The n2 field is settable but didn't get propogated
Signed-off-by: Ken Mills <ken.k.mills@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Kay Sievers pointed out that usage of POLLIN is well defined by POSIX,
and the current usage here doesn't follow that definition. So let's
duplicate the same semantics as implemented by sysfs_poll() instead.
Signed-off-by: Nicolas Pitre <nicolas.pitre@canonical.com>
Acked-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
A kernel BUG when bluetooth rfcomm connection drop while the associated
serial port is open is sometime triggered.
It seems that the line discipline can disappear between the
tty_ldisc_put and tty_ldisc_get. This patch fall back to the N_TTY line
discipline if the previous discipline is not available anymore.
Signed-off-by: Philippe Retornaz <philippe.retornaz@epfl.ch>
Acked-by: Alan Cox <alan@linux.intel.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
It was removed in 65b770468e (tty-ldisc: turn ldisc user count into
a proper refcount), but we need to wait for last user to quit the
ldisc before we close it in tty_set_ldisc.
Otherwise weird things start to happen. There might be processes
waiting in tty_read->n_tty_read on tty->read_wait for input to appear
and at that moment, a change of ldisc is fatal. n_tty_close is called,
it frees read_buf and the waiting process is still in the middle of
reading and goes nuts after it is woken.
Previously we prevented close to happen when others are in ldisc ops
by tty_ldisc_wait_idle in tty_set_ldisc. But the commit above removed
that. So revoke the change and test whether there is 1 user (=we), and
allow the close then.
We can do that without ldisc/tty locks, because nobody else can open
the device due to TTY_LDISC_CHANGING bit set, so we in fact wait for
everybody to leave.
I don't understand why tty_ldisc_lock would be needed either when the
counter is an atomic variable, so this is a lockless
tty_ldisc_wait_idle.
On the other hand, if we fail to wait (timeout or signal), we have to
reenable the halted ldiscs, so we take ldisc lock and reuse the setup
path at the end of tty_set_ldisc.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: Sebastian Andrzej Siewior <bigeasy@breakpoint.cc>
LKML-Reference: <20101031104136.GA511@Chamillionaire.breakpoint.cc>
LKML-Reference: <1287669539-22644-1-git-send-email-jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Cc: stable@kernel.org [32, 33, 36]
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
There's a small window inside the flush_to_ldisc function,
where the tty is unlocked and calling ldisc's receive_buf
function. If in this window new buffer is added to the tty,
the processing might never leave the flush_to_ldisc function.
This scenario will hog the cpu, causing other tty processing
starving, and making it impossible to interface the computer
via tty.
I was able to exploit this via pty interface by sending only
control characters to the master input, causing the flush_to_ldisc
to be scheduled, but never actually generate any output.
To reproduce, please run multiple instances of following code.
- SNIP
#define _XOPEN_SOURCE
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int main(int argc, char **argv)
{
int i, slave, master = getpt();
char buf[8192];
sprintf(buf, "%s", ptsname(master));
grantpt(master);
unlockpt(master);
slave = open(buf, O_RDWR);
if (slave < 0) {
perror("open slave failed");
return 1;
}
for(i = 0; i < sizeof(buf); i++)
buf[i] = rand() % 32;
while(1) {
write(master, buf, sizeof(buf));
}
return 0;
}
- SNIP
The attached patch (based on -next tree) fixes this by checking on the
tty buffer tail. Once it's reached, the current work is rescheduled
and another could run.
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: stable <stable@kernel.org>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The autogenerated files (consolemap_deftbl.c and defkeymap.c) need to
be ignored by git, so move the .gitignore file that was doing it to the
properly location now that the files have moved as well.
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The vt and other related code is moved into the drivers/tty/vt directory.
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The tty code should be in its own subdirectory and not in the char
driver with all of the cruft that is currently there.
Based on work done by Arnd Bergmann <arnd@arndb.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Ken Mills