[v3,24/45] infiniband: ehca: Use get/put_online_cpus_atomic() to prevent CPU offline

Submitted by Srivatsa S. Bhat on June 27, 2013, 7:56 p.m.


Message ID 20130627195648.29830.64721.stgit@srivatsabhat.in.ibm.com
State Not Applicable
Delegated to: David Miller
Headers show

Commit Message

Srivatsa S. Bhat June 27, 2013, 7:56 p.m.
Once stop_machine() is gone from the CPU offline path, we won't be able
to depend on disabling preemption to prevent CPUs from going offline
from under us.

Use the get/put_online_cpus_atomic() APIs to prevent CPUs from going
offline, while invoking from atomic context.

Cc: Hoang-Nam Nguyen <hnguyen@de.ibm.com>
Cc: Christoph Raisch <raisch@de.ibm.com>
Cc: Roland Dreier <roland@kernel.org>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Hal Rosenstock <hal.rosenstock@gmail.com>
Cc: linux-rdma@vger.kernel.org
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>

 drivers/infiniband/hw/ehca/ehca_irq.c |    5 +++++
 1 file changed, 5 insertions(+)

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diff --git a/drivers/infiniband/hw/ehca/ehca_irq.c b/drivers/infiniband/hw/ehca/ehca_irq.c
index 8615d7c..ace901e 100644
--- a/drivers/infiniband/hw/ehca/ehca_irq.c
+++ b/drivers/infiniband/hw/ehca/ehca_irq.c
@@ -43,6 +43,7 @@ 
 #include <linux/slab.h>
 #include <linux/smpboot.h>
+#include <linux/cpu.h>
 #include "ehca_classes.h"
 #include "ehca_irq.h"
@@ -703,6 +704,7 @@  static void queue_comp_task(struct ehca_cq *__cq)
 	int cq_jobs;
 	unsigned long flags;
+	get_online_cpus_atomic();
 	cpu_id = find_next_online_cpu(pool);
@@ -720,6 +722,7 @@  static void queue_comp_task(struct ehca_cq *__cq)
 		BUG_ON(!cct || !thread);
 	__queue_comp_task(__cq, cct, thread);
+	put_online_cpus_atomic();
 static void run_comp_task(struct ehca_cpu_comp_task *cct)
@@ -759,6 +762,7 @@  static void comp_task_park(unsigned int cpu)
 	list_splice_init(&cct->cq_list, &list);
+	get_online_cpus_atomic();
 	cpu = find_next_online_cpu(pool);
 	target = per_cpu_ptr(pool->cpu_comp_tasks, cpu);
 	thread = *per_cpu_ptr(pool->cpu_comp_threads, cpu);
@@ -768,6 +772,7 @@  static void comp_task_park(unsigned int cpu)
 		__queue_comp_task(cq, target, thread);
+	put_online_cpus_atomic();
 static void comp_task_stop(unsigned int cpu, bool online)