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Commit a635cf04 authored by Carsten Emde's avatar Carsten Emde Committed by Ingo Molnar
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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: default avatarCarsten Emde <Carsten.Emde@osadl.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 50d88758

kernel/trace/trace.c

+11 −5
Original line number Diff line number Diff line
@@ -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;