[PATCH v5 31/45] blackfin/smp: Use get/put_online_cpus_atomic() to prevent CPU offline

Srivatsa S. Bhat srivatsa.bhat at linux.vnet.ibm.com
Tue Jan 22 18:41:26 EST 2013

Once stop_machine() is gone from the CPU offline path, we won't be able to
depend on preempt_disable() or local_irq_disable() 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: Mike Frysinger <vapier at gentoo.org>
Cc: Bob Liu <lliubbo at gmail.com>
Cc: Steven Miao <realmz6 at gmail.com>
Cc: uclinux-dist-devel at blackfin.uclinux.org
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat at linux.vnet.ibm.com>

 arch/blackfin/mach-common/smp.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/blackfin/mach-common/smp.c b/arch/blackfin/mach-common/smp.c
index bb61ae4..6cc6d7a 100644
--- a/arch/blackfin/mach-common/smp.c
+++ b/arch/blackfin/mach-common/smp.c
@@ -194,6 +194,7 @@ void send_ipi(const struct cpumask *cpumask, enum ipi_message_type msg)
 	struct ipi_data *bfin_ipi_data;
 	unsigned long flags;
+	get_online_cpus_atomic();
 	for_each_cpu(cpu, cpumask) {
@@ -205,6 +206,7 @@ void send_ipi(const struct cpumask *cpumask, enum ipi_message_type msg)
+	put_online_cpus_atomic();
 void arch_send_call_function_single_ipi(int cpu)
@@ -238,13 +240,13 @@ void smp_send_stop(void)
 	cpumask_t callmap;
-	preempt_disable();
+	get_online_cpus_atomic();
 	cpumask_copy(&callmap, cpu_online_mask);
 	cpumask_clear_cpu(smp_processor_id(), &callmap);
 	if (!cpumask_empty(&callmap))
 		send_ipi(&callmap, BFIN_IPI_CPU_STOP);
-	preempt_enable();
+	put_online_cpus_atomic();

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