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authorTörök Edwin <edwintorok@gmail.com>2008-11-23 12:39:07 +0200
committerIngo Molnar <mingo@elte.hu>2008-11-23 11:53:49 +0100
commitcffa10aecb6891f090a4d53a075bc40c082c45fc (patch)
tree825b264f70bc5c5aaa2882e8dfba75e366238b1e /kernel/trace
parent8d7c6a96164651dbbab449ef0b5c20ae1f76a3a1 (diff)
tracing/stack-tracer: fix locking and refcounts
Impact: fix refcounting/object-access bug Hold mmap_sem while looking up/accessing vma. Hold the RCU lock while using the task we looked up. Signed-off-by: Török Edwin <edwintorok@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/trace.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index dedf35f3697..4c3bd82cec4 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1462,11 +1462,15 @@ static inline int seq_print_user_ip(struct trace_seq *s, struct mm_struct *mm,
int ret = 1;
if (mm) {
- const struct vm_area_struct *vma = find_vma(mm, ip);
+ const struct vm_area_struct *vma;
+
+ down_read(&mm->mmap_sem);
+ vma = find_vma(mm, ip);
if (vma) {
file = vma->vm_file;
vmstart = vma->vm_start;
}
+ up_read(&mm->mmap_sem);
}
if (file) {
ret = trace_seq_path(s, &file->f_path);
@@ -1494,10 +1498,9 @@ seq_print_userip_objs(const struct userstack_entry *entry, struct trace_seq *s,
*/
rcu_read_lock();
task = find_task_by_vpid(entry->ent.tgid);
- rcu_read_unlock();
-
if (task)
mm = get_task_mm(task);
+ rcu_read_unlock();
}
for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {