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| author | Will Deacon <will.deacon@arm.com> | 2010-12-02 18:01:49 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2010-12-04 11:18:08 +0000 |
| commit | 961ec6daa7b14f376c30d447a830fa4783a2112c (patch) | |
| tree | fd4952bd65fa9e991de7687eaef4b2e5af7a0e70 /arch/arm/kernel/perf_event_v6.c | |
| parent | 4d6b7a779be34e1df296abc1dc555134a8cf34af (diff) | |
| download | linux-961ec6daa7b14f376c30d447a830fa4783a2112c.tar.gz linux-961ec6daa7b14f376c30d447a830fa4783a2112c.tar.bz2 linux-961ec6daa7b14f376c30d447a830fa4783a2112c.zip | |
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_v6.c')
| -rw-r--r-- | arch/arm/kernel/perf_event_v6.c | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/arch/arm/kernel/perf_event_v6.c b/arch/arm/kernel/perf_event_v6.c index 3f427aae211d..c058bfc8532b 100644 --- a/arch/arm/kernel/perf_event_v6.c +++ b/arch/arm/kernel/perf_event_v6.c @@ -426,12 +426,12 @@ armv6pmu_enable_event(struct hw_perf_event *hwc, * Mask out the current event and set the counter to count the event * that we're interested in. */ - spin_lock_irqsave(&pmu_lock, flags); + raw_spin_lock_irqsave(&pmu_lock, flags); val = armv6_pmcr_read(); val &= ~mask; val |= evt; armv6_pmcr_write(val); - spin_unlock_irqrestore(&pmu_lock, flags); + raw_spin_unlock_irqrestore(&pmu_lock, flags); } static irqreturn_t @@ -500,11 +500,11 @@ armv6pmu_start(void) { unsigned long flags, val; - spin_lock_irqsave(&pmu_lock, flags); + raw_spin_lock_irqsave(&pmu_lock, flags); val = armv6_pmcr_read(); val |= ARMV6_PMCR_ENABLE; armv6_pmcr_write(val); - spin_unlock_irqrestore(&pmu_lock, flags); + raw_spin_unlock_irqrestore(&pmu_lock, flags); } static void @@ -512,11 +512,11 @@ armv6pmu_stop(void) { unsigned long flags, val; - spin_lock_irqsave(&pmu_lock, flags); + raw_spin_lock_irqsave(&pmu_lock, flags); val = armv6_pmcr_read(); val &= ~ARMV6_PMCR_ENABLE; armv6_pmcr_write(val); - spin_unlock_irqrestore(&pmu_lock, flags); + raw_spin_unlock_irqrestore(&pmu_lock, flags); } static int @@ -570,12 +570,12 @@ armv6pmu_disable_event(struct hw_perf_event *hwc, * of ETM bus signal assertion cycles. The external reporting should * be disabled and so this should never increment. */ - spin_lock_irqsave(&pmu_lock, flags); + raw_spin_lock_irqsave(&pmu_lock, flags); val = armv6_pmcr_read(); val &= ~mask; val |= evt; armv6_pmcr_write(val); - spin_unlock_irqrestore(&pmu_lock, flags); + raw_spin_unlock_irqrestore(&pmu_lock, flags); } static void @@ -599,12 +599,12 @@ armv6mpcore_pmu_disable_event(struct hw_perf_event *hwc, * Unlike UP ARMv6, we don't have a way of stopping the counters. We * simply disable the interrupt reporting. */ - spin_lock_irqsave(&pmu_lock, flags); + raw_spin_lock_irqsave(&pmu_lock, flags); val = armv6_pmcr_read(); val &= ~mask; val |= evt; armv6_pmcr_write(val); - spin_unlock_irqrestore(&pmu_lock, flags); + raw_spin_unlock_irqrestore(&pmu_lock, flags); } static const struct arm_pmu armv6pmu = { |