Re: [PATCH 18/19] staging: lustre: replace l_wait_event_exclusive_head() with wait_event_idle_exclusive

James Simmons
2018-01-17T15:36:28Z

> This l_wait_event_exclusive_head() will wait indefinitely
> if the timeout is zero. If it does wait with a timeout
> and times out, the timeout for next time is set to zero.
>
> The can be mapped to a call to either
> wait_event_idle_exclusive()
> or
> wait_event_idle_exclusive_timeout()
> depending in the timeout setting.
>
> The current code arrange for LIFO queuing of waiters,
> but include/event.h doesn't support that yet.
> Until it does, fall back on FIFO with
> wait_event_idle_exclusive{,_timeout}().

Reviewed-by: James Simmons <jsimmons@infradead.org>

> Signed-off-by: NeilBrown <neilb@suse.com>
> ---
> drivers/staging/lustre/lustre/ptlrpc/service.c | 43 ++++++++++++++----------
> 1 file changed, 25 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/staging/lustre/lustre/ptlrpc/service.c b/drivers/staging/lustre/lustre/ptlrpc/service.c
> index 6e3403417434..29fdb54f16ca 100644
> --- a/drivers/staging/lustre/lustre/ptlrpc/service.c
> +++ b/drivers/staging/lustre/lustre/ptlrpc/service.c
> @@ -1897,15 +1897,6 @@ ptlrpc_check_rqbd_pool(struct ptlrpc_service_part *svcpt)
> }
> }
>
> -static int
> -ptlrpc_retry_rqbds(void *arg)
> -{
> - struct ptlrpc_service_part *svcpt = arg;
> -
> - svcpt->scp_rqbd_timeout = 0;
> - return -ETIMEDOUT;
> -}
> -
> static inline int
> ptlrpc_threads_enough(struct ptlrpc_service_part *svcpt)
> {
> @@ -1968,13 +1959,17 @@ ptlrpc_server_request_incoming(struct ptlrpc_service_part *svcpt)
> return !list_empty(&svcpt->scp_req_incoming);
> }
>
> +/* We perfer lifo queuing, but kernel doesn't provide that yet. */
> +#ifndef wait_event_idle_exclusive_lifo
> +#define wait_event_idle_exclusive_lifo wait_event_idle_exclusive
> +#define wait_event_idle_exclusive_lifo_timeout wait_event_idle_exclusive_timeout
> +#endif
> +
> static __attribute__((__noinline__)) int
> ptlrpc_wait_event(struct ptlrpc_service_part *svcpt,
> struct ptlrpc_thread *thread)
> {
> /* Don't exit while there are replies to be handled */
> - struct l_wait_info lwi = LWI_TIMEOUT(svcpt->scp_rqbd_timeout,
> - ptlrpc_retry_rqbds, svcpt);
>
> /* XXX: Add this back when libcfs watchdog is merged upstream
> lc_watchdog_disable(thread->t_watchdog);
> @@ -1982,13 +1977,25 @@ ptlrpc_wait_event(struct ptlrpc_service_part *svcpt,
>
> cond_resched();
>
> - l_wait_event_exclusive_head(svcpt->scp_waitq,
> - ptlrpc_thread_stopping(thread) ||
> - ptlrpc_server_request_incoming(svcpt) ||
> - ptlrpc_server_request_pending(svcpt,
> - false) ||
> - ptlrpc_rqbd_pending(svcpt) ||
> - ptlrpc_at_check(svcpt), &lwi);
> + if (svcpt->scp_rqbd_timeout == 0)
> + wait_event_idle_exclusive_lifo(
> + svcpt->scp_waitq,
> + ptlrpc_thread_stopping(thread) ||
> + ptlrpc_server_request_incoming(svcpt) ||
> + ptlrpc_server_request_pending(svcpt,
> + false) ||
> + ptlrpc_rqbd_pending(svcpt) ||
> + ptlrpc_at_check(svcpt));
> + else if (0 == wait_event_idle_exclusive_lifo_timeout(
> + svcpt->scp_waitq,
> + ptlrpc_thread_stopping(thread) ||
> + ptlrpc_server_request_incoming(svcpt) ||
> + ptlrpc_server_request_pending(svcpt,
> + false) ||
> + ptlrpc_rqbd_pending(svcpt) ||
> + ptlrpc_at_check(svcpt),
> + svcpt->scp_rqbd_timeout))
> + svcpt->scp_rqbd_timeout = 0;
>
> if (ptlrpc_thread_stopping(thread))
> return -EINTR;
>
>
>