tree 6cf78a3f0de9811bdc30739ccd01a4db6c4b3baf
parent a59c0d6f14315a3f300f6f3786137213727e4c47
author Joe Peterson <joe@skyrush.com> 1230903812 +0000
committer Linus Torvalds <torvalds@linux-foundation.org> 1230920377 -0800

n_tty: Fix hanfling of buffer full corner cases

Fix the handling of input characters when the tty buffer is full or nearly
full.  This includes tests that are done in n_tty_receive_char() and handling
of PARMRK.

Problems with the buffer-full tests done in receive_char() caused characters to
be lost at times when the buffer(s) filled.  Also, these full conditions
would often only be detected with echo on, and PARMRK was not accounted for
properly in all cases.  One symptom of these problems, in addition to lost
characters, was early termination from unix commands like tr and cat when
^Q was used to break from a stopped tty with full buffers (note that breaking
out was often previously not possible, due to the pty getting in "gridlock",
which will be addressed in another patch).  Note space is always reserved
at the end of the buffer for a newline (or EOF/EOL) in canonical mode.

Signed-off-by: Joe Peterson <joe@skyrush.com>
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>