aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorDaniel Thompson <daniel.thompson@linaro.org>2015-01-21 14:27:28 +0000
committerDaniel Thompson <daniel.thompson@linaro.org>2015-01-21 17:02:55 +0000
commit6f30731ba69aa87b7165507e035d08939eb5491a (patch)
tree5221ac4fb4a4aa2eb83f5075f99890629537502f
parent73ff7c8248d13dc9288b905d9c04e0e703ca2d00 (diff)
downloadlinux-6f30731ba69aa87b7165507e035d08939eb5491a.tar.gz
arm: perf: Make v7 support FIQ-safe
armv7pmu_disable_event() is called during irq handling. If irq handling switches over to fiq then the spin locks in this function risk deadlock. Both armv7_pmnc_disable_counter() and armv7_pmnc_disable_intens() are unconditional co-processor writes. I haven't yet come up with an schedule where other users of pmu_lock would break if interleaved with these calls so I have simply removed them. The other change required us to avoid calling irq_work_run() when run from a FIQ handler. The pended work will either be dispatched by the irq work IPI or by a timer handler. Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
-rw-r--r--arch/arm/kernel/perf_event_v7.c11
1 files changed, 2 insertions, 9 deletions
diff --git a/arch/arm/kernel/perf_event_v7.c b/arch/arm/kernel/perf_event_v7.c
index 8993770c47de..08f426486d3e 100644
--- a/arch/arm/kernel/perf_event_v7.c
+++ b/arch/arm/kernel/perf_event_v7.c
@@ -744,7 +744,6 @@ static void armv7pmu_enable_event(struct perf_event *event)
static void armv7pmu_disable_event(struct perf_event *event)
{
- unsigned long flags;
struct hw_perf_event *hwc = &event->hw;
struct arm_pmu *cpu_pmu = to_arm_pmu(event->pmu);
struct pmu_hw_events *events = this_cpu_ptr(cpu_pmu->hw_events);
@@ -757,11 +756,6 @@ static void armv7pmu_disable_event(struct perf_event *event)
}
/*
- * Disable counter and interrupt
- */
- raw_spin_lock_irqsave(&events->pmu_lock, flags);
-
- /*
* Disable counter
*/
armv7_pmnc_disable_counter(idx);
@@ -770,8 +764,6 @@ static void armv7pmu_disable_event(struct perf_event *event)
* Disable interrupt for this counter
*/
armv7_pmnc_disable_intens(idx);
-
- raw_spin_unlock_irqrestore(&events->pmu_lock, flags);
}
static irqreturn_t armv7pmu_handle_irq(int irq_num, void *dev)
@@ -831,7 +823,8 @@ static irqreturn_t armv7pmu_handle_irq(int irq_num, void *dev)
* platforms that can have the PMU interrupts raised as an NMI, this
* will not work.
*/
- irq_work_run();
+ if (!in_nmi())
+ irq_work_run();
return IRQ_HANDLED;
}