diff mbox series

[net-next,v1,03/21] liquidio: Overcome missing device lock protection in init/remove flows

Message ID 4e78bd8c6f45eef8093547a37c4d00ef0d1fef56.1632565508.git.leonro@nvidia.com (mailing list archive)
State Accepted
Delegated to: Netdev Maintainers
Headers show
Series Move devlink_register to be last devlink command | expand

Checks

Context Check Description
netdev/cover_letter success Link
netdev/fixes_present success Link
netdev/patch_count fail Series longer than 15 patches
netdev/tree_selection success Clearly marked for net-next
netdev/subject_prefix success Link
netdev/cc_maintainers success CCed 6 of 6 maintainers
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 49 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 7 this patch: 7
netdev/header_inline success Link

Commit Message

Leon Romanovsky Sept. 25, 2021, 11:22 a.m. UTC 
From: Leon Romanovsky <leonro@nvidia.com>

The liquidio driver is broken by design. It initialize PCI devices
in separate delayed works. It causes to the situation where device lock
is dropped during initialize and remove sequences.

That lock is part of driver/core and needed to protect from races during
init, destroy and bus invocations.

In addition to lack of locking protection, it has incorrect order of
destroy flows and very questionable synchronization scheme based on
atomic_t.

This change doesn't fix that driver but makes sure that rest of the
netdev subsystem doesn't suffer from such basic protection by adding
device_lock over devlink_*() APIs and by moving devlink_register()
to be last command in setup_nic_devices().

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 .../net/ethernet/cavium/liquidio/lio_main.c   | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/ethernet/cavium/liquidio/lio_main.c b/drivers/net/ethernet/cavium/liquidio/lio_main.c
index a34b3bb2dd4f..dafc79bd34f4 100644
--- a/drivers/net/ethernet/cavium/liquidio/lio_main.c
+++ b/drivers/net/ethernet/cavium/liquidio/lio_main.c
@@ -1279,6 +1279,14 @@  static int liquidio_stop_nic_module(struct octeon_device *oct)
 	struct lio *lio;
 
 	dev_dbg(&oct->pci_dev->dev, "Stopping network interfaces\n");
+	device_lock(&oct->pci_dev->dev);
+	if (oct->devlink) {
+		devlink_unregister(oct->devlink);
+		devlink_free(oct->devlink);
+		oct->devlink = NULL;
+	}
+	device_unlock(&oct->pci_dev->dev);
+
 	if (!oct->ifcount) {
 		dev_err(&oct->pci_dev->dev, "Init for Octeon was not completed\n");
 		return 1;
@@ -1300,12 +1308,6 @@  static int liquidio_stop_nic_module(struct octeon_device *oct)
 	for (i = 0; i < oct->ifcount; i++)
 		liquidio_destroy_nic_device(oct, i);
 
-	if (oct->devlink) {
-		devlink_unregister(oct->devlink);
-		devlink_free(oct->devlink);
-		oct->devlink = NULL;
-	}
-
 	dev_dbg(&oct->pci_dev->dev, "Network interfaces stopped\n");
 	return 0;
 }
@@ -3749,10 +3751,12 @@  static int setup_nic_devices(struct octeon_device *octeon_dev)
 		}
 	}
 
+	device_lock(&octeon_dev->pci_dev->dev);
 	devlink = devlink_alloc(&liquidio_devlink_ops,
 				sizeof(struct lio_devlink_priv),
 				&octeon_dev->pci_dev->dev);
 	if (!devlink) {
+		device_unlock(&octeon_dev->pci_dev->dev);
 		dev_err(&octeon_dev->pci_dev->dev, "devlink alloc failed\n");
 		goto setup_nic_dev_free;
 	}
@@ -3760,9 +3764,10 @@  static int setup_nic_devices(struct octeon_device *octeon_dev)
 	lio_devlink = devlink_priv(devlink);
 	lio_devlink->oct = octeon_dev;
 
-	devlink_register(devlink);
 	octeon_dev->devlink = devlink;
 	octeon_dev->eswitch_mode = DEVLINK_ESWITCH_MODE_LEGACY;
+	devlink_register(devlink);
+	device_unlock(&octeon_dev->pci_dev->dev);
 
 	return 0;