linux-kernel - [PATCH v3] PCI: endpoint: pci-epf-test: Fix sleeping function being called from atomic context

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [day] [month] [year] [list]

Message-Id: <20251014024109.42287-1-bhanuseshukumar@gmail.com>
Date: Tue, 14 Oct 2025 08:11:09 +0530
From: Bhanu Seshu Kumar Valluri <bhanuseshukumar@...il.com>
To: Manivannan Sadhasivam <mani@...nel.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	Kishon Vijay Abraham I <kishon@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Niklas Cassel <cassel@...nel.org>,
	Frank Li <Frank.Li@....com>,
	Damien Le Moal <dlemoal@...nel.org>,
	Mohamed Khalfella <khalfella@...il.com>,
	Christian Bruel <christian.bruel@...s.st.com>
Cc: linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	khalid@...nel.org,
	linux-kernel-mentees@...ts.linuxfoundation.org,
	skhan@...uxfoundation.org,
	david.hunter.linux@...il.com,
	bhanuseshukumar@...il.com
Subject: [PATCH v3] 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.

BUG: sleeping function called from invalid context at kernel/locking/mutex.c:271
Call trace:
 __might_resched+0x130/0x158
 __might_sleep+0x70/0x88
 mutex_lock+0x2c/0x80
 pci_epc_get_msi+0x78/0xd8
 pci_epf_test_raise_irq.isra.0+0x74/0x138
 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@...il.com>
Reviewed-by: Niklas Cassel <cassel@...nel.org>
---
 Note : The patch is compiled and tested on TI am642 board.

 Change log
 V2->V3:
  Addressed Bjorn Helgass review points in v2
  - 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
  Link to V2: https://lore.kernel.org/all/20250930023809.7931-1-bhanuseshukumar@gmail.com/

 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/

 drivers/pci/endpoint/functions/pci-epf-test.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
index 31617772a..b05e8db57 100644
--- a/drivers/pci/endpoint/functions/pci-epf-test.c
+++ b/drivers/pci/endpoint/functions/pci-epf-test.c
@@ -730,8 +730,9 @@ 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