[Xen-devel] [PATCH for-4.5 v2 4/8] xen: arm: Use SMP barriers when that is all which is required.

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

SMP barriers can be used when all we care about is synchronising against other
processors.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Acked-by: Tim Deegan <tim@xxxxxxx>
---
v2: Turn cpu_die mb()s into smp_mb()s.
---
 xen/arch/arm/mm.c      |    2 +-
 xen/arch/arm/smpboot.c |   10 +++++-----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index f608020..ff19e39 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -967,7 +967,7 @@ void share_xen_page_with_guest(struct page_info *page,
     page->u.inuse.type_info |= PGT_validated | 1;
 
     page_set_owner(page, d);
-    wmb(); /* install valid domain ptr before updating refcnt. */
+    smp_wmb(); /* install valid domain ptr before updating refcnt. */
     ASSERT((page->count_info & ~PGC_xen_heap) == 0);
 
     /* Only add to the allocation list if the domain isn't dying. */
diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c
index a829957..ce68d34 100644
--- a/xen/arch/arm/smpboot.c
+++ b/xen/arch/arm/smpboot.c
@@ -298,12 +298,12 @@ void __cpuinit start_secondary(unsigned long 
boot_phys_offset,
 
     /* Run local notifiers */
     notify_cpu_starting(cpuid);
-    wmb();
+    smp_wmb();
 
     /* Now report this CPU is up */
     smp_up_cpu = MPIDR_INVALID;
     cpumask_set_cpu(cpuid, &cpu_online_map);
-    wmb();
+    smp_wmb();
 
     local_irq_enable();
     local_abort_enable();
@@ -330,7 +330,7 @@ void __cpu_disable(void)
 
     if ( cpu_disable_scheduler(cpu) )
         BUG();
-    mb();
+    smp_mb();
 
     /* Return to caller; eventually the IPI mechanism will unwind and the 
      * scheduler will drop to the idle loop, which will call stop_cpu(). */
@@ -411,10 +411,10 @@ void __cpu_die(unsigned int cpu)
         process_pending_softirqs();
         if ( (++i % 10) == 0 )
             printk(KERN_ERR "CPU %u still not dead...\n", cpu);
-        mb();
+        smp_mb();
     }
     cpu_is_dead = 0;
-    mb();
+    smp_mb();
 }
 
 /*
-- 
1.7.10.4


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