Message ID | 1430183690-24198-1-git-send-email-kys@microsoft.com |
---|---|
State | Changes Requested, archived |
Delegated to: | David Miller |
Headers | show |
From: "K. Y. Srinivasan" <kys@microsoft.com> Date: Mon, 27 Apr 2015 18:14:50 -0700 > Commit commit b08cc79155fc26d0d112b1470d1ece5034651a4b eliminated memory > allocation in the packet send path. This commit introduced a bug since it > did not account for the case if the skb was cloned. Fix this bug by > using the pre-reserved head room only if the skb is not cloned. > > Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> We have generic infrastructure to do this, please try instead: err = skb_cow_head(skb, pkt_sz); this will take care of everything for you and you can get rid of all of this dynamic memory allocation etc. in this code path. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
> -----Original Message----- > From: devel [mailto:driverdev-devel-bounces@linuxdriverproject.org] On > Behalf Of K. Y. Srinivasan > Sent: Tuesday, April 28, 2015 9:15 > To: davem@davemloft.net; netdev@vger.kernel.org; linux- > kernel@vger.kernel.org; devel@linuxdriverproject.org; olaf@aepfle.de; > apw@canonical.com; jasowang@redhat.com > Subject: [PATCH net 1/1] hv_netvsc: Fix a bug in netvsc_start_xmit() > > Commit commit b08cc79155fc26d0d112b1470d1ece5034651a4b > eliminated memory > allocation in the packet send path. This commit introduced a bug since it > did not account for the case if the skb was cloned. Fix this bug by > using the pre-reserved head room only if the skb is not cloned. > > Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> > --- > drivers/net/hyperv/netvsc_drv.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/drivers/net/hyperv/netvsc_drv.c > b/drivers/net/hyperv/netvsc_drv.c > index a3a9d38..7eb0251 100644 > --- a/drivers/net/hyperv/netvsc_drv.c > +++ b/drivers/net/hyperv/netvsc_drv.c > @@ -421,7 +421,7 @@ check_size: > > pkt_sz = sizeof(struct hv_netvsc_packet) + RNDIS_AND_PPI_SIZE; > > - if (head_room < pkt_sz) { > + if (skb->cloned || head_room < pkt_sz) { > packet = kmalloc(pkt_sz, GFP_ATOMIC); > if (!packet) { > /* out of memory, drop packet */ > -- Without the patch, the guest can panic due to memory corruption. I confirm the patch can fix the panic I saw. Tested-by: Dexuan Cui <decui@microsoft.com> Thanks, -- Dexuan -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
> -----Original Message----- > From: David Miller [mailto:davem@davemloft.net] > Sent: Monday, April 27, 2015 7:57 PM > To: KY Srinivasan > Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org; > devel@linuxdriverproject.org; olaf@aepfle.de; apw@canonical.com; > jasowang@redhat.com > Subject: Re: [PATCH net 1/1] hv_netvsc: Fix a bug in netvsc_start_xmit() > > From: "K. Y. Srinivasan" <kys@microsoft.com> > Date: Mon, 27 Apr 2015 18:14:50 -0700 > > > Commit commit b08cc79155fc26d0d112b1470d1ece5034651a4b eliminated > memory > > allocation in the packet send path. This commit introduced a bug since it > > did not account for the case if the skb was cloned. Fix this bug by > > using the pre-reserved head room only if the skb is not cloned. > > > > Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> > > We have generic infrastructure to do this, please try instead: > > err = skb_cow_head(skb, pkt_sz); > > this will take care of everything for you and you can get rid > of all of this dynamic memory allocation etc. in this code > path. Thanks David; I will resubmit this patch. Regards, K. Y -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hello. On 04/28/2015 04:14 AM, K. Y. Srinivasan wrote: > Commit commit b08cc79155fc26d0d112b1470d1ece5034651a4b eliminated memory One "commit" is enough. :-) And please also specify that commit's summary in parens. > allocation in the packet send path. This commit introduced a bug since it > did not account for the case if the skb was cloned. Fix this bug by > using the pre-reserved head room only if the skb is not cloned. > Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> [...] WBR, Sergei -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
> -----Original Message----- > From: Sergei Shtylyov [mailto:sergei.shtylyov@cogentembedded.com] > Sent: Tuesday, April 28, 2015 11:27 AM > To: KY Srinivasan; davem@davemloft.net; netdev@vger.kernel.org; linux- > kernel@vger.kernel.org; devel@linuxdriverproject.org; olaf@aepfle.de; > apw@canonical.com; jasowang@redhat.com > Subject: Re: [PATCH net 1/1] hv_netvsc: Fix a bug in netvsc_start_xmit() > > Hello. > > On 04/28/2015 04:14 AM, K. Y. Srinivasan wrote: > > > Commit commit b08cc79155fc26d0d112b1470d1ece5034651a4b eliminated > memory > > One "commit" is enough. :-) > And please also specify that commit's summary in parens. > > > allocation in the packet send path. This commit introduced a bug since it > > did not account for the case if the skb was cloned. Fix this bug by > > using the pre-reserved head room only if the skb is not cloned. > > > Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> > > [...] > > WBR, Sergei Will do; thanks. K. Y -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c index a3a9d38..7eb0251 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -421,7 +421,7 @@ check_size: pkt_sz = sizeof(struct hv_netvsc_packet) + RNDIS_AND_PPI_SIZE; - if (head_room < pkt_sz) { + if (skb->cloned || head_room < pkt_sz) { packet = kmalloc(pkt_sz, GFP_ATOMIC); if (!packet) { /* out of memory, drop packet */
Commit commit b08cc79155fc26d0d112b1470d1ece5034651a4b eliminated memory allocation in the packet send path. This commit introduced a bug since it did not account for the case if the skb was cloned. Fix this bug by using the pre-reserved head room only if the skb is not cloned. Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> --- drivers/net/hyperv/netvsc_drv.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)