X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=blobdiff_plain;f=kernel%2Fsched%2Fmembarrier.c;h=a39bed2c784f42be244082e5d80320f72e9d8daf;hb=c172e0a3e8e65a4c6fffec5bc4d6de08d6f894f7;hp=fced54ad0f3d406466cc239ae40b14be1426f9d0;hpb=c6d68c1c4a4d6611fc0f8145d764226571d737ca;p=linux.git

diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c
index fced54ad0f3d..a39bed2c784f 100644
--- a/kernel/sched/membarrier.c
+++ b/kernel/sched/membarrier.c
@@ -66,7 +66,6 @@ void membarrier_exec_mmap(struct mm_struct *mm)
 static int membarrier_global_expedited(void)
 {
 	int cpu;
-	bool fallback = false;
 	cpumask_var_t tmpmask;
 
 	if (num_online_cpus() == 1)
@@ -78,15 +77,8 @@ static int membarrier_global_expedited(void)
 	 */
 	smp_mb();	/* system call entry is not a mb. */
 
-	/*
-	 * Expedited membarrier commands guarantee that they won't
-	 * block, hence the GFP_NOWAIT allocation flag and fallback
-	 * implementation.
-	 */
-	if (!zalloc_cpumask_var(&tmpmask, GFP_NOWAIT)) {
-		/* Fallback for OOM. */
-		fallback = true;
-	}
+	if (!zalloc_cpumask_var(&tmpmask, GFP_KERNEL))
+		return -ENOMEM;
 
 	cpus_read_lock();
 	rcu_read_lock();
@@ -117,18 +109,15 @@ static int membarrier_global_expedited(void)
 		if (p->flags & PF_KTHREAD)
 			continue;
 
-		if (!fallback)
-			__cpumask_set_cpu(cpu, tmpmask);
-		else
-			smp_call_function_single(cpu, ipi_mb, NULL, 1);
+		__cpumask_set_cpu(cpu, tmpmask);
 	}
 	rcu_read_unlock();
-	if (!fallback) {
-		preempt_disable();
-		smp_call_function_many(tmpmask, ipi_mb, NULL, 1);
-		preempt_enable();
-		free_cpumask_var(tmpmask);
-	}
+
+	preempt_disable();
+	smp_call_function_many(tmpmask, ipi_mb, NULL, 1);
+	preempt_enable();
+
+	free_cpumask_var(tmpmask);
 	cpus_read_unlock();
 
 	/*
@@ -143,7 +132,6 @@ static int membarrier_global_expedited(void)
 static int membarrier_private_expedited(int flags)
 {
 	int cpu;
-	bool fallback = false;
 	cpumask_var_t tmpmask;
 	struct mm_struct *mm = current->mm;
 
@@ -168,15 +156,8 @@ static int membarrier_private_expedited(int flags)
 	 */
 	smp_mb();	/* system call entry is not a mb. */
 
-	/*
-	 * Expedited membarrier commands guarantee that they won't
-	 * block, hence the GFP_NOWAIT allocation flag and fallback
-	 * implementation.
-	 */
-	if (!zalloc_cpumask_var(&tmpmask, GFP_NOWAIT)) {
-		/* Fallback for OOM. */
-		fallback = true;
-	}
+	if (!zalloc_cpumask_var(&tmpmask, GFP_KERNEL))
+		return -ENOMEM;
 
 	cpus_read_lock();
 	rcu_read_lock();
@@ -195,20 +176,16 @@ static int membarrier_private_expedited(int flags)
 			continue;
 		rcu_read_lock();
 		p = rcu_dereference(cpu_rq(cpu)->curr);
-		if (p && p->mm == mm) {
-			if (!fallback)
-				__cpumask_set_cpu(cpu, tmpmask);
-			else
-				smp_call_function_single(cpu, ipi_mb, NULL, 1);
-		}
+		if (p && p->mm == mm)
+			__cpumask_set_cpu(cpu, tmpmask);
 	}
 	rcu_read_unlock();
-	if (!fallback) {
-		preempt_disable();
-		smp_call_function_many(tmpmask, ipi_mb, NULL, 1);
-		preempt_enable();
-		free_cpumask_var(tmpmask);
-	}
+
+	preempt_disable();
+	smp_call_function_many(tmpmask, ipi_mb, NULL, 1);
+	preempt_enable();
+
+	free_cpumask_var(tmpmask);
 	cpus_read_unlock();
 
 	/*
@@ -264,7 +241,7 @@ static int sync_runqueues_membarrier_state(struct mm_struct *mm)
 		struct rq *rq = cpu_rq(cpu);
 		struct task_struct *p;
 
-		p = rcu_dereference(&rq->curr);
+		p = rcu_dereference(rq->curr);
 		if (p && p->mm == mm)
 			__cpumask_set_cpu(cpu, tmpmask);
 	}