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From: Herbert Xu <herbert@gondor.apana.org.au>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>,
	virtualization <virtualization@lists.osdl.org>,
	jgarzik <jgarzik@pobox.com>
Subject: Re: [PATCH 5/8] lguest: trivial guest network driver
Date: Tue, 13 Feb 2007 02:55:53 +1100	[thread overview]
Message-ID: <20070212155553.GA15627@gondor.apana.org.au> (raw)
In-Reply-To: <1171252321.10409.36.camel@localhost.localdomain>

On Mon, Feb 12, 2007 at 02:52:01PM +1100, Rusty Russell wrote:
>
> +static void skb_to_dma(const struct sk_buff *skb, unsigned int len,
> +		       struct lguest_dma *dma)
> +{
> +	unsigned int i, seg;
> +
> +	for (i = seg = 0; i < len; seg++, i += rest_of_page(skb->data + i)) {
> +		dma->addr[seg] = virt_to_phys(skb->data + i);
> +		dma->len[seg] = min((unsigned)(len - i),
> +				    rest_of_page(skb->data + i));
> +	}
> +	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++, seg++) {
> +		const skb_frag_t *f = &skb_shinfo(skb)->frags[i];
> +		/* Should not happen with MTU less than 64k - 2 * PAGE_SIZE. */
> +		if (seg == LGUEST_MAX_DMA_SECTIONS) {
> +			printk("Woah dude!  Megapacket!\n");
> +			break;
> +		}
> +		dma->addr[seg] = page_to_phys(f->page) + f->page_offset;
> +		dma->len[seg] = f->size;
> +	}

The length field from the skb covers the fragmented parts as well.
So you don't want to use it as the boundary for the loop over the
skb header data.  As it is, if the skb has fragments, the first
loop will try to read them off the header.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

  parent reply	other threads:[~2007-02-12 15:56 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-12  3:32 [PATCH 1/7] cleanup: paravirt unhandled fallthrough Rusty Russell
2007-02-12  3:33 ` [PATCH 2/7] cleanup: Initialize esp0 properly all the time Rusty Russell
2007-02-12  3:34   ` [PATCH 3/7] cleanup: Make hvc_console.c compile on non-PowerPC Rusty Russell
2007-02-12  3:35     ` [PATCH 4/7] cleanup: Move mce_disabled to asm/mce.h Rusty Russell
2007-02-12  3:36       ` [PATCH 5/7] cleanup: Rename cpu_gdt_descr and remove extern declaration from smpboot.c Rusty Russell
2007-02-12  3:37         ` [PATCH 6/7] cleanup: Remove extern declaration from mm/discontig.c, put in header Rusty Russell
2007-02-12  3:39           ` [PATCH 7/7] cleanup: make disable_acpi() valid w/o CONFIG_ACPI Rusty Russell
2007-02-12  3:41             ` [PATCH 1/2] lguest preparation: EXPORT_SYMBOL_GPL 5 functions Rusty Russell
2007-02-12  3:42               ` [PATCH 2/2] lguest preparation: expose futex infrastructure: get_futex_key, get_key_refs and drop_key_refs Rusty Russell
2007-02-12  3:44                 ` [PATCH 1/8] lguest: Kconfig and headers Rusty Russell
2007-02-12  3:46                   ` [PATCH 2/8] lguest: the host code (lg.ko) Rusty Russell
2007-02-12  3:48                     ` [PATCH 3/8] lguest: Guest code Rusty Russell
2007-02-12  3:50                       ` [PATCH 4/8] lguest: Makefile Rusty Russell
2007-02-12  3:52                         ` [PATCH 5/8] lguest: trivial guest network driver Rusty Russell
2007-02-12  3:53                           ` [PATCH 6/8] lguest: trivial guest console driver Rusty Russell
2007-02-12  3:54                             ` [PATCH 7/8] lguest: trivial guest block driver Rusty Russell
2007-02-12  3:55                               ` [PATCH 8/8] lguest: documentatation and example launcher Rusty Russell
2007-02-12  4:43                               ` [PATCH 7/8] lguest: trivial guest block driver Jens Axboe
2007-02-12  5:27                                 ` Rusty Russell
2007-02-12  5:32                                   ` Jens Axboe
2007-02-12  5:33                                     ` Jens Axboe
2007-02-12  7:09                                     ` Rusty Russell
2007-02-12 15:01                                       ` Jens Axboe
2007-02-13  0:25                                         ` Rusty Russell
2007-02-13  0:44                                           ` Jens Axboe
2007-02-12 15:55                           ` Herbert Xu [this message]
2007-02-13  2:15                             ` [PATCH 5/8] lguest: trivial guest network driver Rusty Russell
2007-02-13 14:06                               ` Herbert Xu
2007-02-14  4:47                                 ` Rusty Russell
2007-02-14 13:57                                   ` Herbert Xu
2007-02-14 23:00                                     ` Rusty Russell
2007-02-12 16:02                   ` [PATCH 1/8] lguest: Kconfig and headers James Morris
2007-02-13  5:09             ` [PATCH 7/7] cleanup: make disable_acpi() valid w/o CONFIG_ACPI Len Brown
2007-02-12  9:16         ` [PATCH 5/7] cleanup: Rename cpu_gdt_descr and remove extern declaration from smpboot.c Zachary Amsden

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