoid violating the 10th rule of futex Julia Cartwright
2018-08-06 9:17 ` Julia Cartwright [this message]
2018-08-06 9:17 ` [PATCH RT 05/22] rtmutex: Make rt_mutex_futex_unlock() safe for irq-off callsites Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 06/22] rcu: Do not include rtmutex_common.h unconditionally Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 07/22] rcu: Suppress lockdep false-positive ->boost_mtx complaints Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 08/22] sched, tracing: Fix trace_sched_pi_setprio() for deboosting Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 09/22] crypto: limit more FPU-enabled sections Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 10/22] arm*: disable NEON in kernel mode Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 11/22] mm/slub: close possible memory-leak in kmem_cache_alloc_bulk() Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 12/22] locking: add types.h Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 13/22] net: use task_struct instead of CPU number as the queue owner on -RT Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 14/22] Revert "rt,ntp: Move call to schedule_delayed_work() to helper thread" Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 15/22] Revert "block: blk-mq: Use swait" Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 16/22] block: blk-mq: move blk_queue_usage_counter_release() into process context Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 17/22] alarmtimer: Prevent live lock in alarm_cancel() Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 18/22] posix-timers: move the rcu head out of the union Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 19/22] locallock: provide {get,put}_locked_ptr() variants Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 20/22] squashfs: make use of local lock in multi_cpu decompressor Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 21/22] seqlock: provide the same ordering semantics as mainline Julia Cartwright
2018-08-06 9:17 ` [PATCH RT 22/22] Linux 4.9.115-rt94-rc1 Julia Cartwright
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