• Dean Jenkins's avatar
    Bluetooth: Remove RFCOMM session refcnt · 08c30aca
    Dean Jenkins authored
    Previous commits have improved the handling of the RFCOMM session
    timer and the RFCOMM session pointers such that freed RFCOMM
    session structures should no longer be erroneously accessed. The
    RFCOMM session refcnt now has no purpose and will be deleted by
    this commit.
    
    Note that the RFCOMM session is now deleted as soon as the
    RFCOMM control channel link is no longer required. This makes the
    lifetime of the RFCOMM session deterministic and absolute.
    Previously with the refcnt, there was uncertainty about when
    the session structure would be deleted because the relative
    refcnt prevented the session structure from being deleted at will.
    
    It was noted that the refcnt could malfunction under very heavy
    real-time processor loading in embedded SMP environments. This
    could cause premature RFCOMM session deletion or double session
    deletion that could result in kernel crashes. Removal of the
    refcnt prevents this issue.
    
    There are 4 connection / disconnection RFCOMM session scenarios:
    host initiated control link ---> host disconnected control link
    host initiated ctrl link ---> remote device disconnected ctrl link
    remote device initiated ctrl link ---> host disconnected ctrl link
    remote device initiated ctrl link ---> remote device disc'ed ctrl link
    
    The control channel connection procedures are independent of the
    disconnection procedures. Strangely, the RFCOMM session refcnt was
    applying special treatment so erroneously combining connection and
    disconnection events. This commit fixes this issue by removing
    some session code that used the "initiator" member of the session
    structure that was intended for use with the data channels.
    Signed-off-by: default avatarDean Jenkins <Dean_Jenkins@mentor.com>
    Acked-by: default avatarMarcel Holtmann <marcel@holtmann.org>
    Signed-off-by: default avatarGustavo Padovan <gustavo.padovan@collabora.co.uk>
    08c30aca
core.c 49.5 KB