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authorLinus Torvalds <torvalds@linux-foundation.org>2014-03-31 10:59:39 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-03-31 10:59:39 -0700
commit462bf234a82ae1ae9d7628f59bc81022591e1348 (patch)
treef75eea7864ae7c72c0757d5d090e38f757b5cb2d /kernel/futex.c
parent455c6fdbd219161bd09b1165f11699d6d73de11c (diff)
parent6f008e72cd111a119b5d8de8c5438d892aae99eb (diff)
downloadlinux-462bf234a82ae1ae9d7628f59bc81022591e1348.tar.bz2
Merge branch 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core locking updates from Ingo Molnar: "The biggest change is the MCS spinlock generalization changes from Tim Chen, Peter Zijlstra, Jason Low et al. There's also lockdep fixes/enhancements from Oleg Nesterov, in particular a false negative fix related to lockdep_set_novalidate_class() usage" * 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (22 commits) locking/mutex: Fix debug checks locking/mutexes: Add extra reschedule point locking/mutexes: Introduce cancelable MCS lock for adaptive spinning locking/mutexes: Unlock the mutex without the wait_lock locking/mutexes: Modify the way optimistic spinners are queued locking/mutexes: Return false if task need_resched() in mutex_can_spin_on_owner() locking: Move mcs_spinlock.h into kernel/locking/ m68k: Skip futex_atomic_cmpxchg_inatomic() test futex: Allow architectures to skip futex_atomic_cmpxchg_inatomic() test Revert "sched/wait: Suppress Sparse 'variable shadowing' warning" lockdep: Change lockdep_set_novalidate_class() to use _and_name lockdep: Change mark_held_locks() to check hlock->check instead of lockdep_no_validate lockdep: Don't create the wrong dependency on hlock->check == 0 lockdep: Make held_lock->check and "int check" argument bool locking/mcs: Allow architecture specific asm files to be used for contended case locking/mcs: Order the header files in Kbuild of each architecture in alphabetical order sched/wait: Suppress Sparse 'variable shadowing' warning hung_task/Documentation: Fix hung_task_warnings description locking/mcs: Allow architectures to hook in to contended paths locking/mcs: Micro-optimize the MCS code, add extra comments ...
Diffstat (limited to 'kernel/futex.c')
-rw-r--r--kernel/futex.c37
1 files changed, 24 insertions, 13 deletions
diff --git a/kernel/futex.c b/kernel/futex.c
index 08ec814ad9d2..67dacaf93e56 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -157,7 +157,9 @@
* enqueue.
*/
+#ifndef CONFIG_HAVE_FUTEX_CMPXCHG
int __read_mostly futex_cmpxchg_enabled;
+#endif
/*
* Futex flags used to encode options to functions and preserve them across
@@ -2875,9 +2877,28 @@ SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);
}
-static int __init futex_init(void)
+static void __init futex_detect_cmpxchg(void)
{
+#ifndef CONFIG_HAVE_FUTEX_CMPXCHG
u32 curval;
+
+ /*
+ * This will fail and we want it. Some arch implementations do
+ * runtime detection of the futex_atomic_cmpxchg_inatomic()
+ * functionality. We want to know that before we call in any
+ * of the complex code paths. Also we want to prevent
+ * registration of robust lists in that case. NULL is
+ * guaranteed to fault and we get -EFAULT on functional
+ * implementation, the non-functional ones will return
+ * -ENOSYS.
+ */
+ if (cmpxchg_futex_value_locked(&curval, NULL, 0, 0) == -EFAULT)
+ futex_cmpxchg_enabled = 1;
+#endif
+}
+
+static int __init futex_init(void)
+{
unsigned int futex_shift;
unsigned long i;
@@ -2893,18 +2914,8 @@ static int __init futex_init(void)
&futex_shift, NULL,
futex_hashsize, futex_hashsize);
futex_hashsize = 1UL << futex_shift;
- /*
- * This will fail and we want it. Some arch implementations do
- * runtime detection of the futex_atomic_cmpxchg_inatomic()
- * functionality. We want to know that before we call in any
- * of the complex code paths. Also we want to prevent
- * registration of robust lists in that case. NULL is
- * guaranteed to fault and we get -EFAULT on functional
- * implementation, the non-functional ones will return
- * -ENOSYS.
- */
- if (cmpxchg_futex_value_locked(&curval, NULL, 0, 0) == -EFAULT)
- futex_cmpxchg_enabled = 1;
+
+ futex_detect_cmpxchg();
for (i = 0; i < futex_hashsize; i++) {
atomic_set(&futex_queues[i].waiters, 0);