From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 800372F3C26; Tue, 24 Mar 2026 22:49:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774392578; cv=none; b=d4oYCerbAPHI+PUw1QHPUqFMK/CgTotK2V9vqLLbIQzS4vIqFcs6+/SBynO8NC/8w9U8StlK4c1Fc1OQtnweUTe4VdkZCan4xmdVzTaTSacFiIEsr1GtzBpHHQfX1VH2rTojfGIGpBUO6bfHoQj3uPviZe+V6ix1Ximk4qs/bdY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774392578; c=relaxed/simple; bh=JW3WSzqzEacKIr5TFoj4Y2bRWpAi138QmuJ67XAY1fs=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=gX8xljDSI+rX7xfvHI7PCKCDYHYLmOjLfvCtC954JHes/riUjHYonPST1Ggo/DKbx5127OqXKkXFFP2Fw4mw7rN1JNkc3eeThPTpeF+Ai5pBsN0t+ecl29ChKUEnDUBrxKYcgvQxd9YIOS1pF1lHP7qf+maHtMY82WCbCRh2xAA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WGsc7FOh; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="WGsc7FOh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E038BC19424; Tue, 24 Mar 2026 22:49:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774392578; bh=JW3WSzqzEacKIr5TFoj4Y2bRWpAi138QmuJ67XAY1fs=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=WGsc7FOhtji9dar4UgVNyHHmaBrGIUm+8NPf0jpN7cmpCshcw1MGvYw9CVTG5GyCO ESvix7VqD/2yIbqDRs3sJ/2rdXcI2d6KjaBAhNBosRsxVENH8D2ACZs/kDB49wj037 9svJ2NGQN5q/02EAvG6W0TjNGF2uprs5kZhwAq5W3lyQ5AtZ/2DUPVnrMVtKv+u+KV HueQnCn9R4TIvB9Ntjcd/LOBoUl4NeFpmPwiVh9zlAGOfkR1ofjHXFDvL5KquTQCW4 +ASJS54jAN7Wcu7BYEtDJWrhlLQru15ZNgM/0IaMT7lMVD9L2elsWHDE7+/lrR+kP1 DsfMYbAOxlhdw== Date: Tue, 24 Mar 2026 17:49:36 -0500 From: Bjorn Helgaas To: Farhan Ali Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, lukas@wunner.de, alex@shazbot.org, kbusch@kernel.org, clg@redhat.com, stable@vger.kernel.org, schnelle@linux.ibm.com, mjrosato@linux.ibm.com, Benjamin Block Subject: Re: [PATCH v11 4/9] PCI: Add additional checks for flr reset Message-ID: <20260324224936.GA1157694@bhelgaas> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260316191544.2279-5-alifm@linux.ibm.com> On Mon, Mar 16, 2026 at 12:15:39PM -0700, Farhan Ali wrote: > If a device is in an error state, then any reads of device registers can > return error value. Add additional checks to validate if a device is in an > error state before doing an flr reset. s/flr/FLR/ (also in subject) Also please extend the subject to say something specific about the "additional checks". E.g., PCI: Fail FLR when config space inaccessible > Cc: stable@vger.kernel.org > Reviewed-by: Benjamin Block > Reviewed-by: Niklas Schnelle > Signed-off-by: Farhan Ali > --- > drivers/pci/pci.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index 373421f4b9d8..8e4d924f4e88 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -4371,12 +4371,19 @@ EXPORT_SYMBOL_GPL(pcie_flr); > */ > int pcie_reset_flr(struct pci_dev *dev, bool probe) > { > + u32 reg; > + > if (dev->dev_flags & PCI_DEV_FLAGS_NO_FLR_RESET) > return -ENOTTY; > > if (!(dev->devcap & PCI_EXP_DEVCAP_FLR)) > return -ENOTTY; > > + if (pcie_capability_read_dword(dev, PCI_EXP_DEVCAP, ®)) { > + pci_warn(dev, "Device unable to do an FLR\n"); > + return -ENOTTY; > + } I guess the point of this is to detect devices that are inaccessible? The same sort of thing as in pci_dev_save_and_disable() from patch 3/9? But we use "dev->error_state == pci_channel_io_perm_failure" instead? No matter what we do, this has the same race as in patch 3/9. And I think using dev->error_state also depends on AER being enabled, which cuts out many PCIe devices. I think using the same exact code as in pci_dev_save_and_disable() would be more straightforward. And also the same sort of wording in the message, e.g., "Device config space inaccessible; unable to FLR" or similar. I foresee many of these messages in my future, and it will be helpful to have a specific clue about why FLR failed :) > if (probe) > return 0; > > -- > 2.43.0 >