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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2009-06-03 14:01:36 +0200
committerIngo Molnar <mingo@elte.hu>2009-06-03 14:57:03 +0200
commita96bbc16418bc691317f265d6bf98ba941ca9c1a (patch)
tree136e40a12a94653e8224d6c09d5384b4140e0532 /kernel
parent8229289b607682f90b946ad2c319526303c17700 (diff)
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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.c25
1 files changed, 14 insertions, 11 deletions
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 317cef7..ab44554 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, &current->perf_counter_list);
mutex_unlock(&current->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: