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authorOleg Nesterov <oleg@redhat.com>2009-02-03 14:39:04 -0500
committerIngo Molnar <mingo@elte.hu>2009-02-03 16:50:58 -0500
commit229c4ef8ae56d69f8dec64533bf1c7f8070c1a4a (patch)
treee13a9ef3602f945ae51b73b592c8ae4d29e67ca3 /kernel/trace
parentb1792e367053968f2ddb48bc911d314143ce6242 (diff)
ftrace: do_each_pid_task() needs rcu lock
"ftrace: use struct pid" commit 978f3a45d9499c7a447ca7615455cefb63d44165 converted ftrace_pid_trace to "struct pid*". But we can't use do_each_pid_task() without rcu_read_lock() even if we know the pid itself can't go away (it was pinned in ftrace_pid_write). The exiting task can detach itself from this pid at any moment. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/trace')
-rw-r--r--kernel/trace/ftrace.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 7dcf6e9f2b04..9a236ffe2aa4 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1737,9 +1737,12 @@ static void clear_ftrace_pid(struct pid *pid)
1737{ 1737{
1738 struct task_struct *p; 1738 struct task_struct *p;
1739 1739
1740 rcu_read_lock();
1740 do_each_pid_task(pid, PIDTYPE_PID, p) { 1741 do_each_pid_task(pid, PIDTYPE_PID, p) {
1741 clear_tsk_trace_trace(p); 1742 clear_tsk_trace_trace(p);
1742 } while_each_pid_task(pid, PIDTYPE_PID, p); 1743 } while_each_pid_task(pid, PIDTYPE_PID, p);
1744 rcu_read_unlock();
1745
1743 put_pid(pid); 1746 put_pid(pid);
1744} 1747}
1745 1748
@@ -1747,9 +1750,11 @@ static void set_ftrace_pid(struct pid *pid)
1747{ 1750{
1748 struct task_struct *p; 1751 struct task_struct *p;
1749 1752
1753 rcu_read_lock();
1750 do_each_pid_task(pid, PIDTYPE_PID, p) { 1754 do_each_pid_task(pid, PIDTYPE_PID, p) {
1751 set_tsk_trace_trace(p); 1755 set_tsk_trace_trace(p);
1752 } while_each_pid_task(pid, PIDTYPE_PID, p); 1756 } while_each_pid_task(pid, PIDTYPE_PID, p);
1757 rcu_read_unlock();
1753} 1758}
1754 1759
1755static void clear_ftrace_pid_task(struct pid **pid) 1760static void clear_ftrace_pid_task(struct pid **pid)