Re: [PATCH V1] tty: fix data race between tty_init_dev and flush of buf

[Alan Cox]

On Wed, 17 Jan 2018 18:54:19 +0530
Gaurav Kohli <gkohli@xxxxxxxxxxxxxx> wrote:

> There can be a race, if receive_buf call comes before
> tty initialization completes in n_tty_open and tty->disc_data
> may be NULL.
> 
> CPU0					CPU1
> ----					----
>  000|n_tty_receive_buf_common()   	n_tty_open()
> -001|n_tty_receive_buf2()		tty_ldisc_open.isra.3()
> -002|tty_ldisc_receive_buf(inline)	tty_ldisc_setup()
> 
> Using ldisc semaphore lock in tty_init_dev till disc_data
> initializes completely.
> 
> Signed-off-by: Gaurav Kohli <gkohli@xxxxxxxxxxxxxx>

Reviewed-by: Alan Cox <alan@xxxxxxxxxxxxxxx>

Alan