Hi Peter, On 07/12/2015:02:51:16 PM, peter@xxxxxxxxxxxxxxxxxx wrote: > > On Dec 7, 2015, at 7:44 AM, Pratyush Anand <panand@xxxxxxxxxx> wrote: > >> On 07/12/2015:06:54:13 AM, peter@xxxxxxxxxxxxxxxxxx wrote: > >>> On Dec 7, 2015, at 3:50 AM, Pratyush Anand <panand@xxxxxxxxxx> wrote: > >>> > >>> Hi tty experts, > >>> > >>> One of of our application (related to kdump) is failing because of a kernel > >>> change in tty layer. It fails to start "Kdump Vmcore Save Service" because it is > >>> not able to redirect all standard input/output messages to console (exec &> > >>> /dev/console). > >> > >> What device is /dev/console? > > > > Its amba-pl011. > > > >> What device is stdin/stdout? > > > > stdin is not being used in this case. stdout is again serial console > > (amba-pl011). However, if I replace "exec &> /dev/console" with "echo test > > > /dev/console", then also it gets same error. > > Hmm. What's odd is that the race you're observing is only possible when the tty is in final close which isn't true if stdin and stdout and /dev/console all have the same underlying tty device. > > >> When do you observe this failure? > > > > During a early systemd service called after init. > > > > I observe this during kdump operation on seattle platform. When primary kernel > > crashes, kdump loads a secondary kernel and initramfs which copies vmcore(memory > > dump of failed kernel) to the disk for further analysis. It initializes some > > systemd services before starting vmcore copy. One of the early systemd service, > > sets up (mainly) STDOUT to /dev/console, so that copy operation message can be > > viewed. And this operation fails. > > I'm traveling right now but will have a chance to spend time on this Wed. Thanks :-) > > I'm sure patches I already posted on list will address this, but I'd like to make sure the cause is a race on final close, and not some other oversight. I applied "[PATCH v2] Replace tty->closing" series on top of v4.4-rc3, but I am still able to reproduce it. Regards Pratyush -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
