[PATCH 4.2.y-ckt 088/268] PCI: host: Mark PCIe/PCI (MSI) IRQ cascade handlers as IRQF_NO_THREAD

From: Kamal Mostafa
Date: Wed Jan 27 2016 - 16:40:21 EST

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4.2.8-ckt3 -stable review patch. If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Grygorii Strashko <grygorii.strashko@xxxxxx>

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@xxxxxx

[bhelgaas: add stable tag, fix typos]
Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Acked-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx> (for imx6)
CC: Kishon Vijay Abraham I <kishon@xxxxxx>
CC: Jingoo Han <jingoohan1@xxxxxxxxx>
CC: Kukjin Kim <kgene@xxxxxxxxxx>
CC: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
CC: Richard Zhu <Richard.Zhu@xxxxxxxxxxxxx>
CC: Thierry Reding <thierry.reding@xxxxxxxxx>
CC: Stephen Warren <swarren@xxxxxxxxxxxxx>
CC: Alexandre Courbot <gnurou@xxxxxxxxx>
CC: Simon Horman <horms@xxxxxxxxxxxx>
CC: Pratyush Anand <pratyush.anand@xxxxxxxxx>
CC: Michal Simek <michal.simek@xxxxxxxxxx>
CC: "SÃren Brinkmann" <soren.brinkmann@xxxxxxxxxx>
CC: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>

Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
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(-)

diff --git a/drivers/pci/host/pci-dra7xx.c b/drivers/pci/host/pci-dra7xx.c
index 80db09e..66aa928 100644
--- a/drivers/pci/host/pci-dra7xx.c
+++ b/drivers/pci/host/pci-dra7xx.c
@@ -284,7 +284,8 @@ 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");
diff --git a/drivers/pci/host/pci-exynos.c b/drivers/pci/host/pci-exynos.c
index f9f468d..7b6be77 100644
--- 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(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;
diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
index 233a196..fd5eb2e 100644
--- a/drivers/pci/host/pci-imx6.c
+++ b/drivers/pci/host/pci-imx6.c
@@ -544,7 +544,8 @@ 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;
diff --git a/drivers/pci/host/pci-tegra.c b/drivers/pci/host/pci-tegra.c
index 10c0571..60e3c46 100644
--- a/drivers/pci/host/pci-tegra.c
+++ b/drivers/pci/host/pci-tegra.c
@@ -1289,7 +1289,7 @@ 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);
diff --git a/drivers/pci/host/pcie-rcar.c b/drivers/pci/host/pcie-rcar.c
index c086210..56ce564 100644
--- a/drivers/pci/host/pcie-rcar.c
+++ b/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;
diff --git a/drivers/pci/host/pcie-spear13xx.c b/drivers/pci/host/pcie-spear13xx.c
index 4086268..d877c3b 100644
--- a/drivers/pci/host/pcie-spear13xx.c
+++ b/drivers/pci/host/pcie-spear13xx.c
@@ -282,7 +282,8 @@ 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;
diff --git a/drivers/pci/host/pcie-xilinx.c b/drivers/pci/host/pcie-xilinx.c
index f1a06a0..577fe5b 100644
--- a/drivers/pci/host/pcie-xilinx.c
+++ b/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;
--
1.9.1

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