• David Brownell's avatar
    USB: ohci - record data toggle after unlink · 29c8f6a7
    David Brownell authored
    This patch fixes a problem with OHCI where canceling bulk or
    interrupt URBs may lose track of the right data toggle.  This
    seems to be a longstanding bug, possibly dating back to the
    Linux 2.4 kernel, which stayed hidden because
     (a) about half the time the data toggle bit was correct;
     (b) canceling such URBs is unusual; and
     (c) the few drivers which cancel these URBs either
          [1] do it only as part of shutting down, or
          [2] have fault recovery logic, which recovers.
    For those transfer types, the toggle is normally written back
    into the ED when each TD is retired.  But canceling bypasses
    the mechanism used to retire TDs ... so on average, half the
    time the toggle bit will be invalid after cancelation.
    The fix is simple:  the toggle state of any canceled TDs are
    propagated back to the ED in the finish_unlinks function.
    (Issue found by leonidv11@gmail.com ...)
    Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
    Cc: Leonid <leonidv11@gmail.com>
    Cc: stable <stable@kernel.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
ohci-q.c 31.3 KB