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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2009-06-03 14:01:36 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-06-03 14:57:03 +0200 |
| commit | a96bbc16418bc691317f265d6bf98ba941ca9c1a (patch) | |
| tree | 136e40a12a94653e8224d6c09d5384b4140e0532 /kernel | |
| parent | 8229289b607682f90b946ad2c319526303c17700 (diff) | |
| download | linux-stable-a96bbc16418bc691317f265d6bf98ba941ca9c1a.tar.gz linux-stable-a96bbc16418bc691317f265d6bf98ba941ca9c1a.tar.bz2 linux-stable-a96bbc16418bc691317f265d6bf98ba941ca9c1a.zip | |
perf_counter: Fix race in counter initialization
We need the PID namespace and counter ID available when the
counter overflows and we need to generate a sample event.
[ Impact: fix kernel crash with high-frequency sampling ]
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
[ fixed a further crash and cleaned up the initialization a bit ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/perf_counter.c | 25 |
1 files changed, 14 insertions, 11 deletions
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 317cef78a388..ab4455447f84 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -48,6 +48,8 @@ int sysctl_perf_counter_priv __read_mostly; /* do we need to be privileged */ int sysctl_perf_counter_mlock __read_mostly = 512; /* 'free' kb per user */ int sysctl_perf_counter_limit __read_mostly = 100000; /* max NMIs per second */ +static atomic64_t perf_counter_id; + /* * Lock for (sysadmin-configurable) counter reservations: */ @@ -3351,14 +3353,18 @@ perf_counter_alloc(struct perf_counter_attr *attr, mutex_init(&counter->mmap_mutex); - counter->cpu = cpu; + counter->cpu = cpu; counter->attr = *attr; - counter->group_leader = group_leader; - counter->pmu = NULL; - counter->ctx = ctx; - counter->oncpu = -1; + counter->group_leader = group_leader; + counter->pmu = NULL; + counter->ctx = ctx; + counter->oncpu = -1; + + counter->ns = get_pid_ns(current->nsproxy->pid_ns); + counter->id = atomic64_inc_return(&perf_counter_id); + + counter->state = PERF_COUNTER_STATE_INACTIVE; - counter->state = PERF_COUNTER_STATE_INACTIVE; if (attr->disabled) counter->state = PERF_COUNTER_STATE_OFF; @@ -3402,6 +3408,8 @@ done: err = PTR_ERR(pmu); if (err) { + if (counter->ns) + put_pid_ns(counter->ns); kfree(counter); return ERR_PTR(err); } @@ -3419,8 +3427,6 @@ done: return counter; } -static atomic64_t perf_counter_id; - /** * sys_perf_counter_open - open a performance counter, associate it to a task/cpu * @@ -3515,9 +3521,6 @@ SYSCALL_DEFINE5(perf_counter_open, list_add_tail(&counter->owner_entry, ¤t->perf_counter_list); mutex_unlock(¤t->perf_counter_mutex); - counter->ns = get_pid_ns(current->nsproxy->pid_ns); - counter->id = atomic64_inc_return(&perf_counter_id); - fput_light(counter_file, fput_needed2); out_fput: |