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Subject[PATCH v6 24/46] [SCSI] fcoe: Use get/put_online_cpus_atomic() to prevent CPU offline
Date
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: Robert Love <robert.w.love@intel.com>
Cc: "James E.J. Bottomley" <JBottomley@parallels.com>
Cc: devel@open-fcoe.org
Cc: linux-scsi@vger.kernel.org
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
---

drivers/scsi/fcoe/fcoe.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
index 666b7ac..c971a17 100644
--- a/drivers/scsi/fcoe/fcoe.c
+++ b/drivers/scsi/fcoe/fcoe.c
@@ -1475,6 +1475,7 @@ static int fcoe_rcv(struct sk_buff *skb, struct net_device *netdev,
* was originated, otherwise select cpu using rx exchange id
* or fcoe_select_cpu().
*/
+ get_online_cpus_atomic();
if (ntoh24(fh->fh_f_ctl) & FC_FC_EX_CTX)
cpu = ntohs(fh->fh_ox_id) & fc_cpu_mask;
else {
@@ -1484,8 +1485,10 @@ static int fcoe_rcv(struct sk_buff *skb, struct net_device *netdev,
cpu = ntohs(fh->fh_rx_id) & fc_cpu_mask;
}

- if (cpu >= nr_cpu_ids)
+ if (cpu >= nr_cpu_ids) {
+ put_online_cpus_atomic();
goto err;
+ }

fps = &per_cpu(fcoe_percpu, cpu);
spin_lock(&fps->fcoe_rx_list.lock);
@@ -1505,6 +1508,7 @@ static int fcoe_rcv(struct sk_buff *skb, struct net_device *netdev,
spin_lock(&fps->fcoe_rx_list.lock);
if (!fps->thread) {
spin_unlock(&fps->fcoe_rx_list.lock);
+ put_online_cpus_atomic();
goto err;
}
}
@@ -1526,6 +1530,7 @@ static int fcoe_rcv(struct sk_buff *skb, struct net_device *netdev,
if (fps->thread->state == TASK_INTERRUPTIBLE)
wake_up_process(fps->thread);
spin_unlock(&fps->fcoe_rx_list.lock);
+ put_online_cpus_atomic();

return 0;
err:


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