On Thu, Apr 26, 2007 at 01:47:36PM -0400, Neil Horman wrote: > On Tue, Apr 24, 2007 at 12:43:20PM -0400, Jeff Garzik wrote: > > Neil Horman wrote: > > >Hey there- > > > The sis900 driver appears to have a bug in which the receive routine > > >passes the skbuff holding the received frame to the network stack before > > >refilling the buffer in the rx ring. If a new skbuff cannot be allocated, > > >the > > >driver simply leaves a hole in the rx ring, which causes the driver to stop > > >receiving frames and become non-recoverable without an rmmod/insmod > > >according to > > >reporters. This patch reverses that order, attempting to allocate a > > >replacement > > >buffer first, and receiving the new frame only if one can be allocated. > > >If no > > >skbuff can be allocated, the current skbuf in the rx ring is recycled, > > >dropping > > >the current frame, but keeping the NIC operational. > > > > > >Thanks & Regards > > >Neil > > > > > > Just found a hole in my last patch. It was reported to me that shortly after > we > integrated this patch. The report was of an oops that took place inside of > netif_rx when using the sis900 driver. Looking at my origional patch I noted > that there was a spot between the new skb_alloc and the refill_rx_ring label > where skb got reassigned to the pointer currently held in the rx_ring for the > purposes of receiveing the frame. The result of this is however that the > buffer > that gets passed to netif_rx (if it is called), then gets placed right back > into > the rx_ring. So if you receive frames fast enough the skb being processed by > the network stack can get corrupted. The reporter is testing out the fix I've > written for this below (I'm not near my hardware at the moment to test > myself), > but I wanted to post it for review ASAP. I'll post test results when I hear > them, but I think this is a pretty straightforward fix. It just uses a > separate > pointer to do the rx operation, so that we don't improperly reassign the > pointer > that we use to refill the rx ring. > > Thanks & Regards > Neil > Test results are back and appear successful. Neil
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