* [PATCH] Fix locking in flush_backlog
@ 2010-03-23 6:04 Tom Herbert
2010-03-23 6:29 ` Eric Dumazet
0 siblings, 1 reply; 4+ messages in thread
From: Tom Herbert @ 2010-03-23 6:04 UTC (permalink / raw)
To: davem, netdev
Need to take spinlocks when dequeuing from input_pkt_queue in
flush_backlog. Also, with the spinlock the backlog queues can
be flushed directly from netdev_run_todo.
Signed-off-by: Tom Herbert <therbert@google.com>
---
diff --git a/net/core/dev.c b/net/core/dev.c
index a03aab4..e7db656 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2765,20 +2765,6 @@ int netif_receive_skb(struct sk_buff *skb)
}
EXPORT_SYMBOL(netif_receive_skb);
-/* Network device is going away, flush any packets still pending */
-static void flush_backlog(void *arg)
-{
- struct net_device *dev = arg;
- struct softnet_data *queue = &__get_cpu_var(softnet_data);
- struct sk_buff *skb, *tmp;
-
- skb_queue_walk_safe(&queue->input_pkt_queue, skb, tmp)
- if (skb->dev == dev) {
- __skb_unlink(skb, &queue->input_pkt_queue);
- kfree_skb(skb);
- }
-}
-
static int napi_gro_complete(struct sk_buff *skb)
{
struct packet_type *ptype;
@@ -5545,6 +5531,7 @@ void netdev_run_todo(void)
while (!list_empty(&list)) {
struct net_device *dev
= list_first_entry(&list, struct net_device, todo_list);
+ int i;
list_del(&dev->todo_list);
if (unlikely(dev->reg_state != NETREG_UNREGISTERING)) {
@@ -5556,7 +5543,22 @@ void netdev_run_todo(void)
dev->reg_state = NETREG_UNREGISTERED;
- on_each_cpu(flush_backlog, dev, 1);
+ /* Flush backlog queues of any pending packets */
+ for_each_online_cpu(i) {
+ struct softnet_data *queue = &per_cpu(softnet_data, i);
+ struct sk_buff *skb, *tmp;
+ unsigned long flags;
+
+ spin_lock_irqsave(&queue->input_pkt_queue.lock, flags);
+ skb_queue_walk_safe(&queue->input_pkt_queue, skb, tmp)
+ if (skb->dev == dev) {
+ __skb_unlink(skb,
+ &queue->input_pkt_queue);
+ kfree_skb(skb);
+ }
+ spin_unlock_irqrestore(&queue->input_pkt_queue.lock,
+ flags);
+ }
netdev_wait_allrefs(dev);
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] Fix locking in flush_backlog
2010-03-23 6:04 [PATCH] Fix locking in flush_backlog Tom Herbert
@ 2010-03-23 6:29 ` Eric Dumazet
2010-03-23 15:56 ` Tom Herbert
0 siblings, 1 reply; 4+ messages in thread
From: Eric Dumazet @ 2010-03-23 6:29 UTC (permalink / raw)
To: Tom Herbert; +Cc: davem, netdev
Le lundi 22 mars 2010 à 23:04 -0700, Tom Herbert a écrit :
> Need to take spinlocks when dequeuing from input_pkt_queue in
> flush_backlog. Also, with the spinlock the backlog queues can
> be flushed directly from netdev_run_todo.
>
> Signed-off-by: Tom Herbert <therbert@google.com>
> ---
> diff --git a/net/core/dev.c b/net/core/dev.c
> index a03aab4..e7db656 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -2765,20 +2765,6 @@ int netif_receive_skb(struct sk_buff *skb)
> }
> EXPORT_SYMBOL(netif_receive_skb);
>
> -/* Network device is going away, flush any packets still pending */
> -static void flush_backlog(void *arg)
> -{
> - struct net_device *dev = arg;
> - struct softnet_data *queue = &__get_cpu_var(softnet_data);
> - struct sk_buff *skb, *tmp;
> -
> - skb_queue_walk_safe(&queue->input_pkt_queue, skb, tmp)
> - if (skb->dev == dev) {
> - __skb_unlink(skb, &queue->input_pkt_queue);
> - kfree_skb(skb);
> - }
> -}
> -
> static int napi_gro_complete(struct sk_buff *skb)
> {
> struct packet_type *ptype;
> @@ -5545,6 +5531,7 @@ void netdev_run_todo(void)
> while (!list_empty(&list)) {
> struct net_device *dev
> = list_first_entry(&list, struct net_device, todo_list);
> + int i;
> list_del(&dev->todo_list);
>
> if (unlikely(dev->reg_state != NETREG_UNREGISTERING)) {
> @@ -5556,7 +5543,22 @@ void netdev_run_todo(void)
>
> dev->reg_state = NETREG_UNREGISTERED;
>
> - on_each_cpu(flush_backlog, dev, 1);
> + /* Flush backlog queues of any pending packets */
> + for_each_online_cpu(i) {
> + struct softnet_data *queue = &per_cpu(softnet_data, i);
> + struct sk_buff *skb, *tmp;
> + unsigned long flags;
> +
> + spin_lock_irqsave(&queue->input_pkt_queue.lock, flags);
> + skb_queue_walk_safe(&queue->input_pkt_queue, skb, tmp)
> + if (skb->dev == dev) {
> + __skb_unlink(skb,
> + &queue->input_pkt_queue);
> + kfree_skb(skb);
> + }
> + spin_unlock_irqrestore(&queue->input_pkt_queue.lock,
> + flags);
> + }
>
> netdev_wait_allrefs(dev);
>
OK (this is a patch for net-next-2.6)
Could you please keep the function, to ease netdev_run_todo() review ?
Thanks
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] Fix locking in flush_backlog
2010-03-23 6:29 ` Eric Dumazet
@ 2010-03-23 15:56 ` Tom Herbert
2010-03-23 16:14 ` Eric Dumazet
0 siblings, 1 reply; 4+ messages in thread
From: Tom Herbert @ 2010-03-23 15:56 UTC (permalink / raw)
To: Eric Dumazet; +Cc: davem, netdev
On Mon, Mar 22, 2010 at 11:29 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> Le lundi 22 mars 2010 à 23:04 -0700, Tom Herbert a écrit :
>> Need to take spinlocks when dequeuing from input_pkt_queue in
>> flush_backlog. Also, with the spinlock the backlog queues can
>> be flushed directly from netdev_run_todo.
>>
>> Signed-off-by: Tom Herbert <therbert@google.com>
>> ---
>> diff --git a/net/core/dev.c b/net/core/dev.c
>> index a03aab4..e7db656 100644
>> --- a/net/core/dev.c
>> +++ b/net/core/dev.c
>> @@ -2765,20 +2765,6 @@ int netif_receive_skb(struct sk_buff *skb)
>> }
>> EXPORT_SYMBOL(netif_receive_skb);
>>
>> -/* Network device is going away, flush any packets still pending */
>> -static void flush_backlog(void *arg)
>> -{
>> - struct net_device *dev = arg;
>> - struct softnet_data *queue = &__get_cpu_var(softnet_data);
>> - struct sk_buff *skb, *tmp;
>> -
>> - skb_queue_walk_safe(&queue->input_pkt_queue, skb, tmp)
>> - if (skb->dev == dev) {
>> - __skb_unlink(skb, &queue->input_pkt_queue);
>> - kfree_skb(skb);
>> - }
>> -}
>> -
>> static int napi_gro_complete(struct sk_buff *skb)
>> {
>> struct packet_type *ptype;
>> @@ -5545,6 +5531,7 @@ void netdev_run_todo(void)
>> while (!list_empty(&list)) {
>> struct net_device *dev
>> = list_first_entry(&list, struct net_device, todo_list);
>> + int i;
>> list_del(&dev->todo_list);
>>
>> if (unlikely(dev->reg_state != NETREG_UNREGISTERING)) {
>> @@ -5556,7 +5543,22 @@ void netdev_run_todo(void)
>>
>> dev->reg_state = NETREG_UNREGISTERED;
>>
>> - on_each_cpu(flush_backlog, dev, 1);
>> + /* Flush backlog queues of any pending packets */
>> + for_each_online_cpu(i) {
>> + struct softnet_data *queue = &per_cpu(softnet_data, i);
>> + struct sk_buff *skb, *tmp;
>> + unsigned long flags;
>> +
>> + spin_lock_irqsave(&queue->input_pkt_queue.lock, flags);
>> + skb_queue_walk_safe(&queue->input_pkt_queue, skb, tmp)
>> + if (skb->dev == dev) {
>> + __skb_unlink(skb,
>> + &queue->input_pkt_queue);
>> + kfree_skb(skb);
>> + }
>> + spin_unlock_irqrestore(&queue->input_pkt_queue.lock,
>> + flags);
>> + }
>>
>> netdev_wait_allrefs(dev);
>>
>
> OK (this is a patch for net-next-2.6)
>
> Could you please keep the function, to ease netdev_run_todo() review ?
>
Eric,
I'm not sure what you're asking. Do you just want to add spinlocks in
the flush_backlog function without changing the mechanism to call the
function on each CPU, or keep flush_backlog but call it from
netdev_run_todo for each queue?
Tom
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] Fix locking in flush_backlog
2010-03-23 15:56 ` Tom Herbert
@ 2010-03-23 16:14 ` Eric Dumazet
0 siblings, 0 replies; 4+ messages in thread
From: Eric Dumazet @ 2010-03-23 16:14 UTC (permalink / raw)
To: Tom Herbert; +Cc: davem, netdev
Le mardi 23 mars 2010 à 08:56 -0700, Tom Herbert a écrit :
> Eric,
>
> I'm not sure what you're asking. Do you just want to add spinlocks in
> the flush_backlog function without changing the mechanism to call the
> function on each CPU, or keep flush_backlog but call it from
> netdev_run_todo for each queue?
>
keep flush_backlog() so that its role is obvious and indentation level
not too big.
static void flush_backlog(int cpu)
{
struct softnet_data *queue = &per_cpu(softnet_data, cpu);
struct sk_buff *skb, *tmp;
unsigned long flags;
spin_lock_irqsave(&queue->input_pkt_queue.lock, flags);
skb_queue_walk_safe(&queue->input_pkt_queue, skb, tmp)
if (skb->dev == dev) {
__skb_unlink(skb, &queue->input_pkt_queue);
kfree_skb(skb);
}
spin_unlock_irqrestore(&queue->input_pkt_queue.lock, flags);
}
And call it from netdev_run_todo() :
for_each_online_cpu(i)
flush_backlog(i);
This adds two lines to netdev_run_todo() only.
Thanks
^ permalink raw reply [flat|nested] 4+ messages in thread
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2010-03-23 6:04 [PATCH] Fix locking in flush_backlog Tom Herbert
2010-03-23 6:29 ` Eric Dumazet
2010-03-23 15:56 ` Tom Herbert
2010-03-23 16:14 ` Eric Dumazet
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