On 09/01/2015 04:11 PM, Dmitry Vyukov wrote: > The data race is found with KernelThreadSanitizer (on rev 21bdb584af8c): > > ThreadSanitizer: data-race in release_tty > Write of size 8 by thread T325 (K2579): > release_tty+0xf3/0x1c0 drivers/tty/tty_io.c:1688 > tty_release+0x698/0x7c0 drivers/tty/tty_io.c:1920 > __fput+0x15f/0x310 fs/file_table.c:207 > ____fput+0x1d/0x30 fs/file_table.c:243 > task_work_run+0x115/0x130 kernel/task_work.c:123 > do_notify_resume+0x73/0x80 > tracehook_notify_resume include/linux/tracehook.h:190 > do_notify_resume+0x73/0x80 arch/x86/kernel/signal.c:757 > int_signal+0x12/0x17 arch/x86/entry/entry_64.S:326 > Previous read of size 8 by thread T19 (K16): > flush_to_ldisc+0x29/0x300 drivers/tty/tty_buffer.c:472 > process_one_work+0x47e/0x930 kernel/workqueue.c:2036 > worker_thread+0xb0/0x900 kernel/workqueue.c:2170 > kthread+0x150/0x170 kernel/kthread.c:207 > > flush_to_ldisc reads port->itty and checks that it is not NULL, > concurrently release_tty sets port->itty to NULL. It is possible > that flush_to_ldisc loads port->itty once, ensures that it is > not NULL, but then reloads it again and uses. The second load > can already return NULL, which will cause a crash. > > Set port->itty to NULL after shutting down flush_to_ldisc work. > > Signed-off-by: Dmitry Vyukov <dvyu...@google.com> > --- > drivers/tty/tty_io.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c > index 57fc6ee..0df24c1 100644 > --- a/drivers/tty/tty_io.c > +++ b/drivers/tty/tty_io.c > @@ -1684,9 +1684,9 @@ static void release_tty(struct tty_struct *tty, int idx) > tty_free_termios(tty); > tty_driver_remove_tty(tty->driver, tty); > tty->port->itty = NULL; > + cancel_work_sync(&tty->port->buf.work); > if (tty->link) > tty->link->port->itty = NULL; > - cancel_work_sync(&tty->port->buf.work);
This patch doesn't do anything. Regards, Peter Hurley > > tty_kref_put(tty->link); > tty_kref_put(tty); > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
