From 42eb088ed246a5a817bb45a8b32fe234cf1c0f8b Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 19 Nov 2013 16:41:49 +0100 Subject: sched: Avoid NULL dereference on sd_busy Commit 37dc6b50cee9 ("sched: Remove unnecessary iteration over sched domains to update nr_busy_cpus") forgot to clear 'sd_busy' under some conditions leading to a possible NULL deref in set_cpu_sd_state_idle(). Reported-by: Anton Blanchard Cc: Preeti U Murthy Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20131118113701.GF3866@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar --- kernel/sched/core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel/sched/core.c') diff --git a/kernel/sched/core.c b/kernel/sched/core.c index c1808606ee5f..a1591ca7eb5a 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4910,8 +4910,9 @@ static void update_top_cache_domain(int cpu) if (sd) { id = cpumask_first(sched_domain_span(sd)); size = cpumask_weight(sched_domain_span(sd)); - rcu_assign_pointer(per_cpu(sd_busy, cpu), sd->parent); + sd = sd->parent; /* sd_busy */ } + rcu_assign_pointer(per_cpu(sd_busy, cpu), sd); rcu_assign_pointer(per_cpu(sd_llc, cpu), sd); per_cpu(sd_llc_size, cpu) = size; -- cgit v1.2.2 From 0515973ffb16c2852a1bb1df2ca1456556faaaa5 Mon Sep 17 00:00:00 2001 From: Shigeru Yoshida Date: Sun, 17 Nov 2013 12:12:36 +0900 Subject: sched: Fix a trivial typo in comments Fix a trivial typo in rq_attach_root(). Signed-off-by: Shigeru Yoshida Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20131117.121236.1990617639803941055.shigeru.yoshida@gmail.com Signed-off-by: Ingo Molnar --- kernel/sched/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/sched/core.c') diff --git a/kernel/sched/core.c b/kernel/sched/core.c index a1591ca7eb5a..718730dd0480 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4762,7 +4762,7 @@ static void rq_attach_root(struct rq *rq, struct root_domain *rd) cpumask_clear_cpu(rq->cpu, old_rd->span); /* - * If we dont want to free the old_rt yet then + * If we dont want to free the old_rd yet then * set old_rd to NULL to skip the freeing later * in this function: */ -- cgit v1.2.2 From 32e475d76a3e40879cd9ee4f69b19615062280d7 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 21 Nov 2013 12:41:44 +0100 Subject: sched: Expose preempt_schedule_irq() Tony reported that aa0d53260596 ("ia64: Use preempt_schedule_irq") broke PREEMPT=n builds on ia64. Ok, wrapped my brain around it. I tripped over the magic asm foo which has a single need_resched check and schedule point for both sys call return and interrupt return. So you need the schedule_preempt_irq() for kernel preemption from interrupt return while on a normal syscall preemption a schedule would be sufficient. But using schedule_preempt_irq() is not harmful here in any way. It just sets the preempt_active bit also in cases where it would not be required. Even on preempt=n kernels adding the preempt_active bit is completely harmless. So instead of having an extra function, moving the existing one out of the ifdef PREEMPT looks like the sanest thing to do. It would also allow getting rid of various other sti/schedule/cli asm magic in other archs. Reported-and-Tested-by: Tony Luck Fixes: aa0d53260596 ("ia64: Use preempt_schedule_irq") Signed-off-by: Thomas Gleixner [slightly edited Changelog] Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1311211230030.30673@ionos.tec.linutronix.de Signed-off-by: Ingo Molnar --- kernel/sched/core.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'kernel/sched/core.c') diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 718730dd0480..e85cda20ab2b 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2660,6 +2660,7 @@ asmlinkage void __sched notrace preempt_schedule(void) } while (need_resched()); } EXPORT_SYMBOL(preempt_schedule); +#endif /* CONFIG_PREEMPT */ /* * this is the entry point to schedule() from kernel preemption @@ -2693,8 +2694,6 @@ asmlinkage void __sched preempt_schedule_irq(void) exception_exit(prev_state); } -#endif /* CONFIG_PREEMPT */ - int default_wake_function(wait_queue_t *curr, unsigned mode, int wake_flags, void *key) { -- cgit v1.2.2