From: Ingo Molnar <mingo@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
"Paul E. McKenney" <paulmck@us.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [GIT PULL] locking fixes
Date: Thu, 17 Sep 2015 09:57:42 +0200 [thread overview]
Message-ID: <20150917075742.GA18117@gmail.com> (raw)
Linus,
Please pull the latest locking-urgent-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git locking-urgent-for-linus
# HEAD: 1975dbc276c6ab62230cf4f9df5ddc9ff0e0e473 locking/static_keys: Fix up the static keys documentation
Spinlock performance regression fix, plus documentation fixes.
Thanks,
Ingo
------------------>
Jonathan Corbet (2):
locking/static_keys: Fix a silly typo
locking/static_keys: Fix up the static keys documentation
Peter Zijlstra (2):
locking/qspinlock/x86: Fix performance regression under unaccelerated VMs
locking/qspinlock/x86: Only emit the test-and-set fallback when building guest support
Documentation/static-keys.txt | 4 ++--
arch/x86/include/asm/qspinlock.h | 19 ++++++++++++++-----
include/asm-generic/qspinlock.h | 4 ++--
include/linux/jump_label.h | 10 ++++------
kernel/locking/qspinlock.c | 2 +-
5 files changed, 23 insertions(+), 16 deletions(-)
diff --git a/Documentation/static-keys.txt b/Documentation/static-keys.txt
index f4cb0b2d5cd7..477927becacb 100644
--- a/Documentation/static-keys.txt
+++ b/Documentation/static-keys.txt
@@ -15,8 +15,8 @@ static_key_false()
DEFINE_STATIC_KEY_TRUE(key);
DEFINE_STATIC_KEY_FALSE(key);
-static_key_likely()
-statick_key_unlikely()
+static_branch_likely()
+static_branch_unlikely()
0) Abstract
diff --git a/arch/x86/include/asm/qspinlock.h b/arch/x86/include/asm/qspinlock.h
index 9d51fae1cba3..eaba08076030 100644
--- a/arch/x86/include/asm/qspinlock.h
+++ b/arch/x86/include/asm/qspinlock.h
@@ -39,18 +39,27 @@ static inline void queued_spin_unlock(struct qspinlock *lock)
}
#endif
-#define virt_queued_spin_lock virt_queued_spin_lock
-
-static inline bool virt_queued_spin_lock(struct qspinlock *lock)
+#ifdef CONFIG_PARAVIRT
+#define virt_spin_lock virt_spin_lock
+static inline bool virt_spin_lock(struct qspinlock *lock)
{
if (!static_cpu_has(X86_FEATURE_HYPERVISOR))
return false;
- while (atomic_cmpxchg(&lock->val, 0, _Q_LOCKED_VAL) != 0)
- cpu_relax();
+ /*
+ * On hypervisors without PARAVIRT_SPINLOCKS support we fall
+ * back to a Test-and-Set spinlock, because fair locks have
+ * horrible lock 'holder' preemption issues.
+ */
+
+ do {
+ while (atomic_read(&lock->val) != 0)
+ cpu_relax();
+ } while (atomic_cmpxchg(&lock->val, 0, _Q_LOCKED_VAL) != 0);
return true;
}
+#endif /* CONFIG_PARAVIRT */
#include <asm-generic/qspinlock.h>
diff --git a/include/asm-generic/qspinlock.h b/include/asm-generic/qspinlock.h
index 83bfb87f5bf1..e2aadbc7151f 100644
--- a/include/asm-generic/qspinlock.h
+++ b/include/asm-generic/qspinlock.h
@@ -111,8 +111,8 @@ static inline void queued_spin_unlock_wait(struct qspinlock *lock)
cpu_relax();
}
-#ifndef virt_queued_spin_lock
-static __always_inline bool virt_queued_spin_lock(struct qspinlock *lock)
+#ifndef virt_spin_lock
+static __always_inline bool virt_spin_lock(struct qspinlock *lock)
{
return false;
}
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 7f653e8f6690..f1094238ab2a 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -21,8 +21,8 @@
*
* DEFINE_STATIC_KEY_TRUE(key);
* DEFINE_STATIC_KEY_FALSE(key);
- * static_key_likely()
- * statick_key_unlikely()
+ * static_branch_likely()
+ * static_branch_unlikely()
*
* Jump labels provide an interface to generate dynamic branches using
* self-modifying code. Assuming toolchain and architecture support, if we
@@ -45,12 +45,10 @@
* statement, setting the key to true requires us to patch in a jump
* to the out-of-line of true branch.
*
- * In addtion to static_branch_{enable,disable}, we can also reference count
+ * In addition to static_branch_{enable,disable}, we can also reference count
* the key or branch direction via static_branch_{inc,dec}. Thus,
* static_branch_inc() can be thought of as a 'make more true' and
- * static_branch_dec() as a 'make more false'. The inc()/dec()
- * interface is meant to be used exclusively from the inc()/dec() for a given
- * key.
+ * static_branch_dec() as a 'make more false'.
*
* Since this relies on modifying code, the branch modifying functions
* must be considered absolute slow paths (machine wide synchronization etc.).
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index 337c8818541d..87e9ce6a63c5 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -289,7 +289,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
if (pv_enabled())
goto queue;
- if (virt_queued_spin_lock(lock))
+ if (virt_spin_lock(lock))
return;
/*
next reply other threads:[~2015-09-17 7:57 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-17 7:57 Ingo Molnar [this message]
-- strict thread matches above, loose matches on Subject: below --
2023-09-22 10:12 [GIT PULL] locking fixes Ingo Molnar
2023-09-22 20:19 ` pr-tracker-bot
2021-07-11 13:22 Ingo Molnar
2021-07-11 18:22 ` pr-tracker-bot
2021-04-11 12:14 Ingo Molnar
2021-04-11 18:56 ` pr-tracker-bot
2021-03-21 10:53 Ingo Molnar
2021-03-21 18:45 ` pr-tracker-bot
2020-12-27 9:50 Ingo Molnar
2020-12-27 17:27 ` pr-tracker-bot
2020-08-15 11:13 Ingo Molnar
2020-08-16 1:55 ` pr-tracker-bot
2020-01-18 17:53 Ingo Molnar
2020-01-18 21:05 ` pr-tracker-bot
2019-12-17 11:27 Ingo Molnar
2019-12-17 19:20 ` pr-tracker-bot
2019-04-20 7:30 Ingo Molnar
2019-04-20 16:51 ` Linus Torvalds
2019-04-21 18:23 ` Ingo Molnar
2019-04-20 19:25 ` pr-tracker-bot
2019-02-10 8:53 Ingo Molnar
2019-02-10 18:30 ` pr-tracker-bot
2018-10-05 9:36 Ingo Molnar
2018-10-05 23:06 ` Greg Kroah-Hartman
2018-09-15 12:56 Ingo Molnar
2018-07-30 17:49 Ingo Molnar
2018-03-25 8:49 Ingo Molnar
2018-02-15 0:50 Ingo Molnar
2018-01-17 15:24 Ingo Molnar
2018-01-22 9:43 ` Geert Uytterhoeven
2018-01-22 10:39 ` Peter Zijlstra
2018-01-12 13:45 Ingo Molnar
2017-12-15 15:55 Ingo Molnar
2017-10-14 16:01 Ingo Molnar
2017-03-07 20:27 Ingo Molnar
2017-02-28 7:57 Ingo Molnar
2017-02-28 18:37 ` Linus Torvalds
2017-05-03 23:21 ` Linus Torvalds
2017-05-04 5:40 ` Peter Zijlstra
[not found] ` <CA+55aFymvtCAYHdz__3Lj=YqmORB7_A-NXrw=+h+60znJVsDTw@mail.gmail.com>
2017-05-04 22:44 ` Greg Kroah-Hartman
2016-12-07 18:42 Ingo Molnar
2016-10-18 10:55 Ingo Molnar
2016-08-18 20:34 Ingo Molnar
2016-08-12 19:32 Ingo Molnar
2016-06-10 12:45 Ingo Molnar
2016-04-28 17:52 Ingo Molnar
2016-04-23 11:22 Ingo Molnar
2016-03-24 7:47 Ingo Molnar
2015-04-18 15:15 Ingo Molnar
2015-02-20 13:37 Ingo Molnar
2015-02-21 0:03 ` Linus Torvalds
2015-02-21 1:51 ` Linus Torvalds
2015-02-23 8:35 ` Christian Borntraeger
2015-02-21 5:07 ` Ingo Molnar
2015-02-21 5:16 ` Ingo Molnar
2015-02-21 5:28 ` Ingo Molnar
2015-01-11 8:39 Ingo Molnar
2014-10-31 11:06 Ingo Molnar
2014-04-16 11:39 Ingo Molnar
2014-01-15 18:15 Ingo Molnar
2009-12-10 19:45 Ingo Molnar
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