Commit 68ea85df authored by Himanshu Madhani's avatar Himanshu Madhani Committed by Thomas Gleixner
Browse files

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: d5124a99 ("PCI/MSI: Provide a sane mechanism for TPH")
Reported-by: default avatarJorge Lopez <jorge.jo.lopez@oracle.com>
Suggested-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarHimanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Tested-by: default avatarJorge Lopez <jorge.jo.lopez@oracle.com>
Link: https://lore.kernel.org/all/20250708222530.1041477-1-himanshu.madhani@oracle.com
parent d7b8f8e2

drivers/pci/msi/msi.c

+3 −1
Original line number Diff line number Diff line
@@ -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