[PATCH v2 vfio 1/3] pds/vfio: Fix spinlock bad magic BUG

From: Brett Creeley
Date: Wed Oct 11 2023 - 19:01:43 EST


The following BUG was found when running on a kernel with
CONFIG_DEBUG_SPINLOCK=y set:

BUG: spinlock bad magic on CPU#2, bash/2481
lock: 0xffff8d6052a88f50, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
Call Trace:
<TASK>
dump_stack_lvl+0x36/0x50
do_raw_spin_lock+0x79/0xc0
pds_vfio_reset+0x1d/0x60 [pds_vfio_pci]
pci_reset_function+0x4b/0x70
reset_store+0x5b/0xa0
kernfs_fop_write_iter+0x137/0x1d0
vfs_write+0x2de/0x410
ksys_write+0x5d/0xd0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x6e/0xd8

As shown, the .magic: 00000000, does not match the expected value. This
is because spin_lock_init() is never called for the reset_lock. Fix
this by calling spin_lock_init(&pds_vfio->reset_lock) when initializing
the device.

Signed-off-by: Brett Creeley <brett.creeley@xxxxxxx>
Reviewed-by: Shannon Nelson <shannon.nelson@xxxxxxx>
---
drivers/vfio/pci/pds/vfio_dev.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/vfio/pci/pds/vfio_dev.c b/drivers/vfio/pci/pds/vfio_dev.c
index 649b18ee394b..c351f588fa13 100644
--- a/drivers/vfio/pci/pds/vfio_dev.c
+++ b/drivers/vfio/pci/pds/vfio_dev.c
@@ -155,6 +155,8 @@ static int pds_vfio_init_device(struct vfio_device *vdev)

pds_vfio->vf_id = vf_id;

+ spin_lock_init(&pds_vfio->reset_lock);
+
vdev->migration_flags = VFIO_MIGRATION_STOP_COPY | VFIO_MIGRATION_P2P;
vdev->mig_ops = &pds_vfio_lm_ops;
vdev->log_ops = &pds_vfio_log_ops;
--
2.17.1