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[98.195.139.126]) by smtp.gmail.com with ESMTPSA id 111sm46397773otf.51.2018.11.05.16.32.03 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 05 Nov 2018 16:32:03 -0800 (PST) Subject: Re: [PATCH v2] PCI/MSI: Don't touch MSI bits when the PCI device is disconnected To: linux-pci@vger.kernel.org, bhelgaas@google.com Cc: keith.busch@intel.com, alex_gagniuc@dellteam.com, austin_bolen@dell.com, shyam_iyer@dell.com, linux-kernel@vger.kernel.org References: <20180918221501.13112-1-mr.nuke.me@gmail.com> From: "Alex G." Message-ID: <3c949cf2-bb7f-6b67-f2cb-9f4859b56cfb@gmail.com> Date: Mon, 5 Nov 2018 18:32:02 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180918221501.13112-1-mr.nuke.me@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ping On 09/18/2018 05:15 PM, Alexandru Gagniuc wrote: > When a PCI device is gone, we don't want to send IO to it if we can > avoid it. We expose functionality via the irq_chip structure. As > users of that structure may not know about the underlying PCI device, > it's our responsibility to guard against removed devices. > > .irq_write_msi_msg() is already guarded inside __pci_write_msi_msg(). > .irq_mask/unmask() are not. Guard them for completeness. > > For example, surprise removal of a PCIe device triggers teardown. This > touches the irq_chips ops some point to disable the interrupts. I/O > generated here can crash the system on firmware-first machines. > Not triggering the IO in the first place greatly reduces the > possibility of the problem occurring. > > Signed-off-by: Alexandru Gagniuc > --- > drivers/pci/msi.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c > index f2ef896464b3..f31058fd2260 100644 > --- a/drivers/pci/msi.c > +++ b/drivers/pci/msi.c > @@ -227,6 +227,9 @@ static void msi_set_mask_bit(struct irq_data *data, u32 flag) > { > struct msi_desc *desc = irq_data_get_msi_desc(data); > > + if (pci_dev_is_disconnected(msi_desc_to_pci_dev(desc))) > + return; > + > if (desc->msi_attrib.is_msix) { > msix_mask_irq(desc, flag); > readl(desc->mask_base); /* Flush write to device */ >