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authorEric Dumazet <edumazet@google.com>2015-01-15 17:04:22 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-02-26 17:50:10 -0800
commit64d76f569ae7f966b9e5fa26fd6d822df8d2f96f (patch)
treea338a68d94f878462736859ec851a788ec289525 /net/core/dev.c
parentada98740b7198b58cd7882c49dfbd4d3047b911e (diff)
downloadlinux-linaro-stable-64d76f569ae7f966b9e5fa26fd6d822df8d2f96f.tar.gz
net: rps: fix cpu unplug
[ Upstream commit ac64da0b83d82abe62f78b3d0e21cca31aea24fa ] softnet_data.input_pkt_queue is protected by a spinlock that we must hold when transferring packets from victim queue to an active one. This is because other cpus could still be trying to enqueue packets into victim queue. A second problem is that when we transfert the NAPI poll_list from victim to current cpu, we absolutely need to special case the percpu backlog, because we do not want to add complex locking to protect process_queue : Only owner cpu is allowed to manipulate it, unless cpu is offline. Based on initial patch from Prasad Sodagudi & Subash Abhinov Kasiviswanathan. This version is better because we do not slow down packet processing, only make migration safer. Reported-by: Prasad Sodagudi <psodagud@codeaurora.org> Reported-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Tom Herbert <therbert@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/core/dev.c')
-rw-r--r--net/core/dev.c20
1 files changed, 15 insertions, 5 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index 86bb9cc81f02..4ed77d7245c0 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6812,10 +6812,20 @@ static int dev_cpu_callback(struct notifier_block *nfb,
oldsd->output_queue = NULL;
oldsd->output_queue_tailp = &oldsd->output_queue;
}
- /* Append NAPI poll list from offline CPU. */
- if (!list_empty(&oldsd->poll_list)) {
- list_splice_init(&oldsd->poll_list, &sd->poll_list);
- raise_softirq_irqoff(NET_RX_SOFTIRQ);
+ /* Append NAPI poll list from offline CPU, with one exception :
+ * process_backlog() must be called by cpu owning percpu backlog.
+ * We properly handle process_queue & input_pkt_queue later.
+ */
+ while (!list_empty(&oldsd->poll_list)) {
+ struct napi_struct *napi = list_first_entry(&oldsd->poll_list,
+ struct napi_struct,
+ poll_list);
+
+ list_del_init(&napi->poll_list);
+ if (napi->poll == process_backlog)
+ napi->state = 0;
+ else
+ ____napi_schedule(sd, napi);
}
raise_softirq_irqoff(NET_TX_SOFTIRQ);
@@ -6826,7 +6836,7 @@ static int dev_cpu_callback(struct notifier_block *nfb,
netif_rx_internal(skb);
input_queue_head_incr(oldsd);
}
- while ((skb = __skb_dequeue(&oldsd->input_pkt_queue))) {
+ while ((skb = skb_dequeue(&oldsd->input_pkt_queue))) {
netif_rx_internal(skb);
input_queue_head_incr(oldsd);
}