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Subject[tip:x86/timers] x86/tsc: Move sync cleanup to a safe place
Commit-ID:  ce68ad5a095f151426cab18cc8fad9c968421da3
Gitweb: http://git.kernel.org/tip/ce68ad5a095f151426cab18cc8fad9c968421da3
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Sat, 19 Nov 2016 13:47:40 +0000
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Tue, 29 Nov 2016 17:29:48 +0100

x86/tsc: Move sync cleanup to a safe place

Cleaning up the stop marker on the control CPU is wrong when we want to add
retry support. Move the cleanup to the starting CPU.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/20161119134017.892095627@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
arch/x86/kernel/tsc_sync.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c
index 1770f60..8642223 100644
--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -267,11 +267,6 @@ void check_tsc_sync_source(int cpu)
}

/*
- * Reset it - in case this is a second bootup:
- */
- atomic_set(&stop_count, 0);
-
- /*
* Wait for the target to start or to skip the test:
*/
while (atomic_read(&start_count) != cpus - 1) {
@@ -360,6 +355,11 @@ void check_tsc_sync_target(void)
*/
while (atomic_read(&stop_count) != cpus)
cpu_relax();
+
+ /*
+ * Reset it for the next sync test:
+ */
+ atomic_set(&stop_count, 0);
}

#endif /* CONFIG_SMP */
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