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tracing: fix command line to pid reverse map 

Impact: fix command line to pid mapping

map_cmdline_to_pid[] is checked in trace_save_cmdline(), but never
updated. This results in stale pid to command line mappings and the
tracer output will associate the wrong comm string.

Signed-off-by: Carsten Emde <Carsten.Emde@osadl.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Carsten Emde 2009-03-18 09:00:41 +01:00 committed by Ingo Molnar
parent 50d88758a3
commit a635cf0497
1 changed files with 11 additions and 5 deletions
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16
kernel/trace/trace.c
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@ -738,8 +738,7 @@ void trace_stop_cmdline_recording(void);
static void trace_save_cmdline(struct task_struct *tsk)
{
unsigned map;
unsigned idx;
unsigned pid, idx;
if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT))
return;
@ -757,10 +756,17 @@ static void trace_save_cmdline(struct task_struct *tsk)
if (idx == NO_CMDLINE_MAP) {
idx = (cmdline_idx + 1) % SAVED_CMDLINES;
map = map_cmdline_to_pid[idx];
if (map != NO_CMDLINE_MAP)
map_pid_to_cmdline[map] = NO_CMDLINE_MAP;
/*
* Check whether the cmdline buffer at idx has a pid
* mapped. We are going to overwrite that entry so we
* need to clear the map_pid_to_cmdline. Otherwise we
* would read the new comm for the old pid.
*/
pid = map_cmdline_to_pid[idx];
if (pid != NO_CMDLINE_MAP)
map_pid_to_cmdline[pid] = NO_CMDLINE_MAP;
map_cmdline_to_pid[idx] = tsk->pid;
map_pid_to_cmdline[tsk->pid] = idx;
cmdline_idx = idx;