[tip:tracing/tasks] tracing: fix trace_find_cmdline()

Thomas Gleixner
2009-03-18T09:20:11Z

Commit-ID: 50d88758a3f9787cbdbdbc030560b815721eab4b
Gitweb: http://git.kernel.org/tip/50d88758a3f9787cbdbdbc030560b815721eab4b
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Wed, 18 Mar 2009 08:58:44 +0100
Commit: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 18 Mar 2009 10:10:17 +0100

tracing: fix trace_find_cmdline()

Impact: prevent stale command line output

In case there is no valid command line mapping for a pid
trace_find_cmdline() returns without updating the comm buffer. The
trace dump keeps the previous entry which results in confusing trace
output:

<idle>-0 [000] 280.702056 ....
<idle>-23456 [000] 280.702080 ....

Update the comm buffer with "<...>" when no mapping is found.

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>

---
kernel/trace/trace.c | 9 ++++-----
1 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index ca673c4..06c69a2 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -787,12 +787,11 @@ void trace_find_cmdline(int pid, char comm[])

__raw_spin_lock(&trace_cmdline_lock);
map = map_pid_to_cmdline[pid];
- if (map == NO_CMDLINE_MAP)
- goto out;
-
- strcpy(comm, saved_cmdlines[map]);
+ if (map != NO_CMDLINE_MAP)
+ strcpy(comm, saved_cmdlines[map]);
+ else
+ strcpy(comm, "<...>");

- out:
__raw_spin_unlock(&trace_cmdline_lock);
}