[PATCHv2] PCI: xilinx: use fwnode_irq_get() for INTx IRQ lookup

[PATCHv2] PCI: xilinx: use fwnode_irq_get() for INTx IRQ lookup

[Rosen Penev]

Replace irq_of_parse_and_map() with fwnode_irq_get(dev_fwnode(dev), 0)
in xilinx_pcie_parse_dt(). For an OF-backed device this is equivalent to
the previous call, but uses the generic firmware-node API.

Unlike irq_of_parse_and_map(), fwnode_irq_get() returns a positive IRQ or
a negative errno and never 0 (it rewrites 0 to -EINVAL). Store the result
in an int and check for irq < 0, returning the error (including
-EPROBE_DEFER). This also adds the error handling the previous code
lacked, where irq_of_parse_and_map() failures were passed straight into
devm_request_irq().

Built for ARM (multi_v7_defconfig + CONFIG_PCIE_XILINX) with LLVM=1;
drivers/pci/controller/pcie-xilinx.o compiles cleanly.

Assisted-by: opencode:hy3-free
Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 v2: use dev_err_probe to handle EPROBE_DEFER.
 drivers/pci/controller/pcie-xilinx.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/pci/controller/pcie-xilinx.c b/drivers/pci/controller/pcie-xilinx.c
index 4aa139abac16..58532296182f 100644
--- a/drivers/pci/controller/pcie-xilinx.c
+++ b/drivers/pci/controller/pcie-xilinx.c
@@ -20,10 +20,10 @@
 #include <linux/of_address.h>
 #include <linux/of_pci.h>
 #include <linux/of_platform.h>
-#include <linux/of_irq.h>
 #include <linux/pci.h>
 #include <linux/pci-ecam.h>
 #include <linux/platform_device.h>
+#include <linux/property.h>
 
 #include "../pci.h"
 
@@ -535,7 +535,7 @@ static int xilinx_pcie_parse_dt(struct xilinx_pcie *pcie)
 	struct device *dev = pcie->dev;
 	struct device_node *node = dev->of_node;
 	struct resource regs;
-	unsigned int irq;
+	int irq;
 	int err;
 
 	err = of_address_to_resource(node, 0, &regs);
@@ -548,7 +548,10 @@ static int xilinx_pcie_parse_dt(struct xilinx_pcie *pcie)
 	if (IS_ERR(pcie->reg_base))
 		return PTR_ERR(pcie->reg_base);
 
-	irq = irq_of_parse_and_map(node, 0);
+	irq = fwnode_irq_get(dev_fwnode(dev), 0);
+	if (irq < 0)
+		return irq;
+
 	err = devm_request_irq(dev, irq, xilinx_pcie_intr_handler,
 			       IRQF_SHARED | IRQF_NO_THREAD,
 			       "xilinx-pcie", pcie);
@@ -585,10 +588,8 @@ static int xilinx_pcie_probe(struct platform_device *pdev)
 	pcie->dev = dev;
 
 	err = xilinx_pcie_parse_dt(pcie);
-	if (err) {
-		dev_err(dev, "Parsing DT failed\n");
-		return err;
-	}
+	if (err)
+		return dev_err_probe(dev, err, "Parsing DT failed\n");
 
 	xilinx_pcie_init_port(pcie);
 
-- 
2.55.0

Re: [PATCHv2] PCI: xilinx: use fwnode_irq_get() for INTx IRQ lookup

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] The driver requests a shared IRQ before it masks hardware interrupts and before it allocates its IRQ domains, creating a race condition that can lead to an interrupt storm.
--

--- Patch [1]: [PATCHv2] PCI: xilinx: use fwnode_irq_get() for INTx IRQ lookup ---
commit 02b4ee51408c6b762dcc417c028ea4f662761599
Author: Rosen Penev <rosenp@gmail.com>

PCI: xilinx: use fwnode_irq_get() for INTx IRQ lookup

This commit replaces irq_of_parse_and_map() with fwnode_irq_get() for
looking up the INTx IRQ, checking the return value to properly propagate
errors such as -EPROBE_DEFER.

> diff --git a/drivers/pci/controller/pcie-xilinx.c b/drivers/pci/controller/pcie-xilinx.c
> --- a/drivers/pci/controller/pcie-xilinx.c
> +++ b/drivers/pci/controller/pcie-xilinx.c
> @@ -548,7 +548,10 @@ static int xilinx_pcie_parse_dt(struct xilinx_pcie *pcie)
>  	if (IS_ERR(pcie->reg_base))
>  		return PTR_ERR(pcie->reg_base);
>  
> -	irq = irq_of_parse_and_map(node, 0);
> +	irq = fwnode_irq_get(dev_fwnode(dev), 0);
> +	if (irq < 0)
> +		return irq;
> +
>  	err = devm_request_irq(dev, irq, xilinx_pcie_intr_handler,
>  			       IRQF_SHARED | IRQF_NO_THREAD,
>  			       "xilinx-pcie", pcie);

[Severity: High]
This is a pre-existing issue, but does requesting the shared IRQ here
create a race condition?

Looking at xilinx_pcie_probe(), xilinx_pcie_parse_dt() is called before
xilinx_pcie_init_port() masks the hardware interrupts, and before
xilinx_pcie_init_irq_domain() allocates the MSI and legacy IRQ domains.

If the shared IRQ fires before the domains are created,
xilinx_pcie_intr_handler() will execute with pcie->msi_domain and
pcie->leg_domain as NULL.

In that scenario, generic_handle_domain_irq() will return -EINVAL, leaving
the level-triggered interrupt unserviced. Because the handler returns
IRQ_HANDLED, could this immediately re-enter the handler and cause an
unhandled interrupt storm?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260716205811.800920-1-rosenp@gmail.com?part=1