From 68ea85df15d111d82fc474cbe104174791169355 Mon Sep 17 00:00:00 2001 From: Himanshu Madhani Date: Tue, 8 Jul 2025 22:25:30 +0000 Subject: [PATCH] PCI/MSI: Prevent recursive locking in pci_msix_write_tph_tag() pci_msix_write_tph_tag() takes the per device MSI descriptor mutex and then invokes msi_domain_get_virq(), which takes the same mutex again. That obviously results in a system hang which is exposed by a softlockup or lockdep warning. Move the lock guard after the invocation of msi_domain_get_virq() to fix this. [ tglx: Massage changelog by adding a proper explanation and removing the not really useful stacktrace ] Fixes: d5124a9957b2 ("PCI/MSI: Provide a sane mechanism for TPH") Reported-by: Jorge Lopez Suggested-by: Thomas Gleixner Signed-off-by: Himanshu Madhani Signed-off-by: Thomas Gleixner Tested-by: Jorge Lopez Link: https://lore.kernel.org/all/20250708222530.1041477-1-himanshu.madhani@oracle.com --- drivers/pci/msi/msi.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/pci/msi/msi.c b/drivers/pci/msi/msi.c index 6ede55a7c5e65..d686488f4111d 100644 --- a/drivers/pci/msi/msi.c +++ b/drivers/pci/msi/msi.c @@ -934,10 +934,12 @@ int pci_msix_write_tph_tag(struct pci_dev *pdev, unsigned int index, u16 tag) if (!pdev->msix_enabled) return -ENXIO; - guard(msi_descs_lock)(&pdev->dev); virq = msi_get_virq(&pdev->dev, index); if (!virq) return -ENXIO; + + guard(msi_descs_lock)(&pdev->dev); + /* * This is a horrible hack, but short of implementing a PCI * specific interrupt chip callback and a huge pile of -- 2.47.2