Opening the slave BSD pty first already returns -EIO from the slave pty_open(), which in turn causes the newly installed tty pair to be released before returning from tty_open(). However, this can also cause a parallel master BSD pty open to fail because the pty pair destruction may already been taking place in tty_release(). Failing at driver->install() if the slave pty is opened first ensures that a pty master open cannot fail, because the driver tables will not have been updated so tty_driver_lookup_tty() won't find the master pty (and attempt to "re-open" it). In turn, this guarantees that any tty with a tty->count == 0 is in final close (rather than never opened). Reviewed-by: Alan Cox <alan@xxxxxxxxxxxxxxx> Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx> --- drivers/tty/pty.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c index 7a1a538..bdb8fd1 100644 --- a/drivers/tty/pty.c +++ b/drivers/tty/pty.c @@ -383,6 +383,10 @@ static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty, int idx = tty->index; int retval = -ENOMEM; + /* Opening the slave first has always returned -EIO */ + if (driver->subtype != PTY_TYPE_MASTER) + return -EIO; + ports[0] = kmalloc(sizeof **ports, GFP_KERNEL); ports[1] = kmalloc(sizeof **ports, GFP_KERNEL); if (!ports[0] || !ports[1]) @@ -419,8 +423,6 @@ static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty, * Everything allocated ... set up the o_tty structure. */ tty_driver_kref_get(driver->other); - if (driver->subtype == PTY_TYPE_MASTER) - o_tty->count++; /* Establish the links in both directions */ tty->link = o_tty; o_tty->link = tty; @@ -432,6 +434,7 @@ static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty, tty_driver_kref_get(driver); tty->count++; + o_tty->count++; return 0; err_free_termios: if (legacy) -- 2.1.3 -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
