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13 * General Public License version 2 for more details (a copy is included
14 * in the LICENSE file that accompanied this code).
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21 * CA 95054 USA or visit www.sun.com if you need additional information or
27 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
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30 * Copyright (c) 2012, Intel Corporation.
33 * This file is part of Lustre, http://www.lustre.org/
34 * Lustre is a trademark of Sun Microsystems, Inc.
38 * Library level Event queue management routines
41 #define DEBUG_SUBSYSTEM S_LNET
42 #include "../../include/linux/lnet/lib-lnet.h"
45 * Create an event queue that has room for \a count number of events.
47 * The event queue is circular and older events will be overwritten by new
48 * ones if they are not removed in time by the user using the functions
49 * LNetEQGet(), LNetEQWait(), or LNetEQPoll(). It is up to the user to
50 * determine the appropriate size of the event queue to prevent this loss
51 * of events. Note that when EQ handler is specified in \a callback, no
52 * event loss can happen, since the handler is run for each event deposited
55 * \param count The number of events to be stored in the event queue. It
56 * will be rounded up to the next power of two.
57 * \param callback A handler function that runs when an event is deposited
58 * into the EQ. The constant value LNET_EQ_HANDLER_NONE can be used to
59 * indicate that no event handler is desired.
60 * \param handle On successful return, this location will hold a handle for
61 * the newly created EQ.
63 * \retval 0 On success.
64 * \retval -EINVAL If an parameter is not valid.
65 * \retval -ENOMEM If memory for the EQ can't be allocated.
67 * \see lnet_eq_handler_t for the discussion on EQ handler semantics.
70 LNetEQAlloc(unsigned int count
, lnet_eq_handler_t callback
,
71 lnet_handle_eq_t
*handle
)
75 LASSERT (the_lnet
.ln_init
);
76 LASSERT (the_lnet
.ln_refcount
> 0);
78 /* We need count to be a power of 2 so that when eq_{enq,deq}_seq
79 * overflow, they don't skip entries, so the queue has the same
80 * apparent capacity at all times */
82 count
= cfs_power2_roundup(count
);
84 if (callback
!= LNET_EQ_HANDLER_NONE
&& count
!= 0) {
85 CWARN("EQ callback is guaranteed to get every event, "
86 "do you still want to set eqcount %d for polling "
87 "event which will have locking overhead? "
88 "Please contact with developer to confirm\n", count
);
91 /* count can be 0 if only need callback, we can eliminate
92 * overhead of enqueue event */
93 if (count
== 0 && callback
== LNET_EQ_HANDLER_NONE
)
101 LIBCFS_ALLOC(eq
->eq_events
, count
* sizeof(lnet_event_t
));
102 if (eq
->eq_events
== NULL
)
104 /* NB allocator has set all event sequence numbers to 0,
105 * so all them should be earlier than eq_deq_seq */
111 eq
->eq_callback
= callback
;
113 eq
->eq_refs
= cfs_percpt_alloc(lnet_cpt_table(),
114 sizeof(*eq
->eq_refs
[0]));
115 if (eq
->eq_refs
== NULL
)
118 /* MUST hold both exclusive lnet_res_lock */
119 lnet_res_lock(LNET_LOCK_EX
);
120 /* NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do
121 * both EQ lookup and poll event with only lnet_eq_wait_lock */
124 lnet_res_lh_initialize(&the_lnet
.ln_eq_container
, &eq
->eq_lh
);
125 list_add(&eq
->eq_list
, &the_lnet
.ln_eq_container
.rec_active
);
127 lnet_eq_wait_unlock();
128 lnet_res_unlock(LNET_LOCK_EX
);
130 lnet_eq2handle(handle
, eq
);
134 if (eq
->eq_events
!= NULL
)
135 LIBCFS_FREE(eq
->eq_events
, count
* sizeof(lnet_event_t
));
137 if (eq
->eq_refs
!= NULL
)
138 cfs_percpt_free(eq
->eq_refs
);
143 EXPORT_SYMBOL(LNetEQAlloc
);
146 * Release the resources associated with an event queue if it's idle;
147 * otherwise do nothing and it's up to the user to try again.
149 * \param eqh A handle for the event queue to be released.
151 * \retval 0 If the EQ is not in use and freed.
152 * \retval -ENOENT If \a eqh does not point to a valid EQ.
153 * \retval -EBUSY If the EQ is still in use by some MDs.
156 LNetEQFree(lnet_handle_eq_t eqh
)
159 lnet_event_t
*events
= NULL
;
166 LASSERT(the_lnet
.ln_init
);
167 LASSERT(the_lnet
.ln_refcount
> 0);
169 lnet_res_lock(LNET_LOCK_EX
);
170 /* NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do
171 * both EQ lookup and poll event with only lnet_eq_wait_lock */
174 eq
= lnet_handle2eq(&eqh
);
180 cfs_percpt_for_each(ref
, i
, eq
->eq_refs
) {
185 CDEBUG(D_NET
, "Event equeue (%d: %d) busy on destroy.\n",
191 /* stash for free after lock dropped */
192 events
= eq
->eq_events
;
196 lnet_res_lh_invalidate(&eq
->eq_lh
);
197 list_del(&eq
->eq_list
);
198 lnet_eq_free_locked(eq
);
200 lnet_eq_wait_unlock();
201 lnet_res_unlock(LNET_LOCK_EX
);
204 LIBCFS_FREE(events
, size
* sizeof(lnet_event_t
));
206 cfs_percpt_free(refs
);
210 EXPORT_SYMBOL(LNetEQFree
);
213 lnet_eq_enqueue_event(lnet_eq_t
*eq
, lnet_event_t
*ev
)
215 /* MUST called with resource lock hold but w/o lnet_eq_wait_lock */
218 if (eq
->eq_size
== 0) {
219 LASSERT(eq
->eq_callback
!= LNET_EQ_HANDLER_NONE
);
225 ev
->sequence
= eq
->eq_enq_seq
++;
227 LASSERT(eq
->eq_size
== LOWEST_BIT_SET(eq
->eq_size
));
228 index
= ev
->sequence
& (eq
->eq_size
- 1);
230 eq
->eq_events
[index
] = *ev
;
232 if (eq
->eq_callback
!= LNET_EQ_HANDLER_NONE
)
235 /* Wake anyone waiting in LNetEQPoll() */
236 if (waitqueue_active(&the_lnet
.ln_eq_waitq
))
237 wake_up_all(&the_lnet
.ln_eq_waitq
);
238 lnet_eq_wait_unlock();
242 lnet_eq_dequeue_event(lnet_eq_t
*eq
, lnet_event_t
*ev
)
244 int new_index
= eq
->eq_deq_seq
& (eq
->eq_size
- 1);
245 lnet_event_t
*new_event
= &eq
->eq_events
[new_index
];
248 /* must called with lnet_eq_wait_lock hold */
249 if (LNET_SEQ_GT(eq
->eq_deq_seq
, new_event
->sequence
))
252 /* We've got a new event... */
255 CDEBUG(D_INFO
, "event: %p, sequence: %lu, eq->size: %u\n",
256 new_event
, eq
->eq_deq_seq
, eq
->eq_size
);
258 /* ...but did it overwrite an event we've not seen yet? */
259 if (eq
->eq_deq_seq
== new_event
->sequence
) {
262 /* don't complain with CERROR: some EQs are sized small
263 * anyway; if it's important, the caller should complain */
264 CDEBUG(D_NET
, "Event Queue Overflow: eq seq %lu ev seq %lu\n",
265 eq
->eq_deq_seq
, new_event
->sequence
);
269 eq
->eq_deq_seq
= new_event
->sequence
+ 1;
274 * A nonblocking function that can be used to get the next event in an EQ.
275 * If an event handler is associated with the EQ, the handler will run before
276 * this function returns successfully. The event is removed from the queue.
278 * \param eventq A handle for the event queue.
279 * \param event On successful return (1 or -EOVERFLOW), this location will
280 * hold the next event in the EQ.
282 * \retval 0 No pending event in the EQ.
283 * \retval 1 Indicates success.
284 * \retval -ENOENT If \a eventq does not point to a valid EQ.
285 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
286 * at least one event between this event and the last event obtained from the
287 * EQ has been dropped due to limited space in the EQ.
290 LNetEQGet (lnet_handle_eq_t eventq
, lnet_event_t
*event
)
294 return LNetEQPoll(&eventq
, 1, 0,
297 EXPORT_SYMBOL(LNetEQGet
);
300 * Block the calling process until there is an event in the EQ.
301 * If an event handler is associated with the EQ, the handler will run before
302 * this function returns successfully. This function returns the next event
303 * in the EQ and removes it from the EQ.
305 * \param eventq A handle for the event queue.
306 * \param event On successful return (1 or -EOVERFLOW), this location will
307 * hold the next event in the EQ.
309 * \retval 1 Indicates success.
310 * \retval -ENOENT If \a eventq does not point to a valid EQ.
311 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
312 * at least one event between this event and the last event obtained from the
313 * EQ has been dropped due to limited space in the EQ.
316 LNetEQWait (lnet_handle_eq_t eventq
, lnet_event_t
*event
)
320 return LNetEQPoll(&eventq
, 1, LNET_TIME_FOREVER
,
323 EXPORT_SYMBOL(LNetEQWait
);
327 lnet_eq_wait_locked(int *timeout_ms
)
328 __must_hold(&the_lnet
.ln_eq_wait_lock
)
330 int tms
= *timeout_ms
;
336 return -1; /* don't want to wait and no new event */
338 init_waitqueue_entry(&wl
, current
);
339 set_current_state(TASK_INTERRUPTIBLE
);
340 add_wait_queue(&the_lnet
.ln_eq_waitq
, &wl
);
342 lnet_eq_wait_unlock();
350 now
= cfs_time_current();
351 schedule_timeout(cfs_time_seconds(tms
) / 1000);
352 cfs_duration_usec(cfs_time_sub(cfs_time_current(), now
), &tv
);
353 tms
-= (int)(tv
.tv_sec
* 1000 + tv
.tv_usec
/ 1000);
354 if (tms
< 0) /* no more wait but may have new event */
358 wait
= tms
!= 0; /* might need to call here again */
362 remove_wait_queue(&the_lnet
.ln_eq_waitq
, &wl
);
370 * Block the calling process until there's an event from a set of EQs or
373 * If an event handler is associated with the EQ, the handler will run before
374 * this function returns successfully, in which case the corresponding event
377 * LNetEQPoll() provides a timeout to allow applications to poll, block for a
378 * fixed period, or block indefinitely.
380 * \param eventqs,neq An array of EQ handles, and size of the array.
381 * \param timeout_ms Time in milliseconds to wait for an event to occur on
382 * one of the EQs. The constant LNET_TIME_FOREVER can be used to indicate an
384 * \param event,which On successful return (1 or -EOVERFLOW), \a event will
385 * hold the next event in the EQs, and \a which will contain the index of the
386 * EQ from which the event was taken.
388 * \retval 0 No pending event in the EQs after timeout.
389 * \retval 1 Indicates success.
390 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
391 * at least one event between this event and the last event obtained from the
392 * EQ indicated by \a which has been dropped due to limited space in the EQ.
393 * \retval -ENOENT If there's an invalid handle in \a eventqs.
396 LNetEQPoll(lnet_handle_eq_t
*eventqs
, int neq
, int timeout_ms
,
397 lnet_event_t
*event
, int *which
)
403 LASSERT (the_lnet
.ln_init
);
404 LASSERT (the_lnet
.ln_refcount
> 0);
412 for (i
= 0; i
< neq
; i
++) {
413 lnet_eq_t
*eq
= lnet_handle2eq(&eventqs
[i
]);
416 lnet_eq_wait_unlock();
420 rc
= lnet_eq_dequeue_event(eq
, event
);
422 lnet_eq_wait_unlock();
432 * return value of lnet_eq_wait_locked:
433 * -1 : did nothing and it's sure no new event
434 * 1 : sleep inside and wait until new event
435 * 0 : don't want to wait anymore, but might have new event
436 * so need to call dequeue again
438 wait
= lnet_eq_wait_locked(&timeout_ms
);
439 if (wait
< 0) /* no new event */
443 lnet_eq_wait_unlock();