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Mon, 5 Mar 2018 19:22:19 +0000 From: Dexuan Cui To: "bhelgaas@google.com" , "linux-pci@vger.kernel.org" , KY Srinivasan , Stephen Hemminger , "olaf@aepfle.de" , "apw@canonical.com" , "jasowang@redhat.com" CC: "linux-kernel@vger.kernel.org" , "driverdev-devel@linuxdriverproject.org" , Haiyang Zhang , "vkuznets@redhat.com" , "marcelo.cerri@canonical.com" , "Michael Kelley (EOSG)" , Dexuan Cui , Jack Morgenstein , "stable@vger.kernel.org" Subject: [PATCH v2 4/6] PCI: hv: remove hbus->enum_sem Thread-Topic: [PATCH v2 4/6] PCI: hv: remove hbus->enum_sem Thread-Index: AQHTtLdHnsXJFvisFEWUranPC/7lKA== Date: Mon, 5 Mar 2018 19:22:19 +0000 Message-ID: <20180305192134.32207-5-decui@microsoft.com> References: <20180305192134.32207-1-decui@microsoft.com> In-Reply-To: <20180305192134.32207-1-decui@microsoft.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: git-send-email 2.15.1 authentication-results: spf=none (sender IP is ) smtp.mailfrom=decui@microsoft.com; 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DIR:OUT; SFP:1102; SCL:1; SRVR:KL1P15301MB0039; H:KL1P15301MB0006.APCP153.PROD.OUTLOOK.COM; FPR:; SPF:None; PTR:InfoNoRecords; A:1; MX:1; LANG:en; received-spf: None (protection.outlook.com: microsoft.com does not designate permitted sender hosts) x-microsoft-antispam-message-info: eEUAGJ0cKpiodAoC7XUXhVAc4m0BKQdkkWnxnfB8lQDwHwTWlqNOgZUkCdJY9QoOmZQERAj01xbTa5G71at51zupuek2B90VjN9HEQeF+ASqYKergnQQc5SNv2bISW5sRd1BndNwczFYDvHGDYosXqe7dHXx27MrhijXHnZzQKu3VnF7s96I20e6/RUE7UjHK0YA5HC0dfDvErRMB3N93vkQYZmpP3kH/P+nh+ORX7l7zDThTa9I9K0wEC+Q8CigwSGdbvOrXnGKRgxHwkpLMOPNAnnYyur7O4r15TQFs2CaoCDcaCBfJJg7tRdWwODD+zD1JqbTa+a3ZFIS2bOhQA== spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-Network-Message-Id: e4317f52-3c8a-4a1c-920f-08d582ce6a11 X-MS-Exchange-CrossTenant-originalarrivaltime: 05 Mar 2018 19:22:19.0978 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: KL1P15301MB0039 Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Since we serialize the present/eject work items now, we don't need the semaphore any more. This is suggested by Michael Kelley. Signed-off-by: Dexuan Cui Cc: Vitaly Kuznetsov Cc: Jack Morgenstein Cc: stable@vger.kernel.org Cc: Stephen Hemminger Cc: K. Y. Srinivasan Cc: Michael Kelley (EOSG) --- drivers/pci/host/pci-hyperv.c | 17 ++--------------- 1 file changed, 2 insertions(+), 15 deletions(-) diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c index aaee41faf55f..3a385212f666 100644 --- a/drivers/pci/host/pci-hyperv.c +++ b/drivers/pci/host/pci-hyperv.c @@ -447,7 +447,6 @@ struct hv_pcibus_device { spinlock_t device_list_lock; /* Protect lists below */ void __iomem *cfg_addr; - struct semaphore enum_sem; struct list_head resources_for_children; struct list_head children; @@ -1592,12 +1591,8 @@ static struct hv_pci_dev *get_pcichild_wslot(struct hv_pcibus_device *hbus, * It must also treat the omission of a previously observed device as * notification that the device no longer exists. * - * Note that this function is a work item, and it may not be - * invoked in the order that it was queued. Back to back - * updates of the list of present devices may involve queuing - * multiple work items, and this one may run before ones that - * were sent later. As such, this function only does something - * if is the last one in the queue. + * Note that this function is serialized with hv_eject_device_work(), + * because both are pushed to the ordered workqueue hbus->wq. */ static void pci_devices_present_work(struct work_struct *work) { @@ -1618,11 +1613,6 @@ static void pci_devices_present_work(struct work_struct *work) INIT_LIST_HEAD(&removed); - if (down_interruptible(&hbus->enum_sem)) { - put_hvpcibus(hbus); - return; - } - /* Pull this off the queue and process it if it was the last one. */ spin_lock_irqsave(&hbus->device_list_lock, flags); while (!list_empty(&hbus->dr_list)) { @@ -1639,7 +1629,6 @@ static void pci_devices_present_work(struct work_struct *work) spin_unlock_irqrestore(&hbus->device_list_lock, flags); if (!dr) { - up(&hbus->enum_sem); put_hvpcibus(hbus); return; } @@ -1726,7 +1715,6 @@ static void pci_devices_present_work(struct work_struct *work) break; } - up(&hbus->enum_sem); put_hvpcibus(hbus); kfree(dr); } @@ -2460,7 +2448,6 @@ static int hv_pci_probe(struct hv_device *hdev, spin_lock_init(&hbus->config_lock); spin_lock_init(&hbus->device_list_lock); spin_lock_init(&hbus->retarget_msi_interrupt_lock); - sema_init(&hbus->enum_sem, 1); init_completion(&hbus->remove_event); hbus->wq = alloc_ordered_workqueue("hv_pci_%x", 0, hbus->sysdata.domain);