tracing: fix command line to pid reverse map

[pandora-kernel.git] / kernel / trace / trace.c

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 06c69a2..305c562 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -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;