Messages in this thread | | | From | Rusty Russell <> | Subject | Re: [PATCH v2 1/4] Defer skb allocation -- add destroy buffers function for virtio | Date | Wed, 16 Dec 2009 09:06:12 +1030 |
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On Tue, 15 Dec 2009 06:52:53 am Michael S. Tsirkin wrote: > On Mon, Dec 14, 2009 at 12:08:05PM -0800, Shirley Ma wrote: > > Hello Michael, > > > > I agree with the comments (will have two patches instead of 4 based on > > Rusty's comments) except below one. > > > > On Sun, 2009-12-13 at 12:26 +0200, Michael S. Tsirkin wrote: > > > That said - do we have to use a callback? > > > I think destroy_buf which returns data pointer, > > > and which we call repeatedly until we get NULL > > > or error, would be an a better, more flexible API. > > > This is not critical though. > > > > The reason to use this is because in virtio_net remove, it has > > BUG_ON(vi->num != 0), which will be consistent with small skb packet. If > > we use NULL, error then we lose the track for vi->num, since we don't > > know how many buffers have been passed to ULPs or still unused. > > > > Thanks > > Shirley > > I dont insist, but my idea was > > for (;;) { > b = vq->destroy(vq); > if (!b) > break; > --vi->num; > put_page(b); > }
In this case it should be called "get_unused_buf" or something. But I like Shirley's approach here; destroy (with callback) accurately reflects the only time this can be validly used.
Cheers, Rusty.
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