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authorJiri Pirko <jiri@nvidia.com>2023-02-10 13:01:30 +0300
committerDavid S. Miller <davem@davemloft.net>2023-02-13 12:49:14 +0300
commit280f7b2adca09c8d5f34b99f49e5c570aa81daad (patch)
tree3f66d4d8ecf6653b14ef513b5b4ee8045720a625 /net/devlink
parenta72e17b4523223015d3b3fd79bac2b065d6d09a9 (diff)
downloadlinux-280f7b2adca09c8d5f34b99f49e5c570aa81daad.tar.xz
devlink: allow to call devl_param_driverinit_value_get() without holding instance lock
If the driver maintains following basic sane behavior, the devl_param_driverinit_value_get() function could be called without holding instance lock: 1) Driver ensures a call to devl_param_driverinit_value_get() cannot race with registering/unregistering the parameter with the same parameter ID. 2) Driver ensures a call to devl_param_driverinit_value_get() cannot race with devl_param_driverinit_value_set() call with the same parameter ID. 3) Driver ensures a call to devl_param_driverinit_value_get() cannot race with reload operation. By the nature of params usage, these requirements should be trivially achievable. If the driver for some off reason is not able to comply, it has to take the devlink->lock while calling devl_param_driverinit_value_get(). Remove the lock assertion and add comment describing the locking requirements. This fixes a splat in mlx5 driver introduced by the commit referenced in the "Fixes" tag. Lore: https://lore.kernel.org/netdev/719de4f0-76ac-e8b9-38a9-167ae239efc7@amd.com/ Reported-by: Kim Phillips <kim.phillips@amd.com> Fixes: 075935f0ae0f ("devlink: protect devlink param list by instance lock") Signed-off-by: Jiri Pirko <jiri@nvidia.com> Reviewed-by: Simon Horman <simon.horman@corigine.com> Acked-by: Jakub Kicinski <kuba@kernel.org> Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Tested-by: Kim Phillips <kim.phillips@amd.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/devlink')
-rw-r--r--net/devlink/leftover.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/net/devlink/leftover.c b/net/devlink/leftover.c
index c6f0eccc700a..d4c896f89905 100644
--- a/net/devlink/leftover.c
+++ b/net/devlink/leftover.c
@@ -9627,14 +9627,23 @@ EXPORT_SYMBOL_GPL(devlink_params_unregister);
*
* This function should be used by the driver to get driverinit
* configuration for initialization after reload command.
+ *
+ * Note that lockless call of this function relies on the
+ * driver to maintain following basic sane behavior:
+ * 1) Driver ensures a call to this function cannot race with
+ * registering/unregistering the parameter with the same parameter ID.
+ * 2) Driver ensures a call to this function cannot race with
+ * devl_param_driverinit_value_set() call with the same parameter ID.
+ * 3) Driver ensures a call to this function cannot race with
+ * reload operation.
+ * If the driver is not able to comply, it has to take the devlink->lock
+ * while calling this.
*/
int devl_param_driverinit_value_get(struct devlink *devlink, u32 param_id,
union devlink_param_value *val)
{
struct devlink_param_item *param_item;
- lockdep_assert_held(&devlink->lock);
-
if (WARN_ON(!devlink_reload_supported(devlink->ops)))
return -EOPNOTSUPP;