linux/fs/smb
Shyam Prasad N 5eef12c4e3 cifs: fix lock ordering while disabling multichannel
The code to handle the case of server disabling multichannel
was picking iface_lock with chan_lock held. This goes against
the lock ordering rules, as iface_lock is a higher order lock
(even if it isn't so obvious).

This change fixes the lock ordering by doing the following in
that order for each secondary channel:
1. store iface and server pointers in local variable
2. remove references to iface and server in channels
3. unlock chan_lock
4. lock iface_lock
5. dec ref count for iface
6. unlock iface_lock
7. dec ref count for server
8. lock chan_lock again

Since this function can only be called in smb2_reconnect, and
that cannot be called by two parallel processes, we should not
have races due to dropping chan_lock between steps 3 and 8.

Fixes: ee1d21794e ("cifs: handle when server stops supporting multichannel")
Reported-by: Paulo Alcantara <pc@manguebit.com>
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
2023-11-14 11:39:35 -06:00
..
client cifs: fix lock ordering while disabling multichannel 2023-11-14 11:39:35 -06:00
common Add definition for new smb3.1.1 command type 2023-10-30 09:57:03 -05:00
server ksmbd: handle malformed smb1 message 2023-11-07 18:54:25 -06:00
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