Currently, we don't enforce any ordering for updates to the lppaca
when enabling dtl logging, so we may end up enabling logging before the
index fields have been established.
This change adds a smp_wmb() before doing the actual enable.
Signed-off-by: Jeremy Kerr <j...@ozlabs.org>
---
arch/powerpc/platforms/pseries/dtl.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/powerpc/platforms/pseries/dtl.c
b/arch/powerpc/platforms/pseries/dtl.c
index dc9b0f8..fafcaa0 100644
--- a/arch/powerpc/platforms/pseries/dtl.c
+++ b/arch/powerpc/platforms/pseries/dtl.c
@@ -107,6 +107,10 @@ static int dtl_enable(struct dtl *dtl)
/* set our initial buffer indices */
dtl->last_idx = lppaca[dtl->cpu].dtl_idx = 0;
+ /* ensure that our updates to the lppaca fields have occurred before
+ * we actually enable the logging */
+ smp_wmb();
+
/* enable event logging */
lppaca[dtl->cpu].dtl_enable_mask = dtl_event_mask;
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