diff options
| author | Ingo Molnar <mingo@elte.hu> | 2009-05-15 08:26:20 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-05-15 09:47:06 +0200 |
| commit | 9029a5e3801f1cc7cdaab80169d82427acf928d8 (patch) | |
| tree | e2acb45f70744ffd5c47c31be67e482df2ef17c4 | |
| parent | 1c80f4b598d9b075a2a0be694e28be93a6702bcc (diff) | |
perf_counter: x86: Protect against infinite loops in intel_pmu_handle_irq()
intel_pmu_handle_irq() can lock up in an infinite loop if the hardware
does not allow the acking of irqs. Alas, this happened in testing so
make this robust and emit a warning if it happens in the future.
Also, clean up the IRQ handlers a bit.
[ Impact: improve perfcounter irq/nmi handling robustness ]
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | arch/x86/kernel/cpu/perf_counter.c | 25 |
1 files changed, 18 insertions, 7 deletions
diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index 46a82d1e4cbe..5a7f718eb1e1 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -722,9 +722,13 @@ static void intel_pmu_save_and_restart(struct perf_counter *counter) */ static int intel_pmu_handle_irq(struct pt_regs *regs, int nmi) { - int bit, cpu = smp_processor_id(); + struct cpu_hw_counters *cpuc; + struct cpu_hw_counters; + int bit, cpu, loops; u64 ack, status; - struct cpu_hw_counters *cpuc = &per_cpu(cpu_hw_counters, cpu); + + cpu = smp_processor_id(); + cpuc = &per_cpu(cpu_hw_counters, cpu); perf_disable(); status = intel_pmu_get_status(); @@ -733,7 +737,13 @@ static int intel_pmu_handle_irq(struct pt_regs *regs, int nmi) return 0; } + loops = 0; again: + if (++loops > 100) { + WARN_ONCE(1, "perfcounters: irq loop stuck!\n"); + return 1; + } + inc_irq_stat(apic_perf_irqs); ack = status; for_each_bit(bit, (unsigned long *)&status, X86_PMC_IDX_MAX) { @@ -765,13 +775,14 @@ again: static int amd_pmu_handle_irq(struct pt_regs *regs, int nmi) { - int cpu = smp_processor_id(); - struct cpu_hw_counters *cpuc = &per_cpu(cpu_hw_counters, cpu); - u64 val; - int handled = 0; + int cpu, idx, throttle = 0, handled = 0; + struct cpu_hw_counters *cpuc; struct perf_counter *counter; struct hw_perf_counter *hwc; - int idx, throttle = 0; + u64 val; + + cpu = smp_processor_id(); + cpuc = &per_cpu(cpu_hw_counters, cpu); if (++cpuc->interrupts == PERFMON_MAX_INTERRUPTS) { throttle = 1; |