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authorWill Deacon <will.deacon@arm.com>2010-12-02 18:01:49 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2010-12-04 11:18:08 +0000
commit961ec6daa7b14f376c30d447a830fa4783a2112c (patch)
treefd4952bd65fa9e991de7687eaef4b2e5af7a0e70 /arch/arm/kernel/perf_event.c
parent4d6b7a779be34e1df296abc1dc555134a8cf34af (diff)
downloadlinux-961ec6daa7b14f376c30d447a830fa4783a2112c.tar.gz
ARM: 6521/1: perf: use raw_spinlock_t for pmu_lock
For kernels built with PREEMPT_RT, critical sections protected by standard spinlocks are preemptible. This is not acceptable on perf as (a) we may be scheduled onto a different CPU whilst reading/writing banked PMU registers and (b) the latency when reading the PMU registers becomes unpredictable. This patch upgrades the pmu_lock spinlock to a raw_spinlock instead. Reported-by: Jamie Iles <jamie@jamieiles.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/kernel/perf_event.c')
-rw-r--r--arch/arm/kernel/perf_event.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 50c197bfac0f..624e2a5de2b3 100644
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -32,7 +32,7 @@ static struct platform_device *pmu_device;
* Hardware lock to serialize accesses to PMU registers. Needed for the
* read/modify/write sequences.
*/
-static DEFINE_SPINLOCK(pmu_lock);
+static DEFINE_RAW_SPINLOCK(pmu_lock);
/*
* ARMv6 supports a maximum of 3 events, starting from index 1. If we add