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authorLinus Torvalds <torvalds@linux-foundation.org>2016-09-09 20:54:29 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-09-09 20:54:29 +0300
commite45eeb43e67669f130c270a325383769d5fd73e2 (patch)
tree020de8523c77f7f4ff1455a04e0f33da50d2630b /arch
parent2771fc8ed60e43a0148a2f2c672a55b8f565f418 (diff)
parent2b9743441a312e0b0a2d87deae363eccbe9d0f00 (diff)
downloadlinux-e45eeb43e67669f130c270a325383769d5fd73e2.tar.xz
Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 fixes from Catalin Marinas: - smp_mb__before_spinlock() changed to smp_mb() on arm64 since the generic definition to smp_wmb() is not sufficient - avoid a recursive loop with the graph tracer by using using preempt_(enable|disable)_notrace in _percpu_(read|write) * tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: arm64: use preempt_disable_notrace in _percpu_read/write arm64: spinlocks: implement smp_mb__before_spinlock() as smp_mb()
Diffstat (limited to 'arch')
-rw-r--r--arch/arm64/include/asm/percpu.h8
-rw-r--r--arch/arm64/include/asm/spinlock.h10
2 files changed, 14 insertions, 4 deletions
diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h
index 0a456bef8c79..2fee2f59288c 100644
--- a/arch/arm64/include/asm/percpu.h
+++ b/arch/arm64/include/asm/percpu.h
@@ -199,19 +199,19 @@ static inline unsigned long __percpu_xchg(void *ptr, unsigned long val,
#define _percpu_read(pcp) \
({ \
typeof(pcp) __retval; \
- preempt_disable(); \
+ preempt_disable_notrace(); \
__retval = (typeof(pcp))__percpu_read(raw_cpu_ptr(&(pcp)), \
sizeof(pcp)); \
- preempt_enable(); \
+ preempt_enable_notrace(); \
__retval; \
})
#define _percpu_write(pcp, val) \
do { \
- preempt_disable(); \
+ preempt_disable_notrace(); \
__percpu_write(raw_cpu_ptr(&(pcp)), (unsigned long)(val), \
sizeof(pcp)); \
- preempt_enable(); \
+ preempt_enable_notrace(); \
} while(0) \
#define _pcp_protect(operation, pcp, val) \
diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
index e875a5a551d7..89206b568cd4 100644
--- a/arch/arm64/include/asm/spinlock.h
+++ b/arch/arm64/include/asm/spinlock.h
@@ -363,4 +363,14 @@ static inline int arch_read_trylock(arch_rwlock_t *rw)
#define arch_read_relax(lock) cpu_relax()
#define arch_write_relax(lock) cpu_relax()
+/*
+ * Accesses appearing in program order before a spin_lock() operation
+ * can be reordered with accesses inside the critical section, by virtue
+ * of arch_spin_lock being constructed using acquire semantics.
+ *
+ * In cases where this is problematic (e.g. try_to_wake_up), an
+ * smp_mb__before_spinlock() can restore the required ordering.
+ */
+#define smp_mb__before_spinlock() smp_mb()
+
#endif /* __ASM_SPINLOCK_H */