Messages in this thread Patch in this message | | | Date | Fri, 29 Jan 2016 03:33:14 -0800 | From | "tip-bot for Michael S. Tsirkin" <> | Subject | [tip:locking/core] locking/x86: Use mb() around clflush() |
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Commit-ID: ca59809ff6d572ae58fc6bedf7500f5a60fdbd64 Gitweb: http://git.kernel.org/tip/ca59809ff6d572ae58fc6bedf7500f5a60fdbd64 Author: Michael S. Tsirkin <mst@redhat.com> AuthorDate: Thu, 28 Jan 2016 19:02:51 +0200 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Fri, 29 Jan 2016 09:40:10 +0100
locking/x86: Use mb() around clflush()
The following commit:
f8e617f4582995f ("sched/idle/x86: Optimize unnecessary mwait_idle() resched IPIs")
adds memory barriers around clflush(), but this seems wrong for UP since barrier() has no effect on clflush(). We really want MFENCE, so switch to mb() instead.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Len Brown <len.brown@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <bitbucket@online.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: virtualization <virtualization@lists.linux-foundation.org> Link: http://lkml.kernel.org/r/1453921746-16178-5-git-send-email-mst@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org> --- arch/x86/kernel/process.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 9f7c21c..9decee2 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -418,9 +418,9 @@ static void mwait_idle(void) if (!current_set_polling_and_test()) { trace_cpu_idle_rcuidle(1, smp_processor_id()); if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) { - smp_mb(); /* quirk */ + mb(); /* quirk */ clflush((void *)¤t_thread_info()->flags); - smp_mb(); /* quirk */ + mb(); /* quirk */ } __monitor((void *)¤t_thread_info()->flags, 0, 0);
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