From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH 0/10] DMA-API debugging facility Date: Fri, 21 Nov 2008 17:40:41 +0100 Message-ID: <20081121164041.GA1386@amd.com> References: <1227284770-19215-1-git-send-email-joerg.roedel@amd.com> <20081121163717.GA733@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: Ingo Molnar , Thomas Gleixner , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, iommu@lists.linux-foundation.org To: Ingo Molnar Return-path: Content-Disposition: inline In-Reply-To: <20081121163717.GA733@elte.hu> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Fri, Nov 21, 2008 at 05:37:17PM +0100, Ingo Molnar wrote: > > * Joerg Roedel wrote: > > > Hi, > > > > this patchset introduces code to debug drivers usage of the DMA-API. > > Tests with hardware IOMMUs have shown several bugs in drivers > > regarding the usage of that API. Problems were found especially in > > network card drivers. > > > > These bugs often don't show up or have any negative impact if there > > is no hardware IOMMU in use in the system. But with an hardware > > IOMMU these bugs turn the hardware unusable or, in the worst case, > > cause data corruption on devices which are managed by other (good) > > drivers. > > > > With the code these patches introduce driver developers can find > > several bugs of misusing the DMA-API in their drivers. But be aware, > > it can not find all possible bugs. If it finds a problem it prints > > out messages like > > > > tg3 0000:08:04.0: PCI-DMA: device driver tries to free DMA memory it > > has not allocated [device address=0x000000042f0f3ae7] [size=48 > > bytes] > > > > Pid: 6285, comm: bash Not tainted 2.6.28-rc5-00176-g6ae6379-dirty #6 > > Call Trace: > > [] check_unmap+0x52/0x1ce > > [] debug_unmap_single+0x61/0xa4 > > [] skb_dma_unmap+0xf2/0x10c > > [] tg3_poll+0xe8/0x822 > > [] mix_pool_bytes_extract+0x5c/0x155 > > [] net_rx_action+0x9d/0x170 > > very nice! I like this approach - and have a few comments on some > details - will post them as a reply to the patchs. Cool. Thank you. Joerg -- | AMD Saxony Limited Liability Company & Co. KG Operating | Wilschdorfer Landstr. 101, 01109 Dresden, Germany System | Register Court Dresden: HRA 4896 Research | General Partner authorized to represent: Center | AMD Saxony LLC (Wilmington, Delaware, US) | General Manager of AMD Saxony LLC: Dr. Hans-R. Deppe, Thomas McCoy