Patchwork [v5,24/45] staging: octeon: Use get/put_online_cpus_atomic() to prevent CPU offline

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Submitter Srivatsa S. Bhat
Date Jan. 22, 2013, 7:39 a.m.
Message ID <20130122073928.13822.79334.stgit@srivatsabhat.in.ibm.com>
Download mbox | patch
Permalink /patch/214422/
State Not Applicable
Headers show

Comments

Srivatsa S. Bhat - Jan. 22, 2013, 7:39 a.m.
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: David Daney <david.daney@cavium.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
---

 drivers/staging/octeon/ethernet-rx.c |    3 +++
 1 file changed, 3 insertions(+)

Patch

diff --git a/drivers/staging/octeon/ethernet-rx.c b/drivers/staging/octeon/ethernet-rx.c
index 34afc16..8588b4d 100644
--- a/drivers/staging/octeon/ethernet-rx.c
+++ b/drivers/staging/octeon/ethernet-rx.c
@@ -36,6 +36,7 @@ 
 #include <linux/prefetch.h>
 #include <linux/ratelimit.h>
 #include <linux/smp.h>
+#include <linux/cpu.h>
 #include <linux/interrupt.h>
 #include <net/dst.h>
 #ifdef CONFIG_XFRM
@@ -97,6 +98,7 @@  static void cvm_oct_enable_one_cpu(void)
 		return;
 
 	/* ... if a CPU is available, Turn on NAPI polling for that CPU.  */
+	get_online_cpus_atomic();
 	for_each_online_cpu(cpu) {
 		if (!cpu_test_and_set(cpu, core_state.cpu_state)) {
 			v = smp_call_function_single(cpu, cvm_oct_enable_napi,
@@ -106,6 +108,7 @@  static void cvm_oct_enable_one_cpu(void)
 			break;
 		}
 	}
+	put_online_cpus_atomic();
 }
 
 static void cvm_oct_no_more_work(void)