[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: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/exec.c b/fs/exec.c
index fffea1e..80fe7bc 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1368,6 +1368,22 @@
*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 @@
}
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;
- }
- while_each_thread(g,p);
-
+ 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);
+ }
read_unlock(&tasklist_lock);
if (unlikely(traced)) {