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: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Alexander Duyck <alexander.h.duyck@xxxxxxxxx>
Cc: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Cc: Ben Hutchings <bhutchings@xxxxxxxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
---
net/core/dev.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index faebb39..1530633 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3175,7 +3175,7 @@ int netif_rx(struct sk_buff *skb)
struct rps_dev_flow voidflow, *rflow = &voidflow;
int cpu;
- preempt_disable();
+ get_online_cpus_atomic();
rcu_read_lock();
cpu = get_rps_cpu(skb->dev, skb, &rflow);
@@ -3185,7 +3185,7 @@ int netif_rx(struct sk_buff *skb)
ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
rcu_read_unlock();
- preempt_enable();
+ put_online_cpus_atomic();
} else
#endif
{
@@ -3604,6 +3604,7 @@ int netif_receive_skb(struct sk_buff *skb)
struct rps_dev_flow voidflow, *rflow = &voidflow;
int cpu, ret;
+ get_online_cpus_atomic();
rcu_read_lock();
cpu = get_rps_cpu(skb->dev, skb, &rflow);
@@ -3611,9 +3612,11 @@ int netif_receive_skb(struct sk_buff *skb)
if (cpu >= 0) {
ret = enqueue_to_backlog(skb, cpu, &rflow->last_qtail);
rcu_read_unlock();
+ put_online_cpus_atomic();
return ret;
}
rcu_read_unlock();
+ put_online_cpus_atomic();
}
#endif
return __netif_receive_skb(skb);
@@ -3991,6 +3994,7 @@ static void net_rps_action_and_irq_enable(struct softnet_data *sd)
local_irq_enable();
/* Send pending IPI's to kick RPS processing on remote cpus. */
+ get_online_cpus_atomic();
while (remsd) {
struct softnet_data *next = remsd->rps_ipi_next;
@@ -3999,6 +4003,7 @@ static void net_rps_action_and_irq_enable(struct softnet_data *sd)
&remsd->csd, 0);
remsd = next;
}
+ put_online_cpus_atomic();
} else
#endif
local_irq_enable();
--
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