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

[ Upstream commit 8ff0ef9 ]

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/[email protected]

[bhelgaas: add stable tag, fix typos]
Signed-off-by: Grygorii Strashko <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Acked-by: Lucas Stach <[email protected]> (for imx6)
CC: [email protected]
CC: Kishon Vijay Abraham I <[email protected]>
CC: Jingoo Han <[email protected]>
CC: Kukjin Kim <[email protected]>
CC: Krzysztof Kozlowski <[email protected]>
CC: Richard Zhu <[email protected]>
CC: Thierry Reding <[email protected]>
CC: Stephen Warren <[email protected]>
CC: Alexandre Courbot <[email protected]>
CC: Simon Horman <[email protected]>
CC: Pratyush Anand <[email protected]>
CC: Michal Simek <[email protected]>
CC: "Sören Brinkmann" <[email protected]>
CC: Sebastian Andrzej Siewior <[email protected]>

Signed-off-by: Sasha Levin <[email protected]>

Author: grygoriyS

drivers/pci/host/pci-dra7xx.c

@@ -289,7 +289,8 @@ static int __init dra7xx_add_pcie_port(struct dra7xx_pcie *dra7xx,
 	}
 
 	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");

drivers/pci/host/pci-exynos.c

@@ -527,7 +527,8 @@ static int __init exynos_add_pcie_port(struct pcie_port *pp,
 
 		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;

drivers/pci/host/pci-imx6.c

@@ -534,7 +534,8 @@ static int __init imx6_add_pcie_port(struct pcie_port *pp,
 
 		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;

drivers/pci/host/pci-tegra.c

@@ -1304,7 +1304,7 @@ static int tegra_pcie_enable_msi(struct tegra_pcie *pcie)
 
 	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);

drivers/pci/host/pcie-rcar.c

@@ -695,14 +695,16 @@ static int rcar_pcie_enable_msi(struct rcar_pcie *pcie)
 
 	/* 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;

drivers/pci/host/pcie-spear13xx.c

@@ -281,7 +281,8 @@ static int spear13xx_add_pcie_port(struct pcie_port *pp,
 		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;

drivers/pci/host/pcie-xilinx.c

@@ -776,7 +776,8 @@ static int xilinx_pcie_parse_dt(struct xilinx_pcie_port *port)
 
 	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;