• David Howells's avatar
    rxrpc: Release a call's connection ref on call disconnection · e653cfe4
    David Howells authored
    When a call is disconnected, clear the call's pointer to the connection and
    release the associated ref on that connection.  This means that the call no
    longer pins the connection and the connection can be discarded even before
    the call is.
    As the code currently stands, the call struct is effectively pinned by
    userspace until userspace has enacted a recvmsg() to retrieve the final
    call state as sk_buffs on the receive queue pin the call to which they're
    related because:
     (1) The rxrpc_call struct contains the userspace ID that recvmsg() has to
         include in the control message buffer to indicate which call is being
         referred to.  This ID must remain valid until the terminal packet is
         completely read and must be invalidated immediately at that point as
         userspace is entitled to immediately reuse it.
     (2) The final ACK to the reply to a client call isn't sent until the last
         data packet is entirely read (it's probably worth altering this in
         future to be send the ACK as soon as all the data has been received).
    This change requires a bit of rearrangement to make sure that the call
    isn't going to try and access the connection again after protocol
     (1) Delete the error link earlier when we're releasing the call.  Possibly
         network errors should be distributed via connections at the cost of
         adding in an access to the rxrpc_connection struct.
     (2) Remove the call from the connection's call tree before disconnecting
         the call.  The call tree needs to be removed anyway and incoming
         packets delivered by channel pointer instead.
     (3) The release call event should be considered last after all other
         events have been processed so that we don't need access to the
         connection again.
     (4) Move the channel_lock taking from rxrpc_release_call() to
         rxrpc_disconnect_call() where it will be required in future.
    Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
conn_object.c 16.9 KB