From: Peter Zijlstra <peterz@infradead.org>
To: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
manfred@colorfullife.com, dave@stgolabs.net,
paulmck@linux.vnet.ibm.com, will.deacon@arm.com
Cc: boqun.feng@gmail.com, Waiman.Long@hpe.com, tj@kernel.org,
pablo@netfilter.org, kaber@trash.net, davem@davemloft.net,
oleg@redhat.com, netfilter-devel@vger.kernel.org,
sasha.levin@oracle.com, hofrat@osadl.org, peterz@infradead.org
Subject: [PATCH -v3 5/8] locking: Update spin_unlock_wait users
Date: Tue, 31 May 2016 11:41:39 +0200 [thread overview]
Message-ID: <20160531094844.162614942@infradead.org> (raw)
In-Reply-To: 20160531094134.606249808@infradead.org
[-- Attachment #1: peterz-locking-fix-spin_unlock_wait.patch --]
[-- Type: text/plain, Size: 1434 bytes --]
With the modified semantics of spin_unlock_wait() a number of
explicit barriers can be removed. And update the comment for the
do_exit() usecase, as that was somewhat stale/obscure.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
ipc/sem.c | 1 -
kernel/exit.c | 8 ++++++--
kernel/task_work.c | 1 -
3 files changed, 6 insertions(+), 4 deletions(-)
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -282,7 +282,6 @@ static void sem_wait_array(struct sem_ar
sem = sma->sem_base + i;
spin_unlock_wait(&sem->lock);
}
- smp_acquire__after_ctrl_dep();
}
/*
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -776,10 +776,14 @@ void do_exit(long code)
exit_signals(tsk); /* sets PF_EXITING */
/*
- * tsk->flags are checked in the futex code to protect against
- * an exiting task cleaning up the robust pi futexes.
+ * Ensure that all new tsk->pi_lock acquisitions must observe
+ * PF_EXITING. Serializes against futex.c:attach_to_pi_owner().
*/
smp_mb();
+ /*
+ * Ensure that we must observe the pi_state in exit_mm() ->
+ * mm_release() -> exit_pi_state_list().
+ */
raw_spin_unlock_wait(&tsk->pi_lock);
if (unlikely(in_atomic())) {
--- a/kernel/task_work.c
+++ b/kernel/task_work.c
@@ -108,7 +108,6 @@ void task_work_run(void)
* fail, but it can play with *work and other entries.
*/
raw_spin_unlock_wait(&task->pi_lock);
- smp_mb();
do {
next = work->next;
next prev parent reply other threads:[~2016-05-31 9:53 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-31 9:41 [PATCH -v3 0/8] spin_unlock_wait borkage and assorted bits Peter Zijlstra
2016-05-31 9:41 ` [PATCH -v3 1/8] locking: Replace smp_cond_acquire with smp_cond_load_acquire Peter Zijlstra
2016-05-31 9:41 ` [PATCH -v3 2/8] locking: Introduce cmpwait() Peter Zijlstra
2016-05-31 9:41 ` [PATCH -v3 3/8] locking: Introduce smp_acquire__after_ctrl_dep Peter Zijlstra
2016-06-01 13:52 ` Boqun Feng
2016-06-01 16:22 ` Peter Zijlstra
2016-06-01 23:19 ` Boqun Feng
2016-05-31 9:41 ` [PATCH -v3 4/8] locking, arch: Update spin_unlock_wait() Peter Zijlstra
2016-06-01 11:24 ` Will Deacon
2016-06-01 11:37 ` Peter Zijlstra
2016-05-31 9:41 ` Peter Zijlstra [this message]
2016-05-31 9:41 ` [PATCH -v3 6/8] locking,netfilter: Fix nf_conntrack_lock() Peter Zijlstra
2016-05-31 9:41 ` [PATCH -v3 7/8] locking: Move smp_cond_load_acquire() and friends into asm-generic/barrier.h Peter Zijlstra
2016-05-31 20:01 ` Waiman Long
2016-06-01 9:31 ` Peter Zijlstra
2016-06-01 12:00 ` Will Deacon
2016-06-01 12:06 ` Peter Zijlstra
2016-06-01 12:13 ` Will Deacon
2016-06-01 12:45 ` Peter Zijlstra
2016-06-01 14:07 ` Will Deacon
2016-06-01 17:13 ` Peter Zijlstra
2016-06-01 16:53 ` Waiman Long
2016-05-31 9:41 ` [PATCH -v3 8/8] locking, tile: Provide TILE specific smp_acquire__after_ctrl_dep Peter Zijlstra
2016-05-31 15:32 ` Chris Metcalf
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