From: Jason Low <jason.low2@hp.com>
To: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Davidlohr Bueso <dave@stgolabs.net>,
Tim Chen <tim.c.chen@linux.intel.com>,
Aswin Chandramouleeswaran <aswin@hp.com>
Cc: LKML <linux-kernel@vger.kernel.org>, Jason Low <jason.low2@hp.com>
Subject: [PATCH 1/2] locking/mutex: Further refactor mutex_spin_on_owner()
Date: Wed, 8 Apr 2015 12:39:19 -0700 [thread overview]
Message-ID: <1428521960-5268-2-git-send-email-jason.low2@hp.com> (raw)
In-Reply-To: <1428521960-5268-1-git-send-email-jason.low2@hp.com>
Similar to what Linus suggested for rwsem_spin_on_owner(), in
mutex_spin_on_owner() instead of having while (true) and breaking
out of the spin loop on lock->owner != owner, we can have the loop
directly check for while (lock->owner == owner) to improve the
readability of the code.
Signed-off-by: Jason Low <jason.low2@hp.com>
---
kernel/locking/mutex.c | 14 ++++----------
1 files changed, 4 insertions(+), 10 deletions(-)
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 16b2d3c..4cccea6 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -224,20 +224,14 @@ ww_mutex_set_context_slowpath(struct ww_mutex *lock,
static noinline
bool mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner)
{
- bool ret;
+ bool ret = true;
rcu_read_lock();
- while (true) {
- /* Return success when the lock owner changed */
- if (lock->owner != owner) {
- ret = true;
- break;
- }
-
+ while (lock->owner == owner) {
/*
* Ensure we emit the owner->on_cpu, dereference _after_
- * checking lock->owner still matches owner, if that fails,
- * owner might point to free()d memory, if it still matches,
+ * checking lock->owner still matches owner. If that fails,
+ * owner might point to freed memory. If it still matches,
* the rcu_read_lock() ensures the memory stays valid.
*/
barrier();
--
1.7.2.5
next prev parent reply other threads:[~2015-04-08 19:39 UTC|newest]
Thread overview: 108+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-08 19:39 [PATCH 0/2] locking: Simplify mutex and rwsem spinning code Jason Low
2015-04-08 19:39 ` Jason Low [this message]
2015-04-09 9:00 ` [tip:locking/core] locking/mutex: Further simplify mutex_spin_on_owner() tip-bot for Jason Low
2015-04-08 19:39 ` [PATCH 2/2] locking/rwsem: Use a return variable in rwsem_spin_on_owner() Jason Low
2015-04-09 5:37 ` Ingo Molnar
2015-04-09 6:40 ` Jason Low
2015-04-09 7:53 ` Ingo Molnar
2015-04-09 16:47 ` Linus Torvalds
2015-04-09 17:56 ` Paul E. McKenney
2015-04-09 18:08 ` Linus Torvalds
2015-04-09 18:16 ` Linus Torvalds
2015-04-09 18:39 ` Paul E. McKenney
2015-04-10 9:00 ` [PATCH] mutex: Speed up mutex_spin_on_owner() by not taking the RCU lock Ingo Molnar
2015-04-10 9:12 ` Ingo Molnar
2015-04-10 9:21 ` [PATCH] uaccess: Add __copy_from_kernel_inatomic() primitive Ingo Molnar
2015-04-10 11:14 ` [PATCH] x86/uaccess: Implement get_kernel() Ingo Molnar
2015-04-10 11:27 ` [PATCH] mutex: Improve mutex_spin_on_owner() code generation Ingo Molnar
2015-04-10 12:08 ` [PATCH] x86: Align jump targets to 1 byte boundaries Ingo Molnar
2015-04-10 12:18 ` [PATCH] x86: Pack function addresses tightly as well Ingo Molnar
2015-04-10 12:30 ` [PATCH] x86: Pack loops " Ingo Molnar
2015-04-10 13:46 ` Borislav Petkov
2015-05-15 9:40 ` [tip:x86/asm] " tip-bot for Ingo Molnar
2015-05-17 6:03 ` [tip:x86/apic] " tip-bot for Ingo Molnar
2015-05-15 9:39 ` [tip:x86/asm] x86: Pack function addresses " tip-bot for Ingo Molnar
2015-05-15 18:36 ` Linus Torvalds
2015-05-15 20:52 ` Denys Vlasenko
2015-05-17 5:58 ` Ingo Molnar
2015-05-17 7:09 ` Ingo Molnar
2015-05-17 7:30 ` Ingo Molnar
2015-05-18 9:28 ` Denys Vlasenko
2015-05-19 21:38 ` [RFC PATCH] x86/64: Optimize the effective instruction cache footprint of kernel functions Ingo Molnar
2015-05-20 0:47 ` Linus Torvalds
2015-05-20 12:21 ` Denys Vlasenko
2015-05-21 11:36 ` Ingo Molnar
2015-05-21 11:38 ` Denys Vlasenko
2016-04-16 21:08 ` Denys Vlasenko
2015-05-20 13:09 ` Ingo Molnar
2015-05-20 11:29 ` Denys Vlasenko
2015-05-21 13:28 ` Ingo Molnar
2015-05-21 14:03 ` Ingo Molnar
2015-04-10 12:50 ` [PATCH] x86: Align jump targets to 1 byte boundaries Denys Vlasenko
2015-04-10 13:18 ` H. Peter Anvin
2015-04-10 17:54 ` Ingo Molnar
2015-04-10 18:32 ` H. Peter Anvin
2015-04-11 14:41 ` Markus Trippelsdorf
2015-04-12 10:14 ` Ingo Molnar
2015-04-13 16:23 ` Markus Trippelsdorf
2015-04-13 17:26 ` Markus Trippelsdorf
2015-04-13 18:31 ` Linus Torvalds
2015-04-13 19:09 ` Markus Trippelsdorf
2015-04-14 5:38 ` Ingo Molnar
2015-04-14 8:23 ` Markus Trippelsdorf
2015-04-14 9:16 ` Ingo Molnar
2015-04-14 11:17 ` Markus Trippelsdorf
2015-04-14 12:09 ` Ingo Molnar
2015-04-10 18:48 ` Linus Torvalds
2015-04-12 23:44 ` Maciej W. Rozycki
2015-04-10 19:23 ` Daniel Borkmann
2015-04-11 13:48 ` Markus Trippelsdorf
2015-04-10 13:19 ` Borislav Petkov
2015-04-10 13:54 ` Denys Vlasenko
2015-04-10 14:01 ` Borislav Petkov
2015-04-10 14:53 ` Denys Vlasenko
2015-04-10 15:25 ` Borislav Petkov
2015-04-10 15:48 ` Denys Vlasenko
2015-04-10 15:54 ` Borislav Petkov
2015-04-10 21:44 ` Borislav Petkov
2015-04-10 18:54 ` Linus Torvalds
2015-04-10 14:10 ` Paul E. McKenney
2015-04-11 14:28 ` Josh Triplett
2015-04-11 9:20 ` [PATCH] x86: Turn off GCC branch probability heuristics Ingo Molnar
2015-04-11 17:41 ` Linus Torvalds
2015-04-11 18:57 ` Thomas Gleixner
2015-04-11 19:35 ` Linus Torvalds
2015-04-12 5:47 ` Ingo Molnar
2015-04-12 6:20 ` Markus Trippelsdorf
2015-04-12 10:15 ` Ingo Molnar
2015-04-12 7:56 ` Mike Galbraith
2015-04-12 7:41 ` Ingo Molnar
2015-04-12 8:07 ` Ingo Molnar
2015-04-12 21:11 ` Jan Hubicka
2015-05-14 11:59 ` [PATCH] x86: Align jump targets to 1 byte boundaries Denys Vlasenko
2015-05-14 18:17 ` Ingo Molnar
2015-05-14 19:04 ` Denys Vlasenko
2015-05-14 19:44 ` Ingo Molnar
2015-05-15 15:45 ` Josh Triplett
2015-05-17 5:34 ` Ingo Molnar
2015-05-17 19:18 ` Josh Triplett
2015-05-18 6:48 ` Ingo Molnar
2015-05-15 9:39 ` [tip:x86/asm] x86: Align jump targets to 1-byte boundaries tip-bot for Ingo Molnar
2015-04-10 11:34 ` [PATCH] x86/uaccess: Implement get_kernel() Peter Zijlstra
2015-04-10 18:04 ` Ingo Molnar
2015-04-10 17:49 ` Linus Torvalds
2015-04-10 18:04 ` Ingo Molnar
2015-04-10 18:09 ` Linus Torvalds
2015-04-10 14:20 ` [PATCH] mutex: Speed up mutex_spin_on_owner() by not taking the RCU lock Paul E. McKenney
2015-04-10 17:44 ` Ingo Molnar
2015-04-10 18:05 ` Paul E. McKenney
2015-04-09 19:43 ` [PATCH 2/2] locking/rwsem: Use a return variable in rwsem_spin_on_owner() Jason Low
2015-04-09 19:58 ` Paul E. McKenney
2015-04-09 20:58 ` Jason Low
2015-04-09 21:07 ` Paul E. McKenney
2015-04-09 19:59 ` Davidlohr Bueso
2015-04-09 20:36 ` Jason Low
2015-04-10 2:43 ` Andev
2015-04-10 9:04 ` Ingo Molnar
2015-04-08 19:49 ` [PATCH 0/2] locking: Simplify mutex and rwsem spinning code Davidlohr Bueso
2015-04-08 20:10 ` Jason Low
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