Commit-ID: ca8f2d7f019a8547f39ddb9ed0144932f12807f2
Gitweb: http://git.kernel.org/tip/ca8f2d7f019a8547f39ddb9ed0144932f12807f2
Author: Paul Mackerras <paulus@xxxxxxxxx>
AuthorDate: Thu, 9 Apr 2009 14:42:56 +1000
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Thu, 9 Apr 2009 07:56:08 +0200
perf_counter: powerpc: add nmi_enter/nmi_exit calls
Impact: fix potential deadlocks on powerpc
Now that the core is using in_nmi() (added in e30e08f6, "perf_counter:
fix NMI race in task clock"), we need the powerpc perf_counter_interrupt
to call nmi_enter() and nmi_exit() in those cases where the interrupt
happens when interrupts are soft-disabled.
If interrupts were soft-enabled, we can treat it as a regular interrupt
and do irq_enter/irq_exit around the whole routine. This lets us get rid
of the test_perf_counter_pending() call at the end of
perf_counter_interrupt, thus simplifying things a little.
Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
LKML-Reference: <18909.31952.873098.336615@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
arch/powerpc/kernel/perf_counter.c | 31 +++++++++++++++++--------------
1 files changed, 17 insertions(+), 14 deletions(-)
diff --git a/arch/powerpc/kernel/perf_counter.c b/arch/powerpc/kernel/perf_counter.c
index c9d019f..bd76d0f 100644
--- a/arch/powerpc/kernel/perf_counter.c
+++ b/arch/powerpc/kernel/perf_counter.c
@@ -714,7 +714,7 @@ hw_perf_counter_init(struct perf_counter *counter)
* here so there is no possibility of being interrupted.
*/
static void record_and_restart(struct perf_counter *counter, long val,
- struct pt_regs *regs)
+ struct pt_regs *regs, int nmi)
{
s64 prev, delta, left;
int record = 0;
@@ -749,7 +749,7 @@ static void record_and_restart(struct perf_counter *counter, long val,
* Finally record data if requested.
*/
if (record)
- perf_counter_overflow(counter, 1, regs, 0);
+ perf_counter_overflow(counter, nmi, regs, 0);
}
/*
@@ -762,6 +762,17 @@ static void perf_counter_interrupt(struct pt_regs *regs)
struct perf_counter *counter;
long val;
int found = 0;
+ int nmi;
+
+ /*
+ * If interrupts were soft-disabled when this PMU interrupt
+ * occurred, treat it as an NMI.
+ */
+ nmi = !regs->softe;
+ if (nmi)
+ nmi_enter();
+ else
+ irq_enter();
for (i = 0; i < cpuhw->n_counters; ++i) {
counter = cpuhw->counter[i];
@@ -769,7 +780,7 @@ static void perf_counter_interrupt(struct pt_regs *regs)
if ((int)val < 0) {
/* counter has overflowed */
found = 1;
- record_and_restart(counter, val, regs);
+ record_and_restart(counter, val, regs, nmi);
}
}
@@ -796,18 +807,10 @@ static void perf_counter_interrupt(struct pt_regs *regs)
*/
mtspr(SPRN_MMCR0, cpuhw->mmcr[0]);
- /*
- * If we need a wakeup, check whether interrupts were soft-enabled
- * when we took the interrupt. If they were, we can wake stuff up
- * immediately; otherwise we'll have do the wakeup when interrupts
- * get soft-enabled.
- */
- if (test_perf_counter_pending() && regs->softe) {
- irq_enter();
- clear_perf_counter_pending();
- perf_counter_do_pending();
+ if (nmi)
+ nmi_exit();
+ else
irq_exit();
- }
}
void hw_perf_counter_setup(int cpu)
--
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