Commit f5e90281 authored Apr 10, 2006 by Roland McGrath Committed by Linus Torvalds Apr 11, 2006

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



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 <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent 491d4bed

fs/exec.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -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);

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