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authorjohn stultz <johnstul@us.ibm.com>2009-12-14 18:00:05 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-15 08:53:24 -0800
commit4614a696bd1c3a9af3a08f0e5874830a85b889d4 (patch)
tree0b363d89ce612ab8557d49ab8b0f49b8520ffa66 /fs/exec.c
parent7e1e0ef22c9ba9f797d7c4448feee722584bba5c (diff)
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procfs: allow threads to rename siblings via /proc/pid/tasks/tid/comm
Setting a thread's comm to be something unique is a very useful ability and is helpful for debugging complicated threaded applications. However currently the only way to set a thread name is for the thread to name itself via the PR_SET_NAME prctl. However, there may be situations where it would be advantageous for a thread dispatcher to be naming the threads its managing, rather then having the threads self-describe themselves. This sort of behavior is available on other systems via the pthread_setname_np() interface. This patch exports a task's comm via proc/pid/comm and proc/pid/task/tid/comm interfaces, and allows thread siblings to write to these values. [akpm@linux-foundation.org: cleanups] Signed-off-by: John Stultz <johnstul@us.ibm.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Arjan van de Ven <arjan@infradead.org> Cc: Mike Fulton <fultonm@ca.ibm.com> Cc: Sean Foley <Sean_Foley@ca.ibm.com> Cc: Darren Hart <dvhltc@us.ibm.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/exec.c')
-rw-r--r--fs/exec.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/exec.c b/fs/exec.c
index c0c636e34f6..623a5cc3076 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -923,6 +923,15 @@ char *get_task_comm(char *buf, struct task_struct *tsk)
void set_task_comm(struct task_struct *tsk, char *buf)
{
task_lock(tsk);
+
+ /*
+ * Threads may access current->comm without holding
+ * the task lock, so write the string carefully.
+ * Readers without a lock may see incomplete new
+ * names but are safe from non-terminating string reads.
+ */
+ memset(tsk->comm, 0, TASK_COMM_LEN);
+ wmb();
strlcpy(tsk->comm, buf, sizeof(tsk->comm));
task_unlock(tsk);
perf_event_comm(tsk);