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perf_counter: Sanitize counter->mutex

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s/counter->mutex/counter->child_mutex/ and make sure its only
used to protect child_list.

The usage in __perf_counter_exit_task() doesn't appear to be
problematic since ctx->mutex also covers anything related to fd
tear-down.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <20090523163012.533186528@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-05-23 18:28:56 +02:00 committed by Ingo Molnar
parent e220d2dcb9
commit fccc714b31
2 changed files with 22 additions and 32 deletions
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7
include/linux/perf_counter.h
View File

@ -452,9 +452,6 @@ struct perf_counter {
struct perf_counter_context *ctx;
struct file *filp;
struct perf_counter *parent;
struct list_head child_list;
/*
* These accumulate total time (in nanoseconds) that children
* counters have been enabled and running, respectively.
@ -465,7 +462,9 @@ struct perf_counter {
/*
* Protect attach/detach and child_list:
*/
struct mutex mutex;
struct mutex child_mutex;
struct list_head child_list;
struct perf_counter *parent;
int oncpu;
int cpu;

47
kernel/perf_counter.c
View File

@ -111,6 +111,10 @@ static void put_ctx(struct perf_counter_context *ctx)
}
}
/*
* Add a counter from the lists for its context.
* Must be called with ctx->mutex and ctx->lock held.
*/
static void
list_add_counter(struct perf_counter *counter, struct perf_counter_context *ctx)
{
@ -136,7 +140,7 @@ list_add_counter(struct perf_counter *counter, struct perf_counter_context *ctx)
/*
* Remove a counter from the lists for its context.
* Must be called with counter->mutex and ctx->mutex held.
* Must be called with ctx->mutex and ctx->lock held.
*/
static void
list_del_counter(struct perf_counter *counter, struct perf_counter_context *ctx)
@ -276,7 +280,7 @@ static void __perf_counter_remove_from_context(void *info)
/*
* Remove the counter from a task's (or a CPU's) list of counters.
*
* Must be called with counter->mutex and ctx->mutex held.
* Must be called with ctx->mutex held.
*
* CPU counters are removed with a smp call. For task counters we only
* call when the task is on a CPU.
@ -1407,11 +1411,7 @@ static int perf_release(struct inode *inode, struct file *file)
file->private_data = NULL;
mutex_lock(&ctx->mutex);
mutex_lock(&counter->mutex);
perf_counter_remove_from_context(counter);
mutex_unlock(&counter->mutex);
mutex_unlock(&ctx->mutex);
free_counter(counter);
@ -1437,7 +1437,7 @@ perf_read_hw(struct perf_counter *counter, char __user *buf, size_t count)
if (counter->state == PERF_COUNTER_STATE_ERROR)
return 0;
mutex_lock(&counter->mutex);
mutex_lock(&counter->child_mutex);
values[0] = perf_counter_read(counter);
n = 1;
if (counter->hw_event.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
@ -1446,7 +1446,7 @@ perf_read_hw(struct perf_counter *counter, char __user *buf, size_t count)
if (counter->hw_event.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
values[n++] = counter->total_time_running +
atomic64_read(&counter->child_total_time_running);
mutex_unlock(&counter->mutex);
mutex_unlock(&counter->child_mutex);
if (count < n * sizeof(u64))
return -EINVAL;
@ -1510,11 +1510,11 @@ static void perf_counter_for_each_child(struct perf_counter *counter,
{
struct perf_counter *child;
mutex_lock(&counter->mutex);
mutex_lock(&counter->child_mutex);
func(counter);
list_for_each_entry(child, &counter->child_list, child_list)
func(child);
mutex_unlock(&counter->mutex);
mutex_unlock(&counter->child_mutex);
}
static void perf_counter_for_each(struct perf_counter *counter,
@ -1522,11 +1522,11 @@ static void perf_counter_for_each(struct perf_counter *counter,
{
struct perf_counter *child;
mutex_lock(&counter->mutex);
mutex_lock(&counter->child_mutex);
perf_counter_for_each_sibling(counter, func);
list_for_each_entry(child, &counter->child_list, child_list)
perf_counter_for_each_sibling(child, func);
mutex_unlock(&counter->mutex);
mutex_unlock(&counter->child_mutex);
}
static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
@ -3106,7 +3106,9 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event,
if (!group_leader)
group_leader = counter;
mutex_init(&counter->mutex);
mutex_init(&counter->child_mutex);
INIT_LIST_HEAD(&counter->child_list);
INIT_LIST_HEAD(&counter->list_entry);
INIT_LIST_HEAD(&counter->event_entry);
INIT_LIST_HEAD(&counter->sibling_list);
@ -3114,8 +3116,6 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event,
mutex_init(&counter->mmap_mutex);
INIT_LIST_HEAD(&counter->child_list);
counter->cpu = cpu;
counter->hw_event = *hw_event;
counter->group_leader = group_leader;
@ -3346,10 +3346,9 @@ inherit_counter(struct perf_counter *parent_counter,
/*
* Link this into the parent counter's child list
*/
mutex_lock(&parent_counter->mutex);
mutex_lock(&parent_counter->child_mutex);
list_add_tail(&child_counter->child_list, &parent_counter->child_list);
mutex_unlock(&parent_counter->mutex);
mutex_unlock(&parent_counter->child_mutex);
return child_counter;
}
@ -3396,9 +3395,9 @@ static void sync_child_counter(struct perf_counter *child_counter,
/*
* Remove this counter from the parent's list
*/
mutex_lock(&parent_counter->mutex);
mutex_lock(&parent_counter->child_mutex);
list_del_init(&child_counter->child_list);
mutex_unlock(&parent_counter->mutex);
mutex_unlock(&parent_counter->child_mutex);
/*
* Release the parent counter, if this was the last
@ -3414,17 +3413,9 @@ __perf_counter_exit_task(struct task_struct *child,
{
struct perf_counter *parent_counter;
/*
* Protect against concurrent operations on child_counter
* due its fd getting closed, etc.
*/
mutex_lock(&child_counter->mutex);
update_counter_times(child_counter);
list_del_counter(child_counter, child_ctx);
mutex_unlock(&child_counter->mutex);
parent_counter = child_counter->parent;
/*
* It can happen that parent exits first, and has counters