staging: lustre: replace l_wait_event_exclusive_head() with wait_event_idle_exclusive

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 arranges 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>
Reviewed-by: Patrick Farrell <paf@cray.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/lustre/lustre/ptlrpc/service.c b/drivers/staging/lustre/lustre/ptlrpc/service.c
index 6e340341743408c86b745f2534478121d08bea8c..29fdb54f16cac51b2db3d4dd2b05f4b728b213e9 100644 (file)
--- 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;