linux-kernel - [PATCH 3/4] PCI/hotplug: reset_lock is not required synchronizing with irq thread

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Message-Id: <20250313142333.5792-4-ilpo.jarvinen@linux.intel.com>
Date: Thu, 13 Mar 2025 16:23:32 +0200
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Bjorn Helgaas <bhelgaas@...gle.com>,
	linux-pci@...r.kernel.org,
	Guenter Roeck <groeck@...iper.net>,
	Lukas Wunner <lukas@...ner.de>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Rajat Jain <rajatxjain@...il.com>,
	Joel Mathew Thomas <proxy0@...amail.com>,
	linux-kernel@...r.kernel.org
Cc: Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: [PATCH 3/4] PCI/hotplug: reset_lock is not required synchronizing with irq thread

Disabling HPIE (Hot-Plug Interrupt Enable) and synchronizing with irq
handling in pciehp_reset_slot() is enough to ensure no pending events
are processed during the slot reset. Thus, there is no need to take
reset_lock in the IRQ thread.

Suggested-by: Lukas Wunner <lukas@...ner.de>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
---
 drivers/pci/hotplug/pciehp_hpc.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
index 634cf5004f76..26150a6b48f4 100644
--- a/drivers/pci/hotplug/pciehp_hpc.c
+++ b/drivers/pci/hotplug/pciehp_hpc.c
@@ -748,12 +748,10 @@ static irqreturn_t pciehp_ist(int irq, void *dev_id)
 	 * Disable requests have higher priority than Presence Detect Changed
 	 * or Data Link Layer State Changed events.
 	 */
-	down_read_nested(&ctrl->reset_lock, ctrl->depth);
 	if (events & DISABLE_SLOT)
 		pciehp_handle_disable_request(ctrl);
 	else if (events & (PCI_EXP_SLTSTA_PDC | PCI_EXP_SLTSTA_DLLSC))
 		pciehp_handle_presence_or_link_change(ctrl, events);
-	up_read(&ctrl->reset_lock);
 
 	ret = IRQ_HANDLED;
 out:
-- 
2.39.5