• Samuel Cabrero's avatar
    cifs: Check for timeout on Negotiate stage · 76e75270
    Samuel Cabrero authored
    Some servers seem to accept connections while booting but never send
    the SMBNegotiate response neither close the connection, causing all
    processes accessing the share hang on uninterruptible sleep state.
    
    This happens when the cifs_demultiplex_thread detects the server is
    unresponsive so releases the socket and start trying to reconnect.
    At some point, the faulty server will accept the socket and the TCP
    status will be set to NeedNegotiate. The first issued command accessing
    the share will start the negotiation (pid 5828 below), but the response
    will never arrive so other commands will be blocked waiting on the mutex
    (pid 55352).
    
    This patch checks for unresponsive servers also on the negotiate stage
    releasing the socket and reconnecting if the response is not received
    and checking again the tcp state when the mutex is acquired.
    
    PID: 55352  TASK: ffff880fd6cc02c0  CPU: 0   COMMAND: "ls"
     #0 [ffff880fd9add9f0] schedule at ffffffff81467eb9
     #1 [ffff880fd9addb38] __mutex_lock_slowpath at ffffffff81468fe0
     #2 [ffff880fd9addba8] mutex_lock at ffffffff81468b1a
     #3 [ffff880fd9addbc0] cifs_reconnect_tcon at ffffffffa042f905 [cifs]
     #4 [ffff880fd9addc60] smb_init at ffffffffa042faeb [cifs]
     #5 [ffff880fd9addca0] CIFSSMBQPathInfo at ffffffffa04360b5 [cifs]
     ....
    
    Which is waiting a mutex owned by:
    
    PID: 5828   TASK: ffff880fcc55e400  CPU: 0   COMMAND: "xxxx"
     #0 [ffff880fbfdc19b8] schedule at ffffffff81467eb9
     #1 [ffff880fbfdc1b00] wait_for_response at ffffffffa044f96d [cifs]
     #2 [ffff880fbfdc1b60] SendReceive at ffffffffa04505ce [cifs]
     #3 [ffff880fbfdc1bb0] CIFSSMBNegotiate at ffffffffa0438d79 [cifs]
     #4 [ffff880fbfdc1c50] cifs_negotiate_protocol at ffffffffa043b383 [cifs]
     #5 [ffff880fbfdc1c80] cifs_reconnect_tcon at ffffffffa042f911 [cifs]
     #6 [ffff880fbfdc1d20] smb_init at ffffffffa042faeb [cifs]
     #7 [ffff880fbfdc1d60] CIFSSMBQFSInfo at ffffffffa0434eb0 [cifs]
     ....
    Signed-off-by: default avatarSamuel Cabrero <scabrero@suse.de>
    Reviewed-by: default avatarAurélien Aptel <aaptel@suse.de>
    Reviewed-by: default avatarRonnie Sahlberg <lsahlber@redhat.com>
    Signed-off-by: default avatarSteve French <smfrench@gmail.com>
    76e75270
cifssmb.c 190 KB