Re: [PATCH 6/7] n_tty: Fix unsafe update of available buffer space
From: Ilya Zykov <hidden>
Date: 2013-03-19 20:35:48
Also in:
lkml
On 19.03.2013 18:26, Peter Hurley wrote:
receive_room is used to control the amount of data the flip
buffer work can push to the read buffer. This update is unsafe:
CPU 0 | CPU 1
|
| n_tty_read()
| n_tty_set_room()
| left = <calc of space>
n_tty_receive_buf() |
<push data to buffer> |
n_tty_set_room() |
left = <calc of space> |
tty->receive_room = left |
| tty->receive_room = left
receive_room is now updated with a stale calculation of the
available buffer space, and the subsequent work loop will likely
overwrite unread data in the input buffer.Sounds reasonable to me. Thank you. Ilya Zykov [off-list ref]