51 lines
1.4 KiB
Diff
51 lines
1.4 KiB
Diff
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From d54c730eba63dfe0dcb8c7ab41514c564c159212 Mon Sep 17 00:00:00 2001
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From: Jiri Slaby <jirislaby@gmail.com>
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Date: Fri, 28 Aug 2009 14:08:17 +0200
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Subject: [PATCH] core: optimize setrlimit for current task
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References: FATE#305733
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Patch-mainline: no (later)
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Don't take tasklist lock for 'current'. It's not needed, since
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current->sighand/signal can't disappear.
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This improves serlimit called especially via sys_setrlimit.
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Signed-off-by: Jiri Slaby <jslaby@suse.cz>
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Cc: Oleg Nesterov <oleg@redhat.com>
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---
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kernel/sys.c | 16 ++++++++++------
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1 file changed, 10 insertions(+), 6 deletions(-)
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--- a/kernel/sys.c
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+++ b/kernel/sys.c
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@@ -1316,11 +1316,14 @@ int do_setrlimit(struct task_struct *tsk
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if (resource == RLIMIT_NOFILE && new_rlim->rlim_max > sysctl_nr_open)
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return -EPERM;
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- /* protect tsk->signal and tsk->sighand from disappearing */
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- read_lock(&tasklist_lock);
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- if (!tsk->sighand) {
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- retval = -ESRCH;
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- goto out;
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+ /* optimization: 'current' doesn't need locking, e.g. setrlimit */
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+ if (tsk != current) {
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+ /* protect tsk->signal and tsk->sighand from disappearing */
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+ read_lock(&tasklist_lock);
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+ if (!tsk->sighand) {
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+ retval = -ESRCH;
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+ goto out;
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+ }
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}
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retval = security_task_setrlimit(tsk, resource, new_rlim);
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@@ -1360,7 +1363,8 @@ int do_setrlimit(struct task_struct *tsk
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update_rlimit_cpu(tsk, new_rlim->rlim_cur);
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out:
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- read_unlock(&tasklist_lock);
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+ if (tsk != current)
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+ read_unlock(&tasklist_lock);
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return retval;
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}
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