[PATCH 1/3] vfio/pci: Drain eventfd RCU callbacks on module exit

[Jiale Yao]

vfio_pci_eventfd_replace_locked() defers freeing replaced eventfds to
vfio_pci_eventfd_rcu_free(). A callback can remain queued after
close_device() returns and the device driver module reference is dropped.
Once the dependent driver is removed, vfio-pci-core can be unloaded while
the callback still points into its module text.

Wait for outstanding RCU callbacks before vfio-pci-core exits.

Fixes: 98693e0897f7 ("vfio/pci: Use RCU for error/request triggers to avoid circular locking")
Signed-off-by: Jiale Yao <yaojiale02@xxxxxxx>
---
 drivers/vfio/pci/vfio_pci_core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 6757054e9d87..9bce419c52c8 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -2675,6 +2675,7 @@ static void vfio_pci_dev_set_try_reset(struct vfio_device_set *dev_set)
 static void vfio_pci_core_cleanup(void)
 {
 	vfio_pci_uninit_perm_bits();
+	rcu_barrier();
 }
 
 static int __init vfio_pci_core_init(void)
-- 
2.34.1