projects/linux·commit f5e90281

[PATCH] process accounting: take original leader's start_time in non-leader exec

f5e90281 · Roland McGrath <[email protected]> · 2006-04-10 22:54:16 -07:00

The only record we have of the real-time age of a process, regardless of
execs it's done, is start_time.  When a non-leader thread exec, the
original start_time of the process is lost.  Things looking at the
real-time age of the process are fooled, for example the process accounting
record when the process finally dies.  This change makes the oldest
start_time stick around with the process after a non-leader exec.  This way
the association between PID and start_time is kept constant, which seems
correct to me.

Signed-off-by: Roland McGrath <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Commit
f5e902817fee1589badca1284f49eecc0ef0c200
Parents
491d4bed

Changes

1 files changed · +12 −0

FileStatusAddDelContent
fs/exec.cmodified+12−0View file

fs/exec.c

View file
diff --git a/fs/exec.c b/fs/exec.c
index 4d38ad0..3234a0c 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -678,6 +678,18 @@ static int de_thread(struct task_struct *tsk)
while (leader->exit_state != EXIT_ZOMBIE)
yield();
+ /*
+ * The only record we have of the real-time age of a
+ * process, regardless of execs it's done, is start_time.
+ * All the past CPU time is accumulated in signal_struct
+ * from sister threads now dead. But in this non-leader
+ * exec, nothing survives from the original leader thread,
+ * whose birth marks the true age of this process now.
+ * When we take on its identity by switching to its PID, we
+ * also take its birthdate (always earlier than our own).
+ */
+ current->start_time = leader->start_time;
+
spin_lock(&leader->proc_lock);
spin_lock(&current->proc_lock);
proc_dentry1 = proc_pid_unhash(current);