From: Niklas Schnelle Date: Tue, 16 Dec 2025 22:14:03 +0000 (+0100) Subject: PCI/IOV: Fix race between SR-IOV enable/disable and hotplug X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a5338e365c4559d7b4d7356116b0eb95b12e08d5;p=thirdparty%2Fkernel%2Flinux.git PCI/IOV: Fix race between SR-IOV enable/disable and hotplug Commit 05703271c3cd ("PCI/IOV: Add PCI rescan-remove locking when enabling/disabling SR-IOV") tried to fix a race between the VF removal inside sriov_del_vfs() and concurrent hot unplug by taking the PCI rescan/remove lock in sriov_del_vfs(). Similarly the PCI rescan/remove lock was also taken in sriov_add_vfs() to protect addition of VFs. This approach however causes deadlock on trying to remove PFs with SR-IOV enabled because PFs disable SR-IOV during removal and this removal happens under the PCI rescan/remove lock. So the original fix had to be reverted. Instead of taking the PCI rescan/remove lock in sriov_add_vfs() and sriov_del_vfs(), fix the race that occurs with SR-IOV enable and disable vs hotplug higher up in the callchain by taking the lock in sriov_numvfs_store() before calling into the driver's sriov_configure() callback. Fixes: 05703271c3cd ("PCI/IOV: Add PCI rescan-remove locking when enabling/disabling SR-IOV") Reported-by: Benjamin Block Signed-off-by: Niklas Schnelle Signed-off-by: Bjorn Helgaas Reviewed-by: Benjamin Block Reviewed-by: Gerd Bayer Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20251216-revert_sriov_lock-v3-2-dac4925a7621@linux.ibm.com --- diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c index 7de5b18647be..4a659c34935e 100644 --- a/drivers/pci/iov.c +++ b/drivers/pci/iov.c @@ -495,7 +495,9 @@ static ssize_t sriov_numvfs_store(struct device *dev, if (num_vfs == 0) { /* disable VFs */ + pci_lock_rescan_remove(); ret = pdev->driver->sriov_configure(pdev, 0); + pci_unlock_rescan_remove(); goto exit; } @@ -507,7 +509,9 @@ static ssize_t sriov_numvfs_store(struct device *dev, goto exit; } + pci_lock_rescan_remove(); ret = pdev->driver->sriov_configure(pdev, num_vfs); + pci_unlock_rescan_remove(); if (ret < 0) goto exit;