Date: Fri, 3 Oct 2008 13:56:30 -0600 (MDT) From: Scott Long <scottl@samsco.org> To: Jack Vogel <jfvogel@gmail.com> Cc: "freebsd-net@freebsd.org" <freebsd-net@FreeBSD.org>, Jeff Roberson <jroberson@jroberson.net>, Kip Macy <kmacy@FreeBSD.org>, John Baldwin <jhb@yahoo-inc.com> Subject: Re: potential nasty bug in igb and ixgbe Message-ID: <20081003135625.C39726@pooker.samsco.org> In-Reply-To: <2a41acea0810011516u77ca05b1k2df527e453dfe392@mail.gmail.com> References: <2a41acea0810011516u77ca05b1k2df527e453dfe392@mail.gmail.com>
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I'll bite. Scott On Wed, 1 Oct 2008, Jack Vogel wrote: > Jeff Roberson uncovered an issue that might be behind any number of > possible problems. > > Our newer hardware (meaning those supported by the igb and ixgbe > drivers) overwrites the buffer address in the RX > descriptor with a variety of data in support of advanced features (see > the relevant header files for details). > > However, in the rxeof code, if you fail to get a new mbuf, and hence, > will discard, the descriptor is being left in the wb form, > meaning that the address is jibberish for the next time the engine > uses that descriptor. > > I am modifying get_buf so that it fixes the address in the descriptor > when this happens. I know when my test group has had > the igb driver under heavy load they have had some panics, right now > I'm not sure if this has been at the root of those or not. > > If you want to see how I'm changing the code just speak up :) And > thanks for finding this Jeff. > > Jack >
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