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-rw-r--r--arch/arm/mach-ux500/platsmp.c22
1 files changed, 15 insertions, 7 deletions
diff --git a/arch/arm/mach-ux500/platsmp.c b/arch/arm/mach-ux500/platsmp.c
index ddedbc80c41..f71175a766d 100644
--- a/arch/arm/mach-ux500/platsmp.c
+++ b/arch/arm/mach-ux500/platsmp.c
@@ -27,6 +27,19 @@
*/
volatile int __cpuinitdata pen_release = -1;
+/*
+ * Write pen_release in a way that is guaranteed to be visible to all
+ * observers, irrespective of whether they're taking part in coherency
+ * or not. This is necessary for the hotplug code to work reliably.
+ */
+static void write_pen_release(int val)
+{
+ pen_release = val;
+ smp_wmb();
+ __cpuc_flush_dcache_area((void *)&pen_release, sizeof(pen_release));
+ outer_clean_range(__pa(&pen_release), __pa(&pen_release + 1));
+}
+
static DEFINE_SPINLOCK(boot_lock);
void __cpuinit platform_secondary_init(unsigned int cpu)
@@ -42,7 +55,7 @@ void __cpuinit platform_secondary_init(unsigned int cpu)
* let the primary processor know we're out of the
* pen, then head off into the C entry point
*/
- pen_release = -1;
+ write_pen_release(-1);
/*
* Synchronise with the boot thread.
@@ -66,9 +79,7 @@ int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
* the holding pen - release it, then wait for it to flag
* that it has been released by resetting pen_release.
*/
- pen_release = cpu;
- __cpuc_flush_dcache_area((void *)&pen_release, sizeof(pen_release));
- outer_clean_range(__pa(&pen_release), __pa(&pen_release) + 1);
+ write_pen_release(cpu);
smp_cross_call(cpumask_of(cpu), 1);
@@ -89,9 +100,6 @@ int __cpuinit boot_secondary(unsigned int cpu, struct task_struct *idle)
static void __init wakeup_secondary(void)
{
- /* nobody is to be released from the pen yet */
- pen_release = -1;
-
/*
* write the address of secondary startup into the backup ram register
* at offset 0x1FF4, then write the magic number 0xA1FEED01 to the