• OGAWA Hirofumi's avatar
    pty: avoid forcing 'low_latency' tty flag · e043e42b
    OGAWA Hirofumi authored
    We really don't want to mark the pty as a low-latency device, because as
    Alan points out, the ->write method can be called from an IRQ (ppp?),
    and that means we can't use ->low_latency=1 as we take mutexes in the
    low_latency case.
    
    So rather than using low_latency to force the written data to be pushed
    to the ldisc handling at 'write()' time, just make the reader side (or
    the poll function) do the flush when it checks whether there is data to
    be had.
    
    This also fixes the problem with lost data in an emacs compile buffer
    (bugzilla 13815), and we can thus revert the low_latency pty hack
    (commit 3a542974: "pty: quickfix for the
    pty ENXIO timing problems").
    Signed-off-by: default avatarOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
    Tested-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
    [ Modified to do the tty_flush_to_ldisc() inside input_available_p() so
      that it triggers for both read and poll()  - Linus]
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    e043e42b
pty.c 18.9 KB