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preempt-rt: convert blackfin boot_lock to raw

PATCH New Frank Rowand 1 participant 1 message Sep 19, 2011

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Frank Rowand

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PATCH 1/1 preempt-rt: convert blackfin boot_lock to raw

The blackfin boot_lock is used by the secondary processor startup code. The locking task is the idle thread, which has idle->sched_class == &idle_sched_class. idle_sched_class->enqueue_task == NULL, so if the idle task blocks on the lock, the attempt to wake it when the lock becomes available will fail:

try_to_wake_up()
...

      activate_task()
         enqueue_task()
            p->sched_class->enqueue_task(rq, p, flags)

Fix by converting boot_lock to a raw spin lock.

This has not been compile or boot tested. The fix was needed by arm, this patch is for all other instances of "boot_lock" in other architectures.

Signed-off-by Frank Rowand <[email protected]>

---
arch/blackfin/mach-bf561/smp.c | 10 5 + 5 - 0 !

 1 file changed, 5 insertions(+), 5 deletions(-)
arch/blackfin/mach-bf561/smp.c +5 -5
Index: b/arch/blackfin/mach-bf561/smp.c
===================================================================
@@ -13,7 +13,7 @@
 #include <asm/dma.h>
 #include <asm/time.h>
 
-static DEFINE_SPINLOCK(boot_lock);
+static DEFINE_RAW_SPINLOCK(boot_lock);
 
 /*
  * platform_init_cpus() - Tell the world about how many cores we

@@ -70,8 +70,8 @@ void __cpuinit platform_secondary_init(u
 
 	/* We are done with local CPU inits, unblock the boot CPU. */
 	set_cpu_online(cpu, true);
-	spin_lock(&boot_lock);
-	spin_unlock(&boot_lock);
+	raw_spin_lock(&boot_lock);
+	raw_spin_unlock(&boot_lock);
 }
 
 int __cpuinit platform_boot_secondary(unsigned int cpu, struct task_struct *idle)

@@ -80,7 +80,7 @@ int __cpuinit platform_boot_secondary(un
 
 	printk(KERN_INFO "Booting Core B.\n");
 
-	spin_lock(&boot_lock);
+	raw_spin_lock(&boot_lock);
 
 	if ((bfin_read_SYSCR() & COREB_SRAM_INIT) == 0) {
 		/* CoreB already running, sending ipi to wakeup it */

@@ -101,7 +101,7 @@ int __cpuinit platform_boot_secondary(un
 
 	if (cpu_online(cpu)) {
 		/* release the lock and let coreb run */
-		spin_unlock(&boot_lock);
+		raw_spin_unlock(&boot_lock);
 		return 0;
 	} else
 		panic("CPU%u: processor failed to boot\n", cpu);