From 3cddde484471c602bea04e6f384819d336a1ff84 Mon Sep 17 00:00:00 2001 From: Niklas Schnelle Date: Tue, 16 Dec 2025 23:14:03 +0100 Subject: PCI/IOV: Fix race between SR-IOV enable/disable and hotplug [ Upstream commit a5338e365c4559d7b4d7356116b0eb95b12e08d5 ] 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 Signed-off-by: Sasha Levin --- drivers/pci/iov.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c index 4afd4ee4f7f0..f939cbada375 100644 --- a/drivers/pci/iov.c +++ b/drivers/pci/iov.c @@ -313,7 +313,9 @@ 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; } @@ -325,7 +327,9 @@ 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; -- cgit v1.2.3