* Re: [PATCH v2] PCI: endpoint: pci-epf-test: Fix sleeping function being called from atomic context
2025-09-30 2:38 [PATCH v2] PCI: endpoint: pci-epf-test: Fix sleeping function being called from atomic context Bhanu Seshu Kumar Valluri
@ 2025-10-09 5:51 ` Bhanu Seshu Kumar Valluri
2025-10-09 9:37 ` Niklas Cassel
2025-10-13 21:40 ` Bjorn Helgaas
2 siblings, 0 replies; 5+ messages in thread
From: Bhanu Seshu Kumar Valluri @ 2025-10-09 5:51 UTC (permalink / raw)
To: mani, kwilczynski, kishon, bhelgaas, cassel, Frank.Li, dlemoal,
christian.bruel
Cc: linux-pci, linux-kernel, bhanuseshukumar
On 30/09/25 08:08, Bhanu Seshu Kumar Valluri wrote:
> 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 <bhanuseshukumar@gmail.com>
> ---
> 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/20250917161817.15776-1-bhanuseshukumar@gmail.com/
>
> 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(-)
>
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index e091193bd8a8..c9e2eb930ad3 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -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",
Hi,
I just wanted to check if you had a chance to review it or if any changes are needed from my side.
Regards,
Bhanu Seshu Kumar Valluri
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH v2] PCI: endpoint: pci-epf-test: Fix sleeping function being called from atomic context
2025-09-30 2:38 [PATCH v2] PCI: endpoint: pci-epf-test: Fix sleeping function being called from atomic context Bhanu Seshu Kumar Valluri
2025-10-09 5:51 ` Bhanu Seshu Kumar Valluri
@ 2025-10-09 9:37 ` Niklas Cassel
2025-10-13 21:40 ` Bjorn Helgaas
2 siblings, 0 replies; 5+ messages in thread
From: Niklas Cassel @ 2025-10-09 9:37 UTC (permalink / raw)
To: Bhanu Seshu Kumar Valluri
Cc: mani, kwilczynski, kishon, bhelgaas, Frank.Li, dlemoal,
christian.bruel, linux-pci, linux-kernel
On Tue, Sep 30, 2025 at 08:08:09AM +0530, Bhanu Seshu Kumar Valluri wrote:
> 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 <bhanuseshukumar@gmail.com>
> ---
All other calls to pci_epf_test_raise_irq() is done from the workqueue.
While we could change pci_epf_test_doorbell_handler() to queue some work on
the workqueue (and let that work call pci_epf_test_raise_irq()), converting
pci_epf_test_doorbell_handler() to be a threaded IRQ handler seems like the
less invasive change, thus:
Reviewed-by: Niklas Cassel <cassel@kernel.org>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH v2] PCI: endpoint: pci-epf-test: Fix sleeping function being called from atomic context
2025-09-30 2:38 [PATCH v2] PCI: endpoint: pci-epf-test: Fix sleeping function being called from atomic context Bhanu Seshu Kumar Valluri
2025-10-09 5:51 ` Bhanu Seshu Kumar Valluri
2025-10-09 9:37 ` Niklas Cassel
@ 2025-10-13 21:40 ` Bjorn Helgaas
2025-10-14 2:46 ` Bhanu Seshu Kumar Valluri
2 siblings, 1 reply; 5+ messages in thread
From: Bjorn Helgaas @ 2025-10-13 21:40 UTC (permalink / raw)
To: Bhanu Seshu Kumar Valluri
Cc: mani, kwilczynski, kishon, bhelgaas, cassel, Frank.Li, dlemoal,
christian.bruel, linux-pci, linux-kernel
On Tue, Sep 30, 2025 at 08:08:09AM +0530, Bhanu Seshu Kumar Valluri wrote:
> 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 <bhanuseshukumar@gmail.com>
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
> ---
> 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/20250917161817.15776-1-bhanuseshukumar@gmail.com/
>
> 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(-)
>
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index e091193bd8a8..c9e2eb930ad3 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -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",
> --
> 2.34.1
>
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH v2] PCI: endpoint: pci-epf-test: Fix sleeping function being called from atomic context
2025-10-13 21:40 ` Bjorn Helgaas
@ 2025-10-14 2:46 ` Bhanu Seshu Kumar Valluri
0 siblings, 0 replies; 5+ messages in thread
From: Bhanu Seshu Kumar Valluri @ 2025-10-14 2:46 UTC (permalink / raw)
To: Bjorn Helgaas
Cc: mani, kwilczynski, kishon, bhelgaas, cassel, Frank.Li, dlemoal,
christian.bruel, linux-pci, linux-kernel
On 14/10/25 03:10, Bjorn Helgaas wrote:
> 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
>
Hi,
Thanks for the helpful review. I sent a v3 patch to address above review points.
Link to v3: https://lore.kernel.org/all/20251014024109.42287-1-bhanuseshukumar@gmail.com/
Regards,
Bhanu Seshu Kumar Valluri
^ permalink raw reply [flat|nested] 5+ messages in thread