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perf_counter: avoid recursion

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Tracepoint events like lock_acquire and software counters like
pagefaults can recurse into the perf counter code again, avoid that.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090323172417.152096433@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-03-23 18:22:07 +01:00 committed by Ingo Molnar
parent f4a2deb486
commit 96f6d44443
2 changed files with 33 additions and 0 deletions
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7
include/linux/perf_counter.h
View file

@ -328,6 +328,13 @@ struct perf_cpu_context {
int active_oncpu;
int max_pertask;
int exclusive;
/*
* Recursion avoidance:
*
* task, softirq, irq, nmi context
*/
int recursion[4];
};
/*

26
kernel/perf_counter.c
View file

@ -23,6 +23,7 @@
#include <linux/mm.h>
#include <linux/vmstat.h>
#include <linux/rculist.h>
#include <linux/hardirq.h>
#include <asm/irq_regs.h>
@ -1532,10 +1533,31 @@ static void perf_swcounter_ctx_event(struct perf_counter_context *ctx,
rcu_read_unlock();
}
static int *perf_swcounter_recursion_context(struct perf_cpu_context *cpuctx)
{
if (in_nmi())
return &cpuctx->recursion[3];
if (in_irq())
return &cpuctx->recursion[2];
if (in_softirq())
return &cpuctx->recursion[1];
return &cpuctx->recursion[0];
}
static void __perf_swcounter_event(enum perf_event_types type, u32 event,
u64 nr, int nmi, struct pt_regs *regs)
{
struct perf_cpu_context *cpuctx = &get_cpu_var(perf_cpu_context);
int *recursion = perf_swcounter_recursion_context(cpuctx);
if (*recursion)
goto out;
(*recursion)++;
barrier();
perf_swcounter_ctx_event(&cpuctx->ctx, type, event, nr, nmi, regs);
if (cpuctx->task_ctx) {
@ -1543,6 +1565,10 @@ static void __perf_swcounter_event(enum perf_event_types type, u32 event,
nr, nmi, regs);
}
barrier();
(*recursion)--;
out:
put_cpu_var(perf_cpu_context);
}