[PATCH net v1] devlink: Don't throw an error if flash notification sent before devlink visible

From: Leon Romanovsky <leonro@nvidia.com>

The mlxsw driver calls to various devlink flash routines even before
users can get any access to the devlink instance itself. For example,
mlxsw_core_fw_rev_validate() one of such functions.

__mlxsw_core_bus_device_register
 -> mlxsw_core_fw_rev_validate
  -> mlxsw_core_fw_flash
   -> mlxfw_firmware_flash
    -> mlxfw_status_notify
     -> devlink_flash_update_status_notify
      -> __devlink_flash_update_notify
       -> WARN_ON(...)

It causes to the WARN_ON to trigger warning about devlink not registered.

Fixes: cf530217408e ("devlink: Notify users when objects are accessible")
Reported-by: Danielle Ratson <redacted>
Tested-by: Danielle Ratson <redacted>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
v1:
 * Used Jakub's suggestion to silently drop flash notifications if
   devlink is not visible yet.
 * Used right person for Reported and Tested tags. 
v0: https://lore.kernel.org/all/1d750b6f4991c16995c4d0927b709eb23647ff85.1636999616.git.leonro@nvidia.com (local)
---
 net/core/devlink.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/core/devlink.c b/net/core/devlink.c
index 5ba4f9434acd..5ad72dbfcd07 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c

@@ -4229,7 +4229,9 @@ static void __devlink_flash_update_notify(struct devlink *devlink,
 	WARN_ON(cmd != DEVLINK_CMD_FLASH_UPDATE &&
 		cmd != DEVLINK_CMD_FLASH_UPDATE_END &&
 		cmd != DEVLINK_CMD_FLASH_UPDATE_STATUS);
-	WARN_ON(!xa_get_mark(&devlinks, devlink->index, DEVLINK_REGISTERED));
+
+	if (!xa_get_mark(&devlinks, devlink->index, DEVLINK_REGISTERED))
+		return;
 
 	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
 	if (!msg)

-- 
2.33.1