Patch "PCI: host: Mark PCIe/PCI (MSI) IRQ cascade handlers as IRQF_NO_THREAD" has been added to the 4.3-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    PCI: host: Mark PCIe/PCI (MSI) IRQ cascade handlers as IRQF_NO_THREAD

to the 4.3-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     pci-host-mark-pcie-pci-msi-irq-cascade-handlers-as-irqf_no_thread.patch
and it can be found in the queue-4.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 8ff0ef996ca00028519c70e8d51d32bd37eb51dc Mon Sep 17 00:00:00 2001
From: Grygorii Strashko <grygorii.strashko@ti.com>
Date: Thu, 10 Dec 2015 21:18:20 +0200
Subject: PCI: host: Mark PCIe/PCI (MSI) IRQ cascade handlers as IRQF_NO_THREAD
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Grygorii Strashko <grygorii.strashko@ti.com>

commit 8ff0ef996ca00028519c70e8d51d32bd37eb51dc upstream.

On -RT and if kernel is booting with "threadirqs" cmd line parameter,
PCIe/PCI (MSI) IRQ cascade handlers (like dra7xx_pcie_msi_irq_handler())
will be forced threaded and, as result, will generate warnings like this:

  WARNING: CPU: 1 PID: 82 at kernel/irq/handle.c:150 handle_irq_event_percpu+0x14c/0x174()
  irq 460 handler irq_default_primary_handler+0x0/0x14 enabled interrupts
  Backtrace:
   (warn_slowpath_common) from (warn_slowpath_fmt+0x38/0x40)
   (warn_slowpath_fmt) from (handle_irq_event_percpu+0x14c/0x174)
   (handle_irq_event_percpu) from (handle_irq_event+0x84/0xb8)
   (handle_irq_event) from (handle_simple_irq+0x90/0x118)
   (handle_simple_irq) from (generic_handle_irq+0x30/0x44)
   (generic_handle_irq) from (dra7xx_pcie_msi_irq_handler+0x7c/0x8c)
   (dra7xx_pcie_msi_irq_handler) from (irq_forced_thread_fn+0x28/0x5c)
   (irq_forced_thread_fn) from (irq_thread+0x128/0x204)

This happens because all of them invoke generic_handle_irq() from the
requested handler.  generic_handle_irq() grabs raw_locks and thus needs to
run in raw-IRQ context.

This issue was originally reproduced on TI dra7-evem, but, as was
identified during discussion [1], other hosts can also suffer from this
issue.  Fix all them at once by marking PCIe/PCI (MSI) IRQ cascade handlers
IRQF_NO_THREAD explicitly.

[1] http://lkml.kernel.org/r/1448027966-21610-1-git-send-email-grygorii.strashko@ti.com

[bhelgaas: add stable tag, fix typos]
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Lucas Stach <l.stach@pengutronix.de> (for imx6)
CC: Kishon Vijay Abraham I <kishon@ti.com>
CC: Jingoo Han <jingoohan1@gmail.com>
CC: Kukjin Kim <kgene@kernel.org>
CC: Krzysztof Kozlowski <k.kozlowski@samsung.com>
CC: Richard Zhu <Richard.Zhu@freescale.com>
CC: Thierry Reding <thierry.reding@gmail.com>
CC: Stephen Warren <swarren@wwwdotorg.org>
CC: Alexandre Courbot <gnurou@gmail.com>
CC: Simon Horman <horms@verge.net.au>
CC: Pratyush Anand <pratyush.anand@gmail.com>
CC: Michal Simek <michal.simek@xilinx.com>
CC: "Sören Brinkmann" <soren.brinkmann@xilinx.com>
CC: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/pci/host/pci-dra7xx.c     |    3 ++-
 drivers/pci/host/pci-exynos.c     |    3 ++-
 drivers/pci/host/pci-imx6.c       |    3 ++-
 drivers/pci/host/pci-tegra.c      |    2 +-
 drivers/pci/host/pcie-rcar.c      |    6 ++++--
 drivers/pci/host/pcie-spear13xx.c |    3 ++-
 drivers/pci/host/pcie-xilinx.c    |    3 ++-
 7 files changed, 15 insertions(+), 8 deletions(-)

--- a/drivers/pci/host/pci-dra7xx.c
+++ b/drivers/pci/host/pci-dra7xx.c
@@ -295,7 +295,8 @@ static int __init dra7xx_add_pcie_port(s
 	}
 
 	ret = devm_request_irq(&pdev->dev, pp->irq,
-			       dra7xx_pcie_msi_irq_handler, IRQF_SHARED,
+			       dra7xx_pcie_msi_irq_handler,
+			       IRQF_SHARED | IRQF_NO_THREAD,
 			       "dra7-pcie-msi",	pp);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to request irq\n");
--- a/drivers/pci/host/pci-exynos.c
+++ b/drivers/pci/host/pci-exynos.c
@@ -523,7 +523,8 @@ static int __init exynos_add_pcie_port(s
 
 		ret = devm_request_irq(&pdev->dev, pp->msi_irq,
 					exynos_pcie_msi_irq_handler,
-					IRQF_SHARED, "exynos-pcie", pp);
+					IRQF_SHARED | IRQF_NO_THREAD,
+					"exynos-pcie", pp);
 		if (ret) {
 			dev_err(&pdev->dev, "failed to request msi irq\n");
 			return ret;
--- a/drivers/pci/host/pci-imx6.c
+++ b/drivers/pci/host/pci-imx6.c
@@ -536,7 +536,8 @@ static int __init imx6_add_pcie_port(str
 
 		ret = devm_request_irq(&pdev->dev, pp->msi_irq,
 				       imx6_pcie_msi_handler,
-				       IRQF_SHARED, "mx6-pcie-msi", pp);
+				       IRQF_SHARED | IRQF_NO_THREAD,
+				       "mx6-pcie-msi", pp);
 		if (ret) {
 			dev_err(&pdev->dev, "failed to request MSI irq\n");
 			return -ENODEV;
--- a/drivers/pci/host/pci-tegra.c
+++ b/drivers/pci/host/pci-tegra.c
@@ -1288,7 +1288,7 @@ static int tegra_pcie_enable_msi(struct
 
 	msi->irq = err;
 
-	err = request_irq(msi->irq, tegra_pcie_msi_irq, 0,
+	err = request_irq(msi->irq, tegra_pcie_msi_irq, IRQF_NO_THREAD,
 			  tegra_msi_irq_chip.name, pcie);
 	if (err < 0) {
 		dev_err(&pdev->dev, "failed to request IRQ: %d\n", err);
--- a/drivers/pci/host/pcie-rcar.c
+++ b/drivers/pci/host/pcie-rcar.c
@@ -694,14 +694,16 @@ static int rcar_pcie_enable_msi(struct r
 
 	/* Two irqs are for MSI, but they are also used for non-MSI irqs */
 	err = devm_request_irq(&pdev->dev, msi->irq1, rcar_pcie_msi_irq,
-			       IRQF_SHARED, rcar_msi_irq_chip.name, pcie);
+			       IRQF_SHARED | IRQF_NO_THREAD,
+			       rcar_msi_irq_chip.name, pcie);
 	if (err < 0) {
 		dev_err(&pdev->dev, "failed to request IRQ: %d\n", err);
 		goto err;
 	}
 
 	err = devm_request_irq(&pdev->dev, msi->irq2, rcar_pcie_msi_irq,
-			       IRQF_SHARED, rcar_msi_irq_chip.name, pcie);
+			       IRQF_SHARED | IRQF_NO_THREAD,
+			       rcar_msi_irq_chip.name, pcie);
 	if (err < 0) {
 		dev_err(&pdev->dev, "failed to request IRQ: %d\n", err);
 		goto err;
--- a/drivers/pci/host/pcie-spear13xx.c
+++ b/drivers/pci/host/pcie-spear13xx.c
@@ -281,7 +281,8 @@ static int spear13xx_add_pcie_port(struc
 		return -ENODEV;
 	}
 	ret = devm_request_irq(dev, pp->irq, spear13xx_pcie_irq_handler,
-			       IRQF_SHARED, "spear1340-pcie", pp);
+			       IRQF_SHARED | IRQF_NO_THREAD,
+			       "spear1340-pcie", pp);
 	if (ret) {
 		dev_err(dev, "failed to request irq %d\n", pp->irq);
 		return ret;
--- a/drivers/pci/host/pcie-xilinx.c
+++ b/drivers/pci/host/pcie-xilinx.c
@@ -781,7 +781,8 @@ static int xilinx_pcie_parse_dt(struct x
 
 	port->irq = irq_of_parse_and_map(node, 0);
 	err = devm_request_irq(dev, port->irq, xilinx_pcie_intr_handler,
-			       IRQF_SHARED, "xilinx-pcie", port);
+			       IRQF_SHARED | IRQF_NO_THREAD,
+			       "xilinx-pcie", port);
 	if (err) {
 		dev_err(dev, "unable to request irq %d\n", port->irq);
 		return err;


Patches currently in stable-queue which might be from grygorii.strashko@ti.com are

queue-4.3/i2c-fix-wakeup-irq-parsing.patch
queue-4.3/pci-host-mark-pcie-pci-msi-irq-cascade-handlers-as-irqf_no_thread.patch