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authorOleg Nesterov <oleg@redhat.com>2014-10-06 00:23:22 +0400
committerIngo Molnar <mingo@kernel.org>2014-10-28 12:46:05 +0300
commit009f60e2763568cdcd75bd1cf360c7c7165e2e60 (patch)
tree190e6cb5857bd0c2788939fe4004a128e655ec49 /arch/x86/include/asm/preempt.h
parent6419265899d9bd27e5ff9f8b43db3715407fc2ba (diff)
downloadlinux-009f60e2763568cdcd75bd1cf360c7c7165e2e60.tar.xz
sched: stop the unbound recursion in preempt_schedule_context()
preempt_schedule_context() does preempt_enable_notrace() at the end and this can call the same function again; exception_exit() is heavy and it is quite possible that need-resched is true again. 1. Change this code to dec preempt_count() and check need_resched() by hand. 2. As Linus suggested, we can use the PREEMPT_ACTIVE bit and avoid the enable/disable dance around __schedule(). But in this case we need to move into sched/core.c. 3. Cosmetic, but x86 forgets to declare this function. This doesn't really matter because it is only called by asm helpers, still it make sense to add the declaration into asm/preempt.h to match preempt_schedule(). Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Graf <agraf@suse.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Lameter <cl@linux.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Peter Anvin <hpa@zytor.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Chuck Ebbert <cebbert.lkml@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/20141005202322.GB27962@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/preempt.h')
-rw-r--r--arch/x86/include/asm/preempt.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h
index 7024c12f7bfe..400873450e33 100644
--- a/arch/x86/include/asm/preempt.h
+++ b/arch/x86/include/asm/preempt.h
@@ -105,6 +105,7 @@ static __always_inline bool should_resched(void)
# ifdef CONFIG_CONTEXT_TRACKING
extern asmlinkage void ___preempt_schedule_context(void);
# define __preempt_schedule_context() asm ("call ___preempt_schedule_context")
+ extern asmlinkage void preempt_schedule_context(void);
# endif
#endif