Re: [PATCH] tty: fix data race in n_tty_receive_buf_common

[Kohli, Gaurav]

Hi Alan,
> > > Can you make that code available otherwise it's impossible to see 
> > > what the problem might be.
Âhttps://source.codeaurora.org/quic/la/kernel/msm-4.9/tree/drivers/tty/serial?h=msm-4.9
ÂAs discussed , there not seems a problem as we are getting print 
request even when port seems to closed.


tty_ldisc_lock(tty, 5 * HZ);
Âtty_ldisc_setup(tty);
Âtty_ldisc_unlock(tty)

But in above lock, there is a chance when flush_to_ldisc will occur 
first and acquired a lock in
tty_ldisc_ref itself.
So this may fail, I am not much sure here, Please correct me, If i am 
missing something here.
> So can not we simply return from flush_to_ldisc ,when we know 
> disc_data is not valid like
> we are doing for tty and ldisc already?
>
> if (tty->disc_data == NULL) {
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ tty_ldisc_deref(disc);
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ return;
> ÂÂÂÂÂÂÂ }


Regards
Gaurav
-- Qualcomm India Private Limited, on behalf of Qualcomm Innovation 
Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation 
Collaborative Project.