From ccff286d85098ba5438e22aa2ea807fc1e18cf2f Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Thu, 11 Dec 2008 11:26:29 +0100
Subject: [PATCH] perf counters: group counter, fixes
Impact: bugfix
Check that a group does not span outside the context of a CPU or a task.
Also, do not allow deep recursive hierarchies.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/perf_counter.c | 39 ++++++++++++++++++++-------------------
1 file changed, 20 insertions(+), 19 deletions(-)
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index fa59fe8c02d5..278209c547a8 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -107,9 +107,6 @@ list_del_counter(struct perf_counter *counter, struct perf_counter_context *ctx)
list_del_init(&counter->list_entry);
- if (list_empty(&counter->sibling_list))
- return;
-
/*
* If this was a group counter with sibling counters then
* upgrade the siblings to singleton counters by adding them
@@ -395,9 +392,6 @@ counter_sched_in(struct perf_counter *counter,
struct perf_counter_context *ctx,
int cpu)
{
- if (!counter->active)
- return;
-
hw_perf_counter_enable(counter);
counter->active = 1;
counter->oncpu = cpu; /* TODO: put 'cpu' into cpuctx->cpu */
@@ -876,32 +870,39 @@ asmlinkage int sys_perf_counter_open(
return -EFAULT;
/*
- * Look up the group leader:
+ * Get the target context (task or percpu):
+ */
+ ctx = find_get_context(pid, cpu);
+ if (IS_ERR(ctx))
+ return PTR_ERR(ctx);
+
+ /*
+ * Look up the group leader (we will attach this counter to it):
*/
group_leader = NULL;
if (group_fd != -1) {
ret = -EINVAL;
group_file = fget_light(group_fd, &fput_needed);
if (!group_file)
- goto out_fput;
+ goto err_put_context;
if (group_file->f_op != &perf_fops)
- goto out_fput;
+ goto err_put_context;
group_leader = group_file->private_data;
/*
- * Do not allow a recursive hierarchy:
+ * Do not allow a recursive hierarchy (this new sibling
+ * becoming part of another group-sibling):
+ */
+ if (group_leader->group_leader != group_leader)
+ goto err_put_context;
+ /*
+ * Do not allow to attach to a group in a different
+ * task or CPU context:
*/
- if (group_leader->group_leader)
- goto out_fput;
+ if (group_leader->ctx != ctx)
+ goto err_put_context;
}
- /*
- * Get the target context (task or percpu):
- */
- ctx = find_get_context(pid, cpu);
- if (IS_ERR(ctx))
- return PTR_ERR(ctx);
-
ret = -ENOMEM;
counter = perf_counter_alloc(&hw_event, cpu, group_leader);
if (!counter)
--
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