linux-kernel - [PATCH] PCI/LINK: Request a one-shot IRQ with NULL handler

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Message-Id: <20190325182338.13609-1-bp@alien8.de>
Date:   Mon, 25 Mar 2019 19:23:38 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Lukas Wunner <lukas@...ner.de>,
        Alexandru Gagniuc <mr.nuke.me@...il.com>,
        linux-pci@...r.kernel.org
Subject: [PATCH] PCI/LINK: Request a one-shot IRQ with NULL handler

From: Borislav Petkov <bp@...e.de>

Booting v5.1-rc1 causes these new messages in dmesg here:

  genirq: Threaded irq requested with handler=NULL and !ONESHOT for irq 24
  pcie_bw_notification: probe of 0000:00:02.0:pcie010 failed with error -22

because requesting a threaded IRQ with NULL handler needs to be oneshot.
Otherwise a level-triggered interrupt endless loop can happen, see the
detailed explanation above the "Threaded irq... " error message in
kernel/irq/manage.c.

And PCI-MSI type interrupts are one-shot safe but not in the IOAPIC
case:

  24: ... IO-APIC   28-fasteoi   PCIe BW notif, PCIe BW notif, PCIe BW notif
  25: ... IO-APIC   29-fasteoi   PCIe BW notif, PCIe BW notif

Make the BW notification handler oneshot too.

Fixes: e8303bb7a75c ("PCI/LINK: Report degraded links via link bandwidth notification")
Suggested-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Lukas Wunner <lukas@...ner.de>
Cc: Alexandru Gagniuc <mr.nuke.me@...il.com>
Cc: linux-pci@...r.kernel.org
---
 drivers/pci/pcie/bw_notification.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/pcie/bw_notification.c b/drivers/pci/pcie/bw_notification.c
index d2eae3b7cc0f..16e11c09f6bd 100644
--- a/drivers/pci/pcie/bw_notification.c
+++ b/drivers/pci/pcie/bw_notification.c
@@ -81,7 +81,7 @@ static int pcie_bandwidth_notification_probe(struct pcie_device *srv)
 		return -ENODEV;
 
 	ret = request_threaded_irq(srv->irq, NULL, pcie_bw_notification_handler,
-				   IRQF_SHARED, "PCIe BW notif", srv);
+				   IRQF_SHARED | IRQF_ONESHOT, "PCIe BW notif", srv);
 	if (ret)
 		return ret;
 
-- 
2.21.0