> On 17 Jul 2017, at 13:31, Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > >> On Thu, Jul 13, 2017 at 12:29:54PM +0100, Okash Khawaja wrote: >>> On Wed, Jul 12, 2017 at 07:20:28PM +0100, Alan Cox wrote: >>> >>>> When opening from kernel, we don't use file pointer. The count mismatch >>>> is between tty->count and #fd's. So opening from kernel leads to #fd's >>>> being less than tty->count. I thought this difference is relevant to >>>> user-space opening of tty, and not to kernel opening of tty. Can you >>>> suggest how to address this mismatch? >>> >>> Your kernel reference is the same as having a file open reference so I >>> think this actually needs addressing in the maths. In other words count >>> the number of kernel references and also add that into the test for >>> check_tty_count (kernel references + #fds == count). >>> >>> I'd really like to keep this right because that check has a long history >>> of catching really nasty race conditions in the tty code. The >>> open/close/hangup code is really fragile so worth the debugability. >> >> I see. Okay based this, check_tty_count can be easily updated to take >> into account kernel references. > > Ok, I'll drop this series from my "to-apply" queue and wait for you to > redo it. Sure. I can fix the tty->count mismatch based on Alan's suggestion. However I don't understand why the exclusivity flag should belong to tty_port and not tty_struct. It will be good to know why. Thanks, Okash _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
