evie/android_kernel_oneplus_msm8998
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[PATCH] coredump: optimize ->mm users traversal

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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>
This commit is contained in:
Oleg Nesterov 2006-06-26 00:26:05 -07:00 • committed by Linus Torvalds
parent 2ceb8693ef
commit aceecc0412
1 changed files with 26 additions and 10 deletions
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36
fs/exec.c
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@ -1368,6 +1368,22 @@ static void format_corename(char *corename, const char *pattern, long signr)
*out_ptr = 0; *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) static void zap_threads (struct mm_struct *mm)
{ {
struct task_struct *g, *p; struct task_struct *g, *p;
@ -1385,16 +1401,16 @@ static void zap_threads (struct mm_struct *mm)
} }
read_lock(&tasklist_lock); read_lock(&tasklist_lock);
do_each_thread(g,p) for_each_process(g) {
if (mm == p->mm && p != tsk) { p = g;
force_sig_specific(SIGKILL, p); do {
mm->core_waiters++; if (p->mm) {
if (unlikely(p->ptrace) && if (p->mm == mm)
unlikely(p->parent->mm == mm)) zap_process(p, &traced);
traced = 1; break;
} }
while_each_thread(g,p); } while ((p = next_thread(p)) != g);
}
read_unlock(&tasklist_lock); read_unlock(&tasklist_lock);
if (unlikely(traced)) { if (unlikely(traced)) {