[tip:perfcounters/core] perf_counter: fix print debug irq disable

tip-bot for Peter Zijlstra
2009-05-13T06:22:29Z

Commit-ID: 5bb9efe33ea4001a17ab98186a40a134a3061d67
Gitweb: http://git.kernel.org/tip/5bb9efe33ea4001a17ab98186a40a134a3061d67
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Wed, 13 May 2009 08:12:51 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 13 May 2009 08:17:37 +0200

perf_counter: fix print debug irq disable

inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
bash/15802 [HC0[0]:SC0[0]:HE1:SE1] takes:
(sysrq_key_table_lock){?.....},

Don't unconditionally enable interrupts in the perf_counter_print_debug()
path.

[ Impact: fix potential deadlock pointed out by lockdep ]

LKML-Reference: <new-submission>
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

---
arch/x86/kernel/cpu/perf_counter.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c
index da27419..f7772ff 100644
--- a/arch/x86/kernel/cpu/perf_counter.c
+++ b/arch/x86/kernel/cpu/perf_counter.c
@@ -621,12 +621,13 @@ void perf_counter_print_debug(void)
{
u64 ctrl, status, overflow, pmc_ctrl, pmc_count, prev_left, fixed;
struct cpu_hw_counters *cpuc;
+ unsigned long flags;
int cpu, idx;

if (!x86_pmu.num_counters)
return;

- local_irq_disable();
+ local_irq_save(flags);

cpu = smp_processor_id();
cpuc = &per_cpu(cpu_hw_counters, cpu);
@@ -664,7 +665,7 @@ void perf_counter_print_debug(void)
pr_info("CPU#%d: fixed-PMC%d count: %016llx\n",
cpu, idx, pmc_count);
}
- local_irq_enable();
+ local_irq_restore(flags);
}

static void x86_pmu_disable(struct perf_counter *counter)