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[2.214.2.133]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c24962bbea6sm805385066b.27.2026.08.23.11.35.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 23 Aug 2026 11:35:10 -0700 (PDT) From: Abhin Parekadan Jose To: lukas@wunner.de, mst@redhat.com Cc: virtualization@lists.linux.dev, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, bhelgaas@google.com, kbusch@kernel.org, stefanha@redhat.com, parav@nvidia.com, axboe@kernel.dk, kees@kernel.org, ilpo.jarvinen@linux.intel.com, xueshuai@linux.alibaba.com, Abhin Parekadan Jose Subject: [PATCH RFC 3/3] pciehp_hpc: workaround to not wait in pciehp_isr on surprise removal Date: Sun, 23 Aug 2026 18:34:55 +0000 Message-ID: <20260823183458.982699-4-abhinjoses@gmail.com> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20260823183458.982699-1-abhinjoses@gmail.com> References: <20260823183458.982699-1-abhinjoses@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit - Add pciehp_disconnect_work() , this function is used using schedule_work from pciehp_isr allowing us to not wait in pciehp_isr() - pciehp_disconnect_work() is scheduled only if the card is not detected (PDS bit = 0). The PDS bit can be used to differentiate between a safe and surprise removal. Signed-off-by: Abhin Parekadan Jose --- drivers/pci/hotplug/pciehp_hpc.c | 47 ++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c index 4c62140a3cb4..69ed6b060e9d 100644 --- a/drivers/pci/hotplug/pciehp_hpc.c +++ b/drivers/pci/hotplug/pciehp_hpc.c @@ -620,6 +620,40 @@ static void pciehp_ignore_link_change(struct controller *ctrl, up_read(&ctrl->reset_lock); } +/* + * Workaround to not wait in the isr. + */ +static void pciehp_disconnect_work(struct work_struct *work) +{ + struct controller *ctrl = container_of(work, struct controller, + disconnect_work); + struct pci_dev *pdev = ctrl_dev(ctrl); + int events; + + events = atomic_read(&ctrl->pending_events); + + /* + * Ignore Link Down/Up events caused by Downstream Port Containment + * if recovery succeeded, or caused by Secondary Bus Reset, + * suspend to D3cold, firmware update, FPGA reconfiguration, etc. + */ + if ((events & (PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_DLLSC)) && + (pci_dpc_recovered(pdev) || pci_hp_spurious_link_change(pdev)) && + ctrl->state == ON_STATE) { + // Ignore the link change events and return to normal operation. + // Could also wait here if needed. + return; + } + + struct pci_bus *bus = ctrl->pcie->port->subordinate; + + /* the card may have returned. */ + if (!bus || pciehp_card_present(ctrl) != 0) + return; + + pci_walk_bus(bus, pci_dev_set_disconnected, NULL); +} + static irqreturn_t pciehp_isr(int irq, void *dev_id) { struct controller *ctrl = (struct controller *)dev_id; @@ -722,6 +756,17 @@ static irqreturn_t pciehp_isr(int irq, void *dev_id) /* Save pending events for consumption by IRQ thread. */ atomic_or(events, &ctrl->pending_events); + + // presence change events + if (events & (PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_DLLSC)) { + // Get PDS bit to determine if card is present or not + int present = pciehp_card_present(ctrl); + if (!present) { // for sure the card is not present + schedule_work(&ctrl->disconnect_work); + // After this we are no longer in isr and can wait. + } + } + return IRQ_WAKE_THREAD; } @@ -1036,6 +1081,7 @@ struct controller *pcie_init(struct pcie_device *dev) init_waitqueue_head(&ctrl->requester); init_waitqueue_head(&ctrl->queue); INIT_DELAYED_WORK(&ctrl->button_work, pciehp_queue_pushbutton_work); + INIT_WORK(&ctrl->disconnect_work, pciehp_disconnect_work); dbg_ctrl(ctrl); down_read(&pci_bus_sem); @@ -1096,6 +1142,7 @@ struct controller *pcie_init(struct pcie_device *dev) void pciehp_release_ctrl(struct controller *ctrl) { cancel_delayed_work_sync(&ctrl->button_work); + cancel_work_sync(&ctrl->disconnect_work); kfree(ctrl); } -- 2.51.1