Messages in this thread Patch in this message | | | Date | Mon, 28 Apr 2008 10:11:29 +0200 | From | Heiko Carstens <> | Subject | Re: [PATCH] sched: missing locking in sched_domains code |
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Subject: [PATCH] sched: fix locking in arch_reinit_sched_domains
From: Heiko Carstens <heiko.carstens@de.ibm.com>
Concurrent calls to detach_destroy_domains and arch_init_sched_domains were prevented by the old scheduler subsystem cpu hotplug mutex. When this got converted to get_online_cpus() the locking got broken. Unlike before now several processes can concurrently enter the critical sections that were protected by the old lock.
So use the already present doms_cur_mutex to protect these sections again.
Cc: Gautham R Shenoy <ego@in.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Paul Jackson <pj@sgi.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> --- kernel/sched.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-)
Index: linux-2.6/kernel/sched.c =================================================================== --- linux-2.6.orig/kernel/sched.c +++ linux-2.6/kernel/sched.c @@ -311,6 +311,16 @@ static DEFINE_SPINLOCK(task_group_lock); /* doms_cur_mutex serializes access to doms_cur[] array */ static DEFINE_MUTEX(doms_cur_mutex); +static inline void lock_doms_cur(void) +{ + mutex_lock(&doms_cur_mutex); +} + +static inline void unlock_doms_cur(void) +{ + mutex_unlock(&doms_cur_mutex); +} + #ifdef CONFIG_FAIR_GROUP_SCHED #ifdef CONFIG_USER_SCHED # define INIT_TASK_GROUP_LOAD (2*NICE_0_LOAD) @@ -358,21 +368,9 @@ static inline void set_task_rq(struct ta #endif } -static inline void lock_doms_cur(void) -{ - mutex_lock(&doms_cur_mutex); -} - -static inline void unlock_doms_cur(void) -{ - mutex_unlock(&doms_cur_mutex); -} - #else static inline void set_task_rq(struct task_struct *p, unsigned int cpu) { } -static inline void lock_doms_cur(void) { } -static inline void unlock_doms_cur(void) { } #endif /* CONFIG_GROUP_SCHED */ @@ -7813,8 +7811,10 @@ int arch_reinit_sched_domains(void) int err; get_online_cpus(); + lock_doms_cur(); detach_destroy_domains(&cpu_online_map); err = arch_init_sched_domains(&cpu_online_map); + unlock_doms_cur(); put_online_cpus(); return err;
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