PCI: endpoint: pci-epf-test: Fix sleeping function being called from atomic context

When Root Complex(RC) triggers a Doorbell MSI interrupt to Endpoint(EP) it triggers a warning in the EP. pci_endpoint kselftest target is compiled and used to run the Doorbell test in RC.

[  474.686193] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:271
[  474.710934] Call trace:
[  474.710995]  __might_resched+0x130/0x158
[  474.711011]  __might_sleep+0x70/0x88
[  474.711023]  mutex_lock+0x2c/0x80
[  474.711036]  pci_epc_get_msi+0x78/0xd8
[  474.711052]  pci_epf_test_raise_irq.isra.0+0x74/0x138
[  474.711063]  pci_epf_test_doorbell_handler+0x34/0x50

The BUG arises because the EP's pci_epf_test_doorbell_handler is making an indirect call to pci_epc_get_msi, which uses mutex inside, from interrupt context.

To fix the issue convert hard irq handler to a threaded irq handler to allow it to call functions that can sleep during bottom half execution. Register threaded irq handler with IRQF_ONESHOT to keep interrupt line disabled until the threaded irq handler completes execution.

Fixes eff0c286aa91 ("PCI: endpoint: pci-epf-test: Add doorbell test support")

Signed-off-by Bhanu Seshu Kumar Valluri <[email protected]>

---
Note : It is compiled and tested on TI am642 board.

Change log. V1->V2:
Trimmed Call trace to include only essential calls.
Used 12 digit commit ID in fixes tag.
Steps to reproduce the bug are removed from commit log.
Link to V1: https://lore.kernel.org/all/[email protected]/

Warnings can be reproduced by following steps below. *On EP side:
1. Configure the pci-epf-test function using steps given below mount -t configfs none /sys/kernel/config
cd /sys/kernel/config/pci_ep/
mkdir functions/pci_epf_test/func1
echo 0x104c > functions/pci_epf_test/func1/vendorid echo 0xb010 > functions/pci_epf_test/func1/deviceid echo 32 > functions/pci_epf_test/func1/msi_interrupts echo 2048 > functions/pci_epf_test/func1/msix_interrupts ln -s functions/pci_epf_test/func1 controllers/f102000.pcie-ep/ echo 1 > controllers/f102000.pcie-ep/start

*On RC side:
1. Once EP side configuration is done do pci rescan. echo 1 > /sys/bus/pci/rescan
2. Run Doorbell MSI test using pci_endpoint_test kselftest app. ./pci_endpoint_test -r pcie_ep_doorbell.DOORBELL_TEST
Note: Kernel is compiled with CONFIG_DEBUG_KERNEL enabled.

 drivers/pci/endpoint/functions/pci-epf-test.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

drivers/pci/endpoint/functions/pci-epf-test.c +0 -0

index e091193bd8a8..c9e2eb930ad3 100644

When Root Complex(RC) triggers a Doorbell MSI interrupt to Endpoint(EP) it triggers a warning in the EP. pci_endpoint kselftest target is compiled and used to run the Doorbell test in RC.

[  474.686193] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:271
[  474.710934] Call trace:
[  474.710995]  __might_resched+0x130/0x158
[  474.711011]  __might_sleep+0x70/0x88
[  474.711023]  mutex_lock+0x2c/0x80
[  474.711036]  pci_epc_get_msi+0x78/0xd8
[  474.711052]  pci_epf_test_raise_irq.isra.0+0x74/0x138
[  474.711063]  pci_epf_test_doorbell_handler+0x34/0x50

The BUG arises because the EP's pci_epf_test_doorbell_handler is making an indirect call to pci_epc_get_msi, which uses mutex inside, from interrupt context.

To fix the issue convert hard irq handler to a threaded irq handler to allow it to call functions that can sleep during bottom half execution. Register threaded irq handler with IRQF_ONESHOT to keep interrupt line disabled until the threaded irq handler completes execution.

Fixes eff0c286aa91 ("PCI: endpoint: pci-epf-test: Add doorbell test support")

Signed-off-by Bhanu Seshu Kumar Valluri <[email protected]>

---

When Root Complex(RC) triggers a Doorbell MSI interrupt to Endpoint(EP) it triggers a warning in the EP. pci_endpoint kselftest target is compiled and used to run the Doorbell test in RC.

[  474.686193] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:271
[  474.710934] Call trace:
[  474.710995]  __might_resched+0x130/0x158
[  474.711011]  __might_sleep+0x70/0x88
[  474.711023]  mutex_lock+0x2c/0x80
[  474.711036]  pci_epc_get_msi+0x78/0xd8
[  474.711052]  pci_epf_test_raise_irq.isra.0+0x74/0x138
[  474.711063]  pci_epf_test_doorbell_handler+0x34/0x50

The BUG arises because the EP's pci_epf_test_doorbell_handler is making an indirect call to pci_epc_get_msi, which uses mutex inside, from interrupt context.

To fix the issue convert hard irq handler to a threaded irq handler to allow it to call functions that can sleep during bottom half execution. Register threaded irq handler with IRQF_ONESHOT to keep interrupt line disabled until the threaded irq handler completes execution.

Fixes eff0c286aa91 ("PCI: endpoint: pci-epf-test: Add doorbell test support")

Signed-off-by Bhanu Seshu Kumar Valluri <[email protected]>

---
Note : It is compiled and tested on TI am642 board.

Change log. V1->V2:
Trimmed Call trace to include only essential calls.
Used 12 digit commit ID in fixes tag.
Steps to reproduce the bug are removed from commit log.
Link to V1: https://lore.kernel.org/all/[email protected]/

Warnings can be reproduced by following steps below. *On EP side:
1. Configure the pci-epf-test function using steps given below mount -t configfs none /sys/kernel/config
cd /sys/kernel/config/pci_ep/
mkdir functions/pci_epf_test/func1
echo 0x104c > functions/pci_epf_test/func1/vendorid echo 0xb010 > functions/pci_epf_test/func1/deviceid echo 32 > functions/pci_epf_test/func1/msi_interrupts echo 2048 > functions/pci_epf_test/func1/msix_interrupts ln -s functions/pci_epf_test/func1 controllers/f102000.pcie-ep/ echo 1 > controllers/f102000.pcie-ep/start

*On RC side:
1. Once EP side configuration is done do pci rescan. echo 1 > /sys/bus/pci/rescan
2. Run Doorbell MSI test using pci_endpoint_test kselftest app. ./pci_endpoint_test -r pcie_ep_doorbell.DOORBELL_TEST
Note: Kernel is compiled with CONFIG_DEBUG_KERNEL enabled.

 drivers/pci/endpoint/functions/pci-epf-test.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

drivers/pci/endpoint/functions/pci-epf-test.c +2 -2

index e091193bd8a8..c9e2eb930ad3 100644
@@ -725,8 +725,8 @@ static void pci_epf_test_enable_doorbell(struct pci_epf_test *epf_test,
 	if (bar < BAR_0)
 		goto err_doorbell_cleanup;
 
-	ret = request_irq(epf->db_msg[0].virq, pci_epf_test_doorbell_handler, 0,
-			  "pci-ep-test-doorbell", epf_test);
+	ret = request_threaded_irq(epf->db_msg[0].virq, NULL, pci_epf_test_doorbell_handler,
+				   IRQF_ONESHOT, "pci-ep-test-doorbell", epf_test);
 	if (ret) {
 		dev_err(&epf->dev,
 			"Failed to request doorbell IRQ: %d\n",

Signature · 1 line

2.34.1

Thanks for the fix! It looks like you posted it during the v6.18 merge window, so it was a little bit too late to be included in the v6.18 changes, but it looks like good v6.19 material.

Can you please:

- Rebase to pci/main (v6.18-rc1)
- Add a space before each "("
- Remove the timestamps because they're unnecessary distraction
- Add "()" after function names in commit log
- s/irq/IRQ/
- Rewrap the commit log to fit in 75 columns
- Rewrap the code below to fit in 78 columns because most of the rest of the file does
- Carry Niklas' Reviewed-by when you post the v3