[PATCH net v4] devlink: use direct firmware requests for flash updates

request_firmware() may enter the sysfs fallback and call
try_to_freeze(). Devlink invokes it while holding the instance lock,
causing syzbot to report:

  WARNING: syz-executor/... still has locks held!

Firmware flash requests already name a file provided by userspace.
Use request_firmware_direct() in both flash update paths so a missing
file fails immediately instead of entering the sysfs fallback. This
keeps the normal devlink locking intact.

On systems with CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y, devlink flash
can no longer obtain a missing image through that fallback. Callers still
receive the existing error result, and netlink users retain the extack
message.

Fixes: b44cfd4f5b91 ("devlink: move request_firmware out of driver")
Reported-by: syzbot+372a7d84708b07f64d9b@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=372a7d84708b07f64d9b
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Miguel Garcia <redacted>
---
Changes in v4:
- Resend as a new thread so patchwork and CI pick up the new revision.

Changes in v3:
- Use request_firmware_direct() instead of dropping the devlink instance
  lock, as suggested by Jakub Kicinski.
- Document the resulting sysfs fallback behavior.
- Rebase onto net/main at bc93419130bb.

Changes in v2:
- Cc Jacob Keller, author of b44cfd4f5b91, as requested by Andrew Lunn.
- Keep only b44cfd4f5b91 as the Fixes tag; ed539ba614a0 provides the
  registration check but did not introduce the locking bug.

v3: https://lore.kernel.org/r/20260901123819.2035064-1-miguelgarciaroman8@gmail.com (local)
v2: https://lore.kernel.org/r/20260830111700.1799255-1-miguelgarciaroman8@gmail.com (local)
v1: https://lore.kernel.org/r/20260829142525.3900565-1-miguelgarciaroman8@gmail.com (local)

 net/devlink/dev.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/devlink/dev.c b/net/devlink/dev.c
index 55959b0ff..b85bb02a9 100644
--- a/net/devlink/dev.c
+++ b/net/devlink/dev.c

@@ -1169,7 +1169,7 @@ int devlink_nl_flash_update_doit(struct sk_buff *skb, struct genl_info *info)
 
 	nla_file_name = info->attrs[DEVLINK_ATTR_FLASH_UPDATE_FILE_NAME];
 	file_name = nla_data(nla_file_name);
-	ret = request_firmware(&params.fw, file_name, devlink->dev);
+	ret = request_firmware_direct(&params.fw, file_name, devlink->dev);
 	if (ret) {
 		NL_SET_ERR_MSG_ATTR(info->extack, nla_file_name,
 				    "failed to locate the requested firmware file");

@@ -1245,7 +1245,7 @@ int devlink_compat_flash_update(struct devlink *devlink, const char *file_name)
 		goto out_unlock;
 	}
 
-	ret = request_firmware(&params.fw, file_name, devlink->dev);
+	ret = request_firmware_direct(&params.fw, file_name, devlink->dev);
 	if (ret)
 		goto out_unlock;
 

-- 
2.43.0