Re: [PATCH v2] tty: fix stall caused by missing memory barrier in drivers/tty/n_tty.c

2015-10-09 Thread Kosuke Tatsukawa
Peter Hurley wrote: > On 10/09/2015 01:28 PM, Peter Hurley wrote: >> Tatsukawa-san, >> >> I would still like to root-cause the reported stall; is the reported >> stall resolved if smp_mb() is added before the waitqueue_active() >> in __receive_buf()? > > Nevermind, I see it now. > > The store to

Re: [PATCH v2] tty: fix stall caused by missing memory barrier in drivers/tty/n_tty.c

2015-10-09 Thread Peter Hurley
On 10/09/2015 01:28 PM, Peter Hurley wrote: > Tatsukawa-san, > > I would still like to root-cause the reported stall; is the reported > stall resolved if smp_mb() is added before the waitqueue_active() > in __receive_buf()? Nevermind, I see it now. The store to commit_head is deferred until

Re: [PATCH v2] tty: fix stall caused by missing memory barrier in drivers/tty/n_tty.c

2015-10-09 Thread Peter Hurley
On 10/02/2015 04:27 AM, Kosuke Tatsukawa wrote: > My colleague ran into a program stall on a x86_64 server, where > n_tty_read() was waiting for data even if there was data in the buffer > in the pty. kernel stack for the stuck process looks like below. > #0 [88303d107b58] __schedule at

Re: [PATCH v2] tty: fix stall caused by missing memory barrier in drivers/tty/n_tty.c

2015-10-09 Thread Peter Hurley
On 10/02/2015 04:27 AM, Kosuke Tatsukawa wrote: > My colleague ran into a program stall on a x86_64 server, where > n_tty_read() was waiting for data even if there was data in the buffer > in the pty. kernel stack for the stuck process looks like below. > #0 [88303d107b58] __schedule at

Re: [PATCH v2] tty: fix stall caused by missing memory barrier in drivers/tty/n_tty.c

2015-10-09 Thread Kosuke Tatsukawa
Peter Hurley wrote: > On 10/09/2015 01:28 PM, Peter Hurley wrote: >> Tatsukawa-san, >> >> I would still like to root-cause the reported stall; is the reported >> stall resolved if smp_mb() is added before the waitqueue_active() >> in __receive_buf()? > > Nevermind, I see it now. > > The store to

Re: [PATCH v2] tty: fix stall caused by missing memory barrier in drivers/tty/n_tty.c

2015-10-09 Thread Peter Hurley
On 10/09/2015 01:28 PM, Peter Hurley wrote: > Tatsukawa-san, > > I would still like to root-cause the reported stall; is the reported > stall resolved if smp_mb() is added before the waitqueue_active() > in __receive_buf()? Nevermind, I see it now. The store to commit_head is deferred until

Re: [PATCH v2] tty: fix stall caused by missing memory barrier in drivers/tty/n_tty.c

2015-10-09 Thread Peter Hurley
On 10/02/2015 04:27 AM, Kosuke Tatsukawa wrote: > My colleague ran into a program stall on a x86_64 server, where > n_tty_read() was waiting for data even if there was data in the buffer > in the pty. kernel stack for the stuck process looks like below. > #0 [88303d107b58] __schedule at

Re: [PATCH v2] tty: fix stall caused by missing memory barrier in drivers/tty/n_tty.c

2015-10-09 Thread Peter Hurley
On 10/02/2015 04:27 AM, Kosuke Tatsukawa wrote: > My colleague ran into a program stall on a x86_64 server, where > n_tty_read() was waiting for data even if there was data in the buffer > in the pty. kernel stack for the stuck process looks like below. > #0 [88303d107b58] __schedule at

[PATCH v2] tty: fix stall caused by missing memory barrier in drivers/tty/n_tty.c

2015-10-02 Thread Kosuke Tatsukawa
My colleague ran into a program stall on a x86_64 server, where n_tty_read() was waiting for data even if there was data in the buffer in the pty. kernel stack for the stuck process looks like below. #0 [88303d107b58] __schedule at 815c4b20 #1 [88303d107bd0] schedule at

[PATCH v2] tty: fix stall caused by missing memory barrier in drivers/tty/n_tty.c

2015-10-02 Thread Kosuke Tatsukawa
My colleague ran into a program stall on a x86_64 server, where n_tty_read() was waiting for data even if there was data in the buffer in the pty. kernel stack for the stuck process looks like below. #0 [88303d107b58] __schedule at 815c4b20 #1 [88303d107bd0] schedule at