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

[Thomas Gleixner]

Commit-ID:  50d88758a3f9787cbdbdbc030560b815721eab4b
Gitweb:     http://git.kernel.org/tip/50d88758a3f9787cbdbdbc030560b815721eab4b
Author:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Wed, 18 Mar 2009 08:58:44 +0100
Commit:     Ingo Molnar <mingo@xxxxxxx>
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@xxxxxxxxxxxxx>
Cc: Steven Rostedt <srostedt@xxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>


---
 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);
 }
 
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