Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755195AbaFLAYn (ORCPT ); Wed, 11 Jun 2014 20:24:43 -0400 Received: from e23smtp07.au.ibm.com ([202.81.31.140]:37360 "EHLO e23smtp07.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754234AbaFLAYl (ORCPT ); Wed, 11 Jun 2014 20:24:41 -0400 Date: Thu, 12 Jun 2014 10:24:33 +1000 From: Gavin Shan To: Alex Williamson Cc: Bjorn Helgaas , Ben Hutchings , Gavin Shan , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" , Alex Williamson , Greg Kroah-Hartman , linux-pci Subject: Re: [PATCH 3.14 186/228] PCI: Wrong register used to check pending traffic Message-ID: <20140612002433.GA13157@shangw> Reply-To: Gavin Shan References: <20140604232347.966798903@linuxfoundation.org> <20140604232354.004988520@linuxfoundation.org> <1402196538.23860.24.camel@deadeye.wl.decadent.org.uk> <1402524464.14174.186.camel@ul30vt.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1402524464.14174.186.camel@ul30vt.home> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14061200-0260-0000-0000-0000051EB426 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 11, 2014 at 04:07:44PM -0600, Alex Williamson wrote: >On Wed, 2014-06-11 at 15:15 -0600, Bjorn Helgaas wrote: >> On Sat, Jun 7, 2014 at 9:02 PM, Ben Hutchings wrote: >> > On Wed, 2014-06-04 at 16:23 -0700, Greg Kroah-Hartman wrote: >> >> 3.14-stable review patch. If anyone has any objections, please let me know. >> >> >> >> ------------------ >> >> >> >> From: Gavin Shan >> >> >> >> commit d0b4cc4e32705ff00d90d32da7783c266c702c04 upstream. >> >> >> >> The incorrect register offset is passed to pci_wait_for_pending(), which is >> >> caused by commit 157e876ffe ("PCI: Add pci_wait_for_pending() (refactor >> >> pci_wait_for_pending_transaction())"). >> >> >> >> Fixes: 157e876ffe ("PCI: Add pci_wait_for_pending() (refactor pci_wait_for_pending_transaction()) >> >> Signed-off-by: Gavin Shan >> >> Signed-off-by: Bjorn Helgaas >> >> Acked-by: Alex Williamson >> >> Signed-off-by: Greg Kroah-Hartman >> >> >> >> --- >> >> drivers/pci/pci.c | 5 +++-- >> >> 1 file changed, 3 insertions(+), 2 deletions(-) >> >> >> >> --- a/drivers/pci/pci.c >> >> +++ b/drivers/pci/pci.c >> >> @@ -3043,7 +3043,8 @@ int pci_wait_for_pending_transaction(str >> >> if (!pci_is_pcie(dev)) >> >> return 1; >> >> >> >> - return pci_wait_for_pending(dev, PCI_EXP_DEVSTA, PCI_EXP_DEVSTA_TRPND); >> >> + return pci_wait_for_pending(dev, pci_pcie_cap(dev) + PCI_EXP_DEVSTA, >> >> + PCI_EXP_DEVSTA_TRPND); >> >> } >> >> EXPORT_SYMBOL(pci_wait_for_pending_transaction); >> >> >> >> @@ -3085,7 +3086,7 @@ static int pci_af_flr(struct pci_dev *de >> >> return 0; >> >> >> >> /* Wait for Transaction Pending bit clean */ >> >> - if (pci_wait_for_pending(dev, PCI_AF_STATUS, PCI_AF_STATUS_TP)) >> >> + if (pci_wait_for_pending(dev, pos + PCI_AF_STATUS, PCI_AF_STATUS_TP)) >> >> goto clear; >> >> >> >> dev_err(&dev->dev, "transaction is not cleared; " >> > >> > This still seems to be broken because pci_wait_for_pending() does >> > pci_read_config_word() but PCI_AF_STATUS is not word-aligned. >> >> I agree; this does seem broken. I think pci_read_config_word() will >> return PCIBIOS_BAD_REGISTER_NUMBER without updating the value >> returned, so I think we'll test garbage from the stack. >> >> What do you think, Alex? > >Yep, looks broken. The simple fix would be to pass the AF control >offset instead of status, shift the mask, and maybe add a BUG_ON(pos & >1) to pci_read_config_word() to better enforce it. Alternatively we >could make the function take a width and use an appropriate accessor for >the size. I'm inclined to double-check the current users and take the >first option unless anyone objects. Thanks, > Hrm, I didn't notice that PCI_AF_STATUS isn't word-aligned. I agree with Alex to just use PCI_AF_CTRL with shifted PCI_AF_STATUS_TP. If we're going to add BUG_ON() for pci_read_config_word(), we have to add that for other accessors (dword, user_word, user_dword, bus_word, bus_dword). I guess we just need the first part here. Bjorn/Alex, please let me know if I need come up with a followup fix for this, or Alex can handle it. Thanks, Gavin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/