From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AB8JxZr8gx7zYOgvZZjROYPgYksjqP/8jZqA+2a9KDuPphqCkmsjuAI2h1lHJLhTGuHGS4D9wZIQ ARC-Seal: i=1; a=rsa-sha256; t=1525908075; cv=none; d=google.com; s=arc-20160816; b=cl1qAJp0DtebbbHw4rSFIT4qNQ6lc0AtM595nxGbqAs9Hz+atXZvdEaTYeP5FzqyuG ZypPeDcGh8rIat79mTD+P0oJFtyig08twDfvXlXN7Y4jKCderQDI17rZtt0JHtbz4HGZ S0UKENzYUCQ6gc1H6JiqrrZ1l8JHpU6odSWANtl5JRXIjCs7mEOkytQbY3Qvpssi7mSy 4JvT/PlboVA5dFh46smt6AdrJHo7oAkBiyO1XhitoYH77/CyUmn0zpZ5y8MU2ZZXxCJb s4lhyVDtoVI09DQ8wmqtZskpw28etAtwhW6yMXqdFUiEANx7xcAtBFHmiwkbnkfaPQGx MJAg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:dkim-signature :arc-authentication-results; bh=o1IsiioJqwoiD0avnfH0xt5oy10sY3Qmdq/dC+POaNU=; b=i6YAPxGeHVSNiiWwA6WSaphHPyAE8a2Ny95Xa40ZeRWwVLECh8FOdT70QM3UhHa2pB UVXbfgn2B53GVsLl6xt2V+lny8U9ZQSpKSzKa6HtbCU3yWc0FWZ3AwtlTo1NkhUUu2o2 lW9H0KmbJw6A6YHSBilTUB8GgCF0uBJCLedsS8srutq4VGeul4axwwSLjT+eOUl5gdyg Od0j8Cv8/YKblX0+2SqLBdfmD0aqNtU8Xi5U3vwWSFUn+yNlMIqgcqYpWUSokIGe4ICf 66/5p5tfecWMjsiyZvzCdc0aBweDWBX1l/uPfiA6qCQG6frGR/vzNqP3j1JBrUd403JX tCdw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=IXcSF79I; spf=pass (google.com: domain of helgaas@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=helgaas@kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=IXcSF79I; spf=pass (google.com: domain of helgaas@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=helgaas@kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Date: Wed, 9 May 2018 18:21:11 -0500 From: Bjorn Helgaas To: poza@codeaurora.org Cc: Bjorn Helgaas , Philippe Ombredanne , Thomas Gleixner , Greg Kroah-Hartman , Kate Stewart , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Dongdong Liu , Keith Busch , Wei Zhang , Sinan Kaya , Timur Tabi , linux-pci-owner@vger.kernel.org Subject: Re: [PATCH v15 3/9] PCI/AER: Handle ERR_FATAL with removal and re-enumeration of devices Message-ID: <20180509232111.GA43216@bhelgaas-glaptop.roam.corp.google.com> References: <1525323838-1735-1-git-send-email-poza@codeaurora.org> <1525323838-1735-4-git-send-email-poza@codeaurora.org> <20180508235330.GN161390@bhelgaas-glaptop.roam.corp.google.com> <20180509130730.GA236548@bhelgaas-glaptop.roam.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1599417977501212020?= X-GMAIL-MSGID: =?utf-8?q?1600030585972738361?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Wed, May 09, 2018 at 06:44:53PM +0530, poza@codeaurora.org wrote: > On 2018-05-09 18:37, Bjorn Helgaas wrote: > > On Tue, May 08, 2018 at 06:53:30PM -0500, Bjorn Helgaas wrote: > > > On Thu, May 03, 2018 at 01:03:52AM -0400, Oza Pawandeep wrote: > > > > This patch alters the behavior of handling of ERR_FATAL, where removal > > > > of devices is initiated, followed by reset link, followed by > > > > re-enumeration. > > > > > > > > So the errors are handled in a different way as follows: > > > > ERR_NONFATAL => call driver recovery entry points > > > > ERR_FATAL => remove and re-enumerate > > > > > > > > please refer to Documentation/PCI/pci-error-recovery.txt for more details. > > > > > > > > Signed-off-by: Oza Pawandeep > > > > > > > > diff --git a/drivers/pci/pcie/aer/aerdrv.c b/drivers/pci/pcie/aer/aerdrv.c > > > > index 779b387..206f590 100644 > > > > --- a/drivers/pci/pcie/aer/aerdrv.c > > > > +++ b/drivers/pci/pcie/aer/aerdrv.c > > > > @@ -330,6 +330,13 @@ static pci_ers_result_t aer_root_reset(struct pci_dev *dev) > > > > reg32 |= ROOT_PORT_INTR_ON_MESG_MASK; > > > > pci_write_config_dword(dev, pos + PCI_ERR_ROOT_COMMAND, reg32); > > > > > > > > + /* > > > > + * This function is called only on ERR_FATAL now, and since > > > > + * the pci_report_resume is called only in ERR_NONFATAL case, > > > > + * the clearing part has to be taken care here. > > > > + */ > > > > + aer_error_resume(dev); > > > > > > I don't understand this part. Previously the ERR_FATAL path looked > > > like > > > this: > > > > > > do_recovery > > > reset_link > > > driver->reset_link > > > aer_root_reset > > > pci_reset_bridge_secondary_bus # <-- reset > > > broadcast_error_message(..., report_resume) > > > pci_walk_bus(..., report_resume, ...) > > > report_resume > > > if (cb == report_resume) > > > pci_cleanup_aer_uncorrect_error_status > > > pci_write_config_dword(PCI_ERR_UNCOR_STATUS) # <-- clear > > > status > > > > > > After this patch, it will look like this: > > > > > > do_recovery > > > do_fatal_recovery > > > pci_cleanup_aer_uncorrect_error_status > > > pci_write_config_dword(PCI_ERR_UNCOR_STATUS) # <-- clear > > > status > > > reset_link > > > driver->reset_link > > > aer_root_reset > > > pci_reset_bridge_secondary_bus # <-- reset > > > aer_error_resume > > > pcie_capability_write_word(PCI_EXP_DEVSTA) # > > > <-- clear more > > > pci_write_config_dword(PCI_ERR_UNCOR_STATUS) # > > > <-- clear status > > > > > > So if I'm understanding correctly, the new path clears the status too > > > early, then clears it again (plus clearing DEVSTA, which we didn't do > > > before) later. > > > > > > I would think we would want to leave aer_root_reset() alone, and > > > just move > > > the pci_cleanup_aer_uncorrect_error_status() in do_fatal_recovery() > > > down so > > > it happens after we call reset_link(). That way the reset/clear > > > sequence > > > would be the same as it was before. > > > > I've been fiddling with this a bit myself and will post the results to > > see > > what you think. > > > ok so you are suggesting to move pci_cleanup_aer_uncorrect_error_status down > which I can do. > > And not to call aer_error_resume, because you think its clearing the status > again. > > following code: calls aer_error_resume. > pci_broadcast_error_message() > /* > * If the error is reported by an end point, we think this > * error is related to the upstream link of the end point. > */ > if (state == pci_channel_io_normal) > /* > * the error is non fatal so the bus is ok, just > invoke > * the callback for the function that logged the > error. > */ > cb(dev, &result_data); > else > pci_walk_bus(dev->bus, cb, &result_data); Holy crap, I thought this could not possibly get any more complicated, but you're right; we do actually call aer_error_resume() today via an extremely convoluted path: do_recovery(pci_dev) broadcast_error_message(..., error_detected, ...) if (AER_FATAL) reset_link(pci_dev) udev = BRIDGE ? pci_dev : pci_dev->bus->self driver->reset_link(udev) aer_root_reset(udev) if (CAN_RECOVER) broadcast_error_message(..., mmio_enabled, ...) if (NEED_RESET) broadcast_error_message(..., slot_reset, ...) broadcast_error_message(dev, ..., report_resume, ...) if (BRIDGE) report_resume driver->resume pcie_portdrv_err_resume device_for_each_child(..., resume_iter) resume_iter driver->error_resume aer_error_resume pci_cleanup_aer_uncorrect_error_status(pci_dev) # only if BRIDGE pci_write_config_dword(PCI_ERR_UNCOR_STATUS) aerdriver is the only port service driver that implements .error_resume(), and aerdriver only binds to root ports. I can't really believe all these device_for_each_child()/resume_iter() gyrations are necessary when this is AER code calling AER code. Bjorn