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Commit aceecc04 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
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[PATCH] coredump: optimize ->mm users traversal 



zap_threads() iterates over all threads to find those ones which share
current->mm.  All threads in the thread group share the same ->mm, so we can
skip entire thread group if it has another ->mm.

This patch shifts the killing of thread group into the newly added
zap_process() function.  This looks as unnecessary complication, but it is
used in further patches.

Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: default avatarRoland McGrath <roland@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 2ceb8693

fs/exec.c

+26 −10
Original line number Diff line number Diff line
@@ -1368,6 +1368,22 @@ static void format_corename(char *corename, const char *pattern, long signr) 
	*out_ptr = 0;

}



static void zap_process(struct task_struct *start, int *ptraced)

{

	struct task_struct *t;



	t = start;

	do {

		if (t != current && t->mm) {

			t->mm->core_waiters++;

			force_sig_specific(SIGKILL, t);

			if (unlikely(t->ptrace) &&

			    unlikely(t->parent->mm == t->mm))

				*ptraced = 1;

		}

	} while ((t = next_thread(t)) != start);

}



static void zap_threads (struct mm_struct *mm)

{

	struct task_struct *g, *p;
@@ -1385,16 +1401,16 @@ static void zap_threads (struct mm_struct *mm) 
	}



	read_lock(&tasklist_lock);

	do_each_thread(g,p)

		if (mm == p->mm && p != tsk) {

			force_sig_specific(SIGKILL, p);

			mm->core_waiters++;

			if (unlikely(p->ptrace) &&

			    unlikely(p->parent->mm == mm))

				traced = 1;

	for_each_process(g) {

		p = g;

		do {

			if (p->mm) {

				if (p->mm == mm)

					zap_process(p, &traced);

				break;

			}

		} while ((p = next_thread(p)) != g);

	}

	while_each_thread(g,p);



	read_unlock(&tasklist_lock);



	if (unlikely(traced)) {