Messages in this thread | | | Date | Tue, 31 Dec 2002 10:31:51 +0100 | From | Manfred Spraul <> | Subject | Re: question on context of kfree_skb() |
| |
Oliver Neukum wrote:
>Am Montag, 30. Dezember 2002 23:32 schrieb Manfred Spraul: > > >>Mulix wrote: >> >> >>>dev_kfree_skb_any() should be called when you could be either >>>executing in interrupt context or not. >>> >>> >>dev_kfree_skb_any() can misdetect the context: You must not use the >>function if you hold an irq spinlock and you might be running from BH or >>process context. >> >> > >What then shall be used under these circumstances ? >Could you perhaps summarise the issue ? > > When a packet is freed, the upper layers must be notified, for example a user space process could be waiting for socket buffer space. This can happen either immediately, or in the next softirq.
dev_kfree_skb_irq() is always ok, although slower than the other functions. The packet is unconditionally queued and processed later. dev_kfree_skb_any() tries to optimize it a bit: If it thinks that it's save to process it now, then the packet is processed immediately. The autodetection is usually correct, except for the special case I mentioned. Drivers must work around that. dev_kfree_skb() always processes the packet immediately. Only permitted from bottom half context or from process context.
-- Manfred
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |