From: Andy Shevchenko <andy.shevchenko@gmail.com> To: Dexuan Cui <decui@microsoft.com> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>, Bjorn Helgaas <bhelgaas@google.com>, "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>, KY Srinivasan <kys@microsoft.com>, Stephen Hemminger <sthemmin@microsoft.com>, "olaf@aepfle.de" <olaf@aepfle.de>, "apw@canonical.com" <apw@canonical.com>, "jasowang@redhat.com" <jasowang@redhat.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "driverdev-devel@linuxdriverproject.org" <driverdev-devel@linuxdriverproject.org>, Haiyang Zhang <haiyangz@microsoft.com>, "vkuznets@redhat.com" <vkuznets@redhat.com>, "marcelo.cerri@canonical.com" <marcelo.cerri@canonical.com> Subject: Re: [PATCH] PCI: hv: Do not wait forever on a device that has disappeared Date: Wed, 30 May 2018 00:20:57 +0300 [thread overview] Message-ID: <CAHp75Vd9kiyOaSbaK6c4b7ucF23kgP0yQxKpUAGrjHgKfJprXA@mail.gmail.com> (raw) In-Reply-To: <KL1P15301MB0006DF4209AEE3809ABD303FBF6B0@KL1P15301MB0006.APCP153.PROD.OUTLOOK.COM> On Thu, May 24, 2018 at 12:12 AM, Dexuan Cui <decui@microsoft.com> wrote: > > Before the guest finishes the device initialization, the device can be > removed anytime by the host, and after that the host won't respond to > the guest's request, so the guest should be prepared to handle this > case. > + while (true) { > + if (hdev->channel->rescind) { > + dev_warn_once(&hdev->device, "The device is gone.\n"); > + return -ENODEV; > + } > + > + if (wait_for_completion_timeout(comp, HZ / 10)) > + break; > + } Infinite loops are usually a red flags. What's wrong with simple: do { ... } while (wait_...(...) == 0); ? > + if (!ret) > + ret = wait_for_response(hdev, &comp); Better to use well established patterns, i.e. if (ret) return ret; > + if (!ret) > + ret = wait_for_response(hdev, &comp_pkt.host_event); Here it looks okay on the first glance, but better to think about it again and refactor. -- With Best Regards, Andy Shevchenko
WARNING: multiple messages have this Message-ID (diff)
From: Andy Shevchenko <andy.shevchenko@gmail.com> To: Dexuan Cui <decui@microsoft.com> Cc: "olaf@aepfle.de" <olaf@aepfle.de>, Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>, Stephen Hemminger <sthemmin@microsoft.com>, "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>, "jasowang@redhat.com" <jasowang@redhat.com>, "driverdev-devel@linuxdriverproject.org" <driverdev-devel@linuxdriverproject.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "apw@canonical.com" <apw@canonical.com>, "marcelo.cerri@canonical.com" <marcelo.cerri@canonical.com>, Bjorn Helgaas <bhelgaas@google.com>, "vkuznets@redhat.com" <vkuznets@redhat.com>, Haiyang Zhang <haiyangz@microsoft.com> Subject: Re: [PATCH] PCI: hv: Do not wait forever on a device that has disappeared Date: Wed, 30 May 2018 00:20:57 +0300 [thread overview] Message-ID: <CAHp75Vd9kiyOaSbaK6c4b7ucF23kgP0yQxKpUAGrjHgKfJprXA@mail.gmail.com> (raw) In-Reply-To: <KL1P15301MB0006DF4209AEE3809ABD303FBF6B0@KL1P15301MB0006.APCP153.PROD.OUTLOOK.COM> On Thu, May 24, 2018 at 12:12 AM, Dexuan Cui <decui@microsoft.com> wrote: > > Before the guest finishes the device initialization, the device can be > removed anytime by the host, and after that the host won't respond to > the guest's request, so the guest should be prepared to handle this > case. > + while (true) { > + if (hdev->channel->rescind) { > + dev_warn_once(&hdev->device, "The device is gone.\n"); > + return -ENODEV; > + } > + > + if (wait_for_completion_timeout(comp, HZ / 10)) > + break; > + } Infinite loops are usually a red flags. What's wrong with simple: do { ... } while (wait_...(...) == 0); ? > + if (!ret) > + ret = wait_for_response(hdev, &comp); Better to use well established patterns, i.e. if (ret) return ret; > + if (!ret) > + ret = wait_for_response(hdev, &comp_pkt.host_event); Here it looks okay on the first glance, but better to think about it again and refactor. -- With Best Regards, Andy Shevchenko _______________________________________________ devel mailing list devel@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
next prev parent reply other threads:[~2018-05-29 21:21 UTC|newest] Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-05-23 21:12 [PATCH] PCI: hv: Do not wait forever on a device that has disappeared Dexuan Cui 2018-05-23 21:12 ` Dexuan Cui 2018-05-24 12:41 ` Lorenzo Pieralisi 2018-05-24 12:41 ` Lorenzo Pieralisi 2018-05-24 23:55 ` Dexuan Cui 2018-05-24 23:55 ` Dexuan Cui 2018-05-24 23:55 ` Dexuan Cui 2018-05-25 10:29 ` Lorenzo Pieralisi 2018-05-25 10:29 ` Lorenzo Pieralisi 2018-05-25 11:43 ` Haiyang Zhang 2018-05-25 11:43 ` Haiyang Zhang 2018-05-25 11:43 ` Haiyang Zhang 2018-05-25 13:56 ` Lorenzo Pieralisi 2018-05-25 13:56 ` Lorenzo Pieralisi 2018-05-29 0:19 ` Michael Kelley (EOSG) 2018-05-29 0:19 ` Michael Kelley (EOSG) 2018-05-29 0:19 ` Michael Kelley (EOSG) 2018-05-29 19:58 ` Dexuan Cui 2018-05-29 19:58 ` Dexuan Cui 2018-05-29 19:58 ` Dexuan Cui 2018-05-31 16:40 ` Michael Kelley (EOSG) 2018-05-31 16:40 ` Michael Kelley (EOSG) 2018-05-31 16:40 ` Michael Kelley (EOSG) 2018-05-31 21:01 ` Dexuan Cui 2018-05-31 21:01 ` Dexuan Cui 2018-05-31 21:01 ` Dexuan Cui 2018-05-29 21:20 ` Andy Shevchenko [this message] 2018-05-29 21:20 ` Andy Shevchenko 2018-05-29 21:28 ` Dexuan Cui 2018-05-29 21:28 ` Dexuan Cui 2018-05-29 21:28 ` Dexuan Cui
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