Re: [PATCH 2.6.18-rc4] aoe [04/13]: zero copy write 1 of 2
From: Ed L. Cashin
Date: Tue Aug 22 2006 - 18:48:47 EST
On Sat, Aug 19, 2006 at 11:18:12AM +0100, Alan Cox wrote:
> Ar Gwe, 2006-08-18 am 13:39 -0400, ysgrifennodd Ed L. Cashin:
> > Signed-off-by: "Ed L. Cashin" <ecashin@xxxxxxxxxx>
>
> > + skb->len = sizeof *h + sizeof *ah;
> > + memset(h, 0, skb->len);
>
> Never play with skb->len directly. Use skb_put/skb_trim
These are skbs pre-allocated by the aoe driver that will always have
enough room to accomodate this much data, and we are really setting
the packet header length.
To use skb_put here seems awkward. We'd have to do things like shown
below throughout the driver instead of just setting the length. Is
that what you'd like to see?
diff -upr 2.6.18-rc4-orig/drivers/block/aoe/aoecmd.c 2.6.18-rc4-aoe/drivers/block/aoe/aoecmd.c
--- 2.6.18-rc4-orig/drivers/block/aoe/aoecmd.c 2006-08-22 12:48:18.000000000 -0400
+++ 2.6.18-rc4-aoe/drivers/block/aoe/aoecmd.c 2006-08-22 17:03:23.000000000 -0400
@@ -314,7 +315,9 @@ rexmit(struct aoedev *d, struct frame *f
if (ah->aflags & AOEAFL_WRITE) {
skb_fill_page_desc(skb, 0, virt_to_page(f->bufaddr),
offset_in_page(f->bufaddr), DEFAULTBCNT);
- skb->len = sizeof *h + sizeof *ah + DEFAULTBCNT;
+ skb->data_len = 0;
+ skb_trim(skb, 0);
+ skb_put(skb, sizeof *h + sizeof *ah + DEFAULTBCNT);
skb->data_len = DEFAULTBCNT;
}
if (++d->lostjumbo > (d->nframes << 1))
--
Ed L Cashin <ecashin@xxxxxxxxxx>
-
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