linux-sg2042/drivers/tty
Linus Torvalds 55db4c64ed Revert "tty: make receive_buf() return the amout of bytes received"
This reverts commit b1c43f82c5.

It was broken in so many ways, and results in random odd pty issues.

It re-introduced the buggy schedule_work() in flush_to_ldisc() that can
cause endless work-loops (see commit a5660b41af6a: "tty: fix endless
work loop when the buffer fills up").

It also used an "unsigned int" return value fo the ->receive_buf()
function, but then made multiple functions return a negative error code,
and didn't actually check for the error in the caller.

And it didn't actually work at all.  BenH bisected down odd tty behavior
to it:
  "It looks like the patch is causing some major malfunctions of the X
   server for me, possibly related to PTYs.  For example, cat'ing a
   large file in a gnome terminal hangs the kernel for -minutes- in a
   loop of what looks like flush_to_ldisc/workqueue code, (some ftrace
   data in the quoted bits further down).

   ...

   Some more data: It -looks- like what happens is that the
   flush_to_ldisc work queue entry constantly re-queues itself (because
   the PTY is full ?) and the workqueue thread will basically loop
   forver calling it without ever scheduling, thus starving the consumer
   process that could have emptied the PTY."

which is pretty much exactly the problem we fixed in a5660b41af.

Milton Miller pointed out the 'unsigned int' issue.

Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reported-by: Milton Miller <miltonm@bga.com>
Cc: Stefan Bigler <stefan.bigler@keymile.com>
Cc: Toby Gray <toby.gray@realvnc.com>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-06-04 06:33:24 +09:00
..
hvc Fix common misspellings 2011-03-31 11:26:23 -03:00
ipwireless Merge git://git.kernel.org/pub/scm/linux/kernel/git/brodo/pcmcia-2.6 2011-05-24 13:28:35 -07:00
serial Merge branch 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm 2011-05-27 19:51:32 -07:00
vt Revert "tty: make receive_buf() return the amout of bytes received" 2011-06-04 06:33:24 +09:00
Kconfig n_tracerouter and n_tracesink ldisc additions. 2011-05-13 16:31:00 -07:00
Makefile n_tracerouter and n_tracesink ldisc additions. 2011-05-13 16:31:00 -07:00
amiserial.c tty: remove invalid location line in file header 2011-04-19 16:33:36 -07:00
bfin_jtag_comm.c drivers/tty/bfin_jtag_comm.c: avoid calling put_tty_driver on NULL 2011-03-23 19:46:39 -07:00
cyclades.c Merge branch 'trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6 2011-05-26 13:19:00 -07:00
isicom.c tty: move a number of tty drivers from drivers/char/ to drivers/tty/ 2011-02-22 16:14:56 -08:00
moxa.c drivers/tty/moxa.c: Put correct tty value 2011-04-29 14:17:45 -07:00
moxa.h tty: move a number of tty drivers from drivers/char/ to drivers/tty/ 2011-02-22 16:14:56 -08:00
mxser.c tty: move a number of tty drivers from drivers/char/ to drivers/tty/ 2011-02-22 16:14:56 -08:00
mxser.h Fix common misspellings 2011-03-31 11:26:23 -03:00
n_gsm.c Revert "tty: make receive_buf() return the amout of bytes received" 2011-06-04 06:33:24 +09:00
n_hdlc.c Revert "tty: make receive_buf() return the amout of bytes received" 2011-06-04 06:33:24 +09:00
n_r3964.c Revert "tty: make receive_buf() return the amout of bytes received" 2011-06-04 06:33:24 +09:00
n_tracerouter.c n_tracerouter and n_tracesink ldisc additions. 2011-05-13 16:31:00 -07:00
n_tracesink.c n_tracerouter and n_tracesink ldisc additions. 2011-05-13 16:31:00 -07:00
n_tracesink.h n_tracerouter and n_tracesink ldisc additions. 2011-05-13 16:31:00 -07:00
n_tty.c Revert "tty: make receive_buf() return the amout of bytes received" 2011-06-04 06:33:24 +09:00
nozomi.c Merge branch 'trivial' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild-2.6 2011-05-26 13:19:00 -07:00
pty.c tty: remove invalid location line in file header 2011-04-19 16:33:36 -07:00
rocket.c TTY: rocket, remove unused variables 2011-04-19 14:41:48 -07:00
rocket.h tty: move a number of tty drivers from drivers/char/ to drivers/tty/ 2011-02-22 16:14:56 -08:00
rocket_int.h tty: move a number of tty drivers from drivers/char/ to drivers/tty/ 2011-02-22 16:14:56 -08:00
synclink.c tty: remove invalid location line in file header 2011-04-19 16:33:36 -07:00
synclink_gt.c Fix common misspellings 2011-03-31 11:26:23 -03:00
synclinkmp.c Fix common misspellings 2011-03-31 11:26:23 -03:00
sysrq.c lib, arch: add filter argument to show_mem and fix private implementations 2011-03-24 17:49:37 -07:00
tty_audit.c tty_audit: fix tty_audit_add_data live lock on audit disabled 2011-03-07 12:04:50 -08:00
tty_buffer.c Revert "tty: make receive_buf() return the amout of bytes received" 2011-06-04 06:33:24 +09:00
tty_io.c TTY: tty_io, annotate locking functions 2011-04-25 14:19:12 -07:00
tty_ioctl.c Merge branch 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty-2.6 2011-05-23 12:23:20 -07:00
tty_ldisc.c TTY: introduce deinit helpers for proper ldisc shutdown 2011-04-19 14:43:01 -07:00
tty_mutex.c tty: remove invalid location line in file header 2011-04-19 16:33:36 -07:00
tty_port.c