for_each_possible_cpu() with a cpu_online() + `thread' check possibly does
the job. But there is a tiny race: Say CPU5 is reported online but is
going down. And after fcoe_percpu_clean() saw that CPU5 is online it
decided to enqueue a packet. After dev_alloc_skb() returned a skb
that CPU is offline (or say the notifier destroyed the kthread). So we
would OOps because `thread' is NULL.
An alternative would be to lock the CPUs during our loop (so no CPU is
going away) and then we iterate over the online mask.
Cc: Vasu Dev <vasu.dev@xxxxxxxxx>
Cc: "James E.J. Bottomley" <JBottomley@xxxxxxxx>
Cc: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: fcoe-devel@xxxxxxxxxxxxx
Cc: linux-scsi@xxxxxxxxxxxxxxx
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
drivers/scsi/fcoe/fcoe.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
index 0efe7112fc1f..2b0d207f4b2b 100644
--- a/drivers/scsi/fcoe/fcoe.c
+++ b/drivers/scsi/fcoe/fcoe.c
@@ -2461,12 +2461,10 @@ static void fcoe_percpu_clean(struct fc_lport *lport)
struct sk_buff *skb;
unsigned int cpu;
- for_each_possible_cpu(cpu) {
+ get_online_cpus();
+ for_each_online_cpu(cpu) {
pp = &per_cpu(fcoe_percpu, cpu);
- if (!pp->thread || !cpu_online(cpu))
- continue;
-
skb = dev_alloc_skb(0);
if (!skb)
continue;
@@ -2481,6 +2479,7 @@ static void fcoe_percpu_clean(struct fc_lport *lport)
wait_for_completion(&fcoe_flush_completion);
}
+ put_online_cpus();
}
/**
--
2.7.0
--
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