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authorKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2013-11-08 21:28:05 +0100
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2013-11-08 21:28:05 +0100
commitbad97817dece759dd6c0b24f862b7d0ed588edda (patch)
treefcabaa3ae3e2f17236135e60dc875f47e852cc6d /lib/lockref.c
parentswiotlb-xen: missing include dma-direction.h (diff)
parentLinux 3.12-rc5 (diff)
downloadlinux-bad97817dece759dd6c0b24f862b7d0ed588edda.tar.xz
linux-bad97817dece759dd6c0b24f862b7d0ed588edda.zip
Merge tag 'v3.12-rc5' into stable/for-linus-3.13
Linux 3.12-rc5 Because the Stefano branch (for SWIOTLB ARM changes) is based on that. Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> * tag 'v3.12-rc5': (550 commits) Linux 3.12-rc5 watchdog: sunxi: Fix section mismatch watchdog: kempld_wdt: Fix bit mask definition watchdog: ts72xx_wdt: locking bug in ioctl ARM: exynos: dts: Update 5250 arch timer node with clock frequency parisc: let probe_kernel_read() capture access to page zero parisc: optimize variable initialization in do_page_fault parisc: fix interruption handler to respect pagefault_disable() parisc: mark parisc_terminate() noreturn and cold. parisc: remove unused syscall_ipi() function. parisc: kill SMP single function call interrupt parisc: Export flush_cache_page() (needed by lustre) vfs: allow O_PATH file descriptors for fstatfs() ext4: fix memory leak in xattr ARC: Ignore ptrace SETREGSET request for synthetic register "stop_pc" ALSA: hda - Sony VAIO Pro 13 (haswell) now has a working headset jack ALSA: hda - Add a headset mic model for ALC269 and friends ALSA: hda - Fix microphone for Sony VAIO Pro 13 (Haswell model) compiler/gcc4: Add quirk for 'asm goto' miscompilation bug Revert "i915: Update VGA arbiter support for newer devices" ...
Diffstat (limited to 'lib/lockref.c')
-rw-r--r--lib/lockref.c23
1 files changed, 20 insertions, 3 deletions
diff --git a/lib/lockref.c b/lib/lockref.c
index 677d036cf3c7..6f9d434c1521 100644
--- a/lib/lockref.c
+++ b/lib/lockref.c
@@ -4,6 +4,22 @@
#ifdef CONFIG_CMPXCHG_LOCKREF
/*
+ * Allow weakly-ordered memory architectures to provide barrier-less
+ * cmpxchg semantics for lockref updates.
+ */
+#ifndef cmpxchg64_relaxed
+# define cmpxchg64_relaxed cmpxchg64
+#endif
+
+/*
+ * Allow architectures to override the default cpu_relax() within CMPXCHG_LOOP.
+ * This is useful for architectures with an expensive cpu_relax().
+ */
+#ifndef arch_mutex_cpu_relax
+# define arch_mutex_cpu_relax() cpu_relax()
+#endif
+
+/*
* Note that the "cmpxchg()" reloads the "old" value for the
* failure case.
*/
@@ -14,12 +30,13 @@
while (likely(arch_spin_value_unlocked(old.lock.rlock.raw_lock))) { \
struct lockref new = old, prev = old; \
CODE \
- old.lock_count = cmpxchg64(&lockref->lock_count, \
- old.lock_count, new.lock_count); \
+ old.lock_count = cmpxchg64_relaxed(&lockref->lock_count, \
+ old.lock_count, \
+ new.lock_count); \
if (likely(old.lock_count == prev.lock_count)) { \
SUCCESS; \
} \
- cpu_relax(); \
+ arch_mutex_cpu_relax(); \
} \
} while (0)