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net: do not provide hard irq safety for sd->defer_lock

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kfree_skb() can be called from hard irq handlers,
but skb_attempt_defer_free() is meant to be used
from process or BH contexts, and skb_defer_free_flush()
is meant to be called from BH contexts.

Not having to mask hard irq can save some cycles.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2023-04-21 09:43:54 +00:00 committed by David S. Miller
parent e8e1ce8454
commit 931e93bdf8
2 changed files with 4 additions and 5 deletions
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4
net/core/dev.c
View File

@ -6632,11 +6632,11 @@ static void skb_defer_free_flush(struct softnet_data *sd)
if (!READ_ONCE(sd->defer_list))
return;
spin_lock_irq(&sd->defer_lock);
spin_lock(&sd->defer_lock);
skb = sd->defer_list;
sd->defer_list = NULL;
sd->defer_count = 0;
spin_unlock_irq(&sd->defer_lock);
spin_unlock(&sd->defer_lock);
while (skb != NULL) {
next = skb->next;

5
net/core/skbuff.c
View File

@ -6870,7 +6870,6 @@ void skb_attempt_defer_free(struct sk_buff *skb)
{
int cpu = skb->alloc_cpu;
struct softnet_data *sd;
unsigned long flags;
unsigned int defer_max;
bool kick;
@ -6889,7 +6888,7 @@ nodefer: __kfree_skb(skb);
if (READ_ONCE(sd->defer_count) >= defer_max)
goto nodefer;
spin_lock_irqsave(&sd->defer_lock, flags);
spin_lock_bh(&sd->defer_lock);
/* Send an IPI every time queue reaches half capacity. */
kick = sd->defer_count == (defer_max >> 1);
/* Paired with the READ_ONCE() few lines above */
@ -6898,7 +6897,7 @@ nodefer: __kfree_skb(skb);
skb->next = sd->defer_list;
/* Paired with READ_ONCE() in skb_defer_free_flush() */
WRITE_ONCE(sd->defer_list, skb);
spin_unlock_irqrestore(&sd->defer_lock, flags);
spin_unlock_bh(&sd->defer_lock);
/* Make sure to trigger NET_RX_SOFTIRQ on the remote CPU
* if we are unlucky enough (this seems very unlikely).