Re: [PATCH] n_tty: Protect minimum_to_wake reset for concurrent readers

From: Peter Hurley
Date: Mon Nov 25 2013 - 12:12:59 EST


On 11/25/2013 11:36 AM, Greg Kroah-Hartman wrote:
On Thu, Nov 07, 2013 at 02:01:57PM -0500, Peter Hurley wrote:
With multiple, concurrent readers (each waiting to acquire the
atomic_read_lock mutex), a departing reader may mistakenly reset
minimum_to_wake after a new reader has already set a new value.

Protect the minimum_to_wake reset with the atomic_read_lock critical
section.

Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
---
drivers/tty/n_tty.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

This patch doesn't apply to Linus's tree anymore (and hence, mine.) Is
it needed for 3.13-final? Or just 3.14-rc1? Either way, can you
refresh it and resend?

Hmmm, for me this applies cleanly to your tty-linus branch:

peter@thor:~/src/kernels/tty$ git tree -10
* c7df628 (HEAD, tty-linus) n_tty: Protect minimum_to_wake reset for concurrent readers
* 3dcf344 (origin/tty-linus) TTY: amiserial, add missing platform check
* dc1dc2f TTY: pmac_zilog, check existence of ports in pmz_console_init()
* c284ee2 n_gsm: race between ld close and gsmtty open
* f301412 tty/serial/8250: fix typo in help text
* c77569d n_tty: Fix 4096-byte canonical reads
* 6f22253 n_tty: Fix echo overrun tail computation
* 42458f4 n_tty: Ensure reader restarts worker for next reader
* 6ce4eac (tag: v3.13-rc1, origin/tty-next, origin/master, origin/HEAD) Linux 3.13-rc1

I'll just resend it.

Regards,
Peter Hurley
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