linux/drivers/tty
Francesco Ruggeri c4dc304677 tty: Fix pty master poll() after slave closes v2
Commit f95499c303 ("n_tty: Don't wait for buffer work in read() loop")
introduces a race window where a pty master can be signalled that the pty
slave was closed before all the data that the slave wrote is delivered.
Commit f8747d4a46 ("tty: Fix pty master read() after slave closes") fixed the
problem in case of n_tty_read, but the problem still exists for n_tty_poll.
This can be seen by running 'for ((i=0; i<100;i++));do ./test.py ;done'
where test.py is:

import os, select, pty

(pid, pty_fd) = pty.fork()

if pid == 0:
   os.write(1, 'This string should be received by parent')
else:
   poller = select.epoll()
   poller.register( pty_fd, select.EPOLLIN )
   ready = poller.poll( 1 * 1000 )
   for fd, events in ready:
      if not events & select.EPOLLIN:
         print 'missed POLLIN event'
      else:
         print os.read(fd, 100)
   poller.close()

The string from the slave is missed several times.
This patch takes the same approach as the fix for read and special cases
this condition for poll.
Tested on 3.16.

Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-11-06 12:23:36 -08:00
..
hvc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux 2014-10-11 20:34:00 -04:00
ipwireless tty: ipwireless: Remove tty->closing abort from ipw_open() 2014-07-10 16:06:49 -07:00
serial serial: of-serial: fix uninitialized kmalloc variable 2014-11-05 20:12:02 -08:00
vt tty/vt: don't set font mappings on vc not supporting this 2014-11-05 20:12:02 -08:00
amiserial.c tty/amiserial: avoid interruptible_sleep_on 2014-01-07 17:05:21 -08:00
bfin_jtag_comm.c sched, cleanup, treewide: Remove set_current_state(TASK_RUNNING) after schedule() 2014-09-19 12:35:17 +02:00
cyclades.c tty: Remove tty_hung_up_p() tests from tty drivers' open() 2014-07-10 16:06:49 -07:00
ehv_bytechan.c tty: Update hypervisor tty drivers to use core stdout parsing code. 2014-06-26 17:12:23 +01:00
goldfish.c goldfish: clean up the checkpatch warnings 2014-05-15 13:20:42 -07:00
isicom.c TTY: switch tty_flip_buffer_push 2013-01-15 22:30:15 -08:00
Kconfig drivers/tty: ehv_bytechan fails to build as a module 2014-01-09 17:52:12 -06:00
Makefile tty: Add timed, writer-prioritized rw semaphore 2013-05-20 12:30:32 -07:00
metag_da.c tty/metag_da: Add console_poll module parameter 2014-09-28 21:35:56 -04:00
moxa.c TTY: fix decimal printf format specifiers prefixed with 0x 2014-09-08 15:51:35 -07:00
moxa.h
mxser.c tty: mxser: Fix build warning introduced by dfc7b837c7 (Re: linux-next: build warning after merge of the tty.current tree) 2013-05-22 10:26:02 -07:00
mxser.h
n_gsm.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-08-06 09:38:14 -07:00
n_hdlc.c drivers/tty/n_hdlc.c: replace kmalloc/memset by kzalloc 2014-05-28 13:33:18 -07:00
n_r3964.c tty: Always handle NULL flag ptr 2013-12-08 16:56:05 -08:00
n_tracerouter.c
n_tracesink.c
n_tracesink.h
n_tty.c tty: Fix pty master poll() after slave closes v2 2014-11-06 12:23:36 -08:00
nozomi.c drivers/tty/nozomi.c: Use 'nozomi_setup_memory' instead of 'setup_memory' 2014-09-08 16:09:23 -07:00
pty.c tty: Move packet mode flow control notifications to pty driver 2014-09-23 21:19:35 -07:00
rocket_int.h
rocket.c tty: remove DEFINE_PCI_DEVICE_TABLE macro 2013-12-08 17:09:07 -08:00
rocket.h
synclink_gt.c synclink_gt: use pci_zalloc_consistent 2014-08-08 15:57:30 -07:00
synclink.c tty: Remove tty_hung_up_p() tests from tty drivers' open() 2014-07-10 16:06:49 -07:00
synclinkmp.c tty: Remove tty_hung_up_p() tests from tty drivers' open() 2014-07-10 16:06:49 -07:00
sysrq.c mm, oom: ensure memoryless node zonelist always includes zones 2014-08-06 18:01:21 -07:00
tty_audit.c audit: anchor all pid references in the initial pid namespace 2014-03-20 10:11:55 -04:00
tty_buffer.c Staging: speakup: Update __speakup_paste_selection() tty (ab)usage to match vt 2014-05-24 02:25:11 +09:00
tty_io.c tty: Prevent "read/write wait queue active!" log flooding 2014-11-05 16:14:09 -08:00
tty_ioctl.c tty: Hold termios_rwsem for tcflow(TCIxxx) 2014-09-23 21:19:36 -07:00
tty_ldisc.c tty: delete non-required instances of include <linux/init.h> 2014-01-07 17:05:21 -08:00
tty_ldsem.c lockdep: Make held_lock->check and "int check" argument bool 2014-02-09 21:18:54 +01:00
tty_mutex.c tty: tty_mutex.c: Fixed coding style warning (using printk) 2012-10-24 11:34:51 -07:00
tty_port.c tty: Remove tty_hung_up_p() tests from tty drivers' open() 2014-07-10 16:06:49 -07:00