diff options
Diffstat (limited to 'drivers/staging/lustre/lnet/lnet/lib-eq.c')
| -rw-r--r-- | drivers/staging/lustre/lnet/lnet/lib-eq.c | 447 |
1 files changed, 447 insertions, 0 deletions
diff --git a/drivers/staging/lustre/lnet/lnet/lib-eq.c b/drivers/staging/lustre/lnet/lnet/lib-eq.c new file mode 100644 index 000000000000..78297a7d94e8 --- /dev/null +++ b/drivers/staging/lustre/lnet/lnet/lib-eq.c @@ -0,0 +1,447 @@ +/* + * GPL HEADER START + * + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 only, + * as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License version 2 for more details (a copy is included + * in the LICENSE file that accompanied this code). + * + * You should have received a copy of the GNU General Public License + * version 2 along with this program; If not, see + * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf + * + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + * + * GPL HEADER END + */ +/* + * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved. + * Use is subject to license terms. + * + * Copyright (c) 2012, Intel Corporation. + */ +/* + * This file is part of Lustre, http://www.lustre.org/ + * Lustre is a trademark of Sun Microsystems, Inc. + * + * lnet/lnet/lib-eq.c + * + * Library level Event queue management routines + */ + +#define DEBUG_SUBSYSTEM S_LNET +#include <linux/lnet/lib-lnet.h> + +/** + * Create an event queue that has room for \a count number of events. + * + * The event queue is circular and older events will be overwritten by new + * ones if they are not removed in time by the user using the functions + * LNetEQGet(), LNetEQWait(), or LNetEQPoll(). It is up to the user to + * determine the appropriate size of the event queue to prevent this loss + * of events. Note that when EQ handler is specified in \a callback, no + * event loss can happen, since the handler is run for each event deposited + * into the EQ. + * + * \param count The number of events to be stored in the event queue. It + * will be rounded up to the next power of two. + * \param callback A handler function that runs when an event is deposited + * into the EQ. The constant value LNET_EQ_HANDLER_NONE can be used to + * indicate that no event handler is desired. + * \param handle On successful return, this location will hold a handle for + * the newly created EQ. + * + * \retval 0 On success. + * \retval -EINVAL If an parameter is not valid. + * \retval -ENOMEM If memory for the EQ can't be allocated. + * + * \see lnet_eq_handler_t for the discussion on EQ handler semantics. + */ +int +LNetEQAlloc(unsigned int count, lnet_eq_handler_t callback, + lnet_handle_eq_t *handle) +{ + lnet_eq_t *eq; + + LASSERT (the_lnet.ln_init); + LASSERT (the_lnet.ln_refcount > 0); + + /* We need count to be a power of 2 so that when eq_{enq,deq}_seq + * overflow, they don't skip entries, so the queue has the same + * apparent capacity at all times */ + + count = cfs_power2_roundup(count); + + if (callback != LNET_EQ_HANDLER_NONE && count != 0) { + CWARN("EQ callback is guaranteed to get every event, " + "do you still want to set eqcount %d for polling " + "event which will have locking overhead? " + "Please contact with developer to confirm\n", count); + } + + /* count can be 0 if only need callback, we can eliminate + * overhead of enqueue event */ + if (count == 0 && callback == LNET_EQ_HANDLER_NONE) + return -EINVAL; + + eq = lnet_eq_alloc(); + if (eq == NULL) + return -ENOMEM; + + if (count != 0) { + LIBCFS_ALLOC(eq->eq_events, count * sizeof(lnet_event_t)); + if (eq->eq_events == NULL) + goto failed; + /* NB allocator has set all event sequence numbers to 0, + * so all them should be earlier than eq_deq_seq */ + } + + eq->eq_deq_seq = 1; + eq->eq_enq_seq = 1; + eq->eq_size = count; + eq->eq_callback = callback; + + eq->eq_refs = cfs_percpt_alloc(lnet_cpt_table(), + sizeof(*eq->eq_refs[0])); + if (eq->eq_refs == NULL) + goto failed; + + /* MUST hold both exclusive lnet_res_lock */ + lnet_res_lock(LNET_LOCK_EX); + /* NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do + * both EQ lookup and poll event with only lnet_eq_wait_lock */ + lnet_eq_wait_lock(); + + lnet_res_lh_initialize(&the_lnet.ln_eq_container, &eq->eq_lh); + list_add(&eq->eq_list, &the_lnet.ln_eq_container.rec_active); + + lnet_eq_wait_unlock(); + lnet_res_unlock(LNET_LOCK_EX); + + lnet_eq2handle(handle, eq); + return 0; + +failed: + if (eq->eq_events != NULL) + LIBCFS_FREE(eq->eq_events, count * sizeof(lnet_event_t)); + + if (eq->eq_refs != NULL) + cfs_percpt_free(eq->eq_refs); + + lnet_eq_free(eq); + return -ENOMEM; +} +EXPORT_SYMBOL(LNetEQAlloc); + +/** + * Release the resources associated with an event queue if it's idle; + * otherwise do nothing and it's up to the user to try again. + * + * \param eqh A handle for the event queue to be released. + * + * \retval 0 If the EQ is not in use and freed. + * \retval -ENOENT If \a eqh does not point to a valid EQ. + * \retval -EBUSY If the EQ is still in use by some MDs. + */ +int +LNetEQFree(lnet_handle_eq_t eqh) +{ + struct lnet_eq *eq; + lnet_event_t *events = NULL; + int **refs = NULL; + int *ref; + int rc = 0; + int size = 0; + int i; + + LASSERT(the_lnet.ln_init); + LASSERT(the_lnet.ln_refcount > 0); + + lnet_res_lock(LNET_LOCK_EX); + /* NB: hold lnet_eq_wait_lock for EQ link/unlink, so we can do + * both EQ lookup and poll event with only lnet_eq_wait_lock */ + lnet_eq_wait_lock(); + + eq = lnet_handle2eq(&eqh); + if (eq == NULL) { + rc = -ENOENT; + goto out; + } + + cfs_percpt_for_each(ref, i, eq->eq_refs) { + LASSERT(*ref >= 0); + if (*ref == 0) + continue; + + CDEBUG(D_NET, "Event equeue (%d: %d) busy on destroy.\n", + i, *ref); + rc = -EBUSY; + goto out; + } + + /* stash for free after lock dropped */ + events = eq->eq_events; + size = eq->eq_size; + refs = eq->eq_refs; + + lnet_res_lh_invalidate(&eq->eq_lh); + list_del(&eq->eq_list); + lnet_eq_free_locked(eq); + out: + lnet_eq_wait_unlock(); + lnet_res_unlock(LNET_LOCK_EX); + + if (events != NULL) + LIBCFS_FREE(events, size * sizeof(lnet_event_t)); + if (refs != NULL) + cfs_percpt_free(refs); + + return rc; +} +EXPORT_SYMBOL(LNetEQFree); + +void +lnet_eq_enqueue_event(lnet_eq_t *eq, lnet_event_t *ev) +{ + /* MUST called with resource lock hold but w/o lnet_eq_wait_lock */ + int index; + + if (eq->eq_size == 0) { + LASSERT(eq->eq_callback != LNET_EQ_HANDLER_NONE); + eq->eq_callback(ev); + return; + } + + lnet_eq_wait_lock(); + ev->sequence = eq->eq_enq_seq++; + + LASSERT(eq->eq_size == LOWEST_BIT_SET(eq->eq_size)); + index = ev->sequence & (eq->eq_size - 1); + + eq->eq_events[index] = *ev; + + if (eq->eq_callback != LNET_EQ_HANDLER_NONE) + eq->eq_callback(ev); + + /* Wake anyone waiting in LNetEQPoll() */ + if (waitqueue_active(&the_lnet.ln_eq_waitq)) + wake_up_all(&the_lnet.ln_eq_waitq); + lnet_eq_wait_unlock(); +} + +int +lnet_eq_dequeue_event(lnet_eq_t *eq, lnet_event_t *ev) +{ + int new_index = eq->eq_deq_seq & (eq->eq_size - 1); + lnet_event_t *new_event = &eq->eq_events[new_index]; + int rc; + ENTRY; + + /* must called with lnet_eq_wait_lock hold */ + if (LNET_SEQ_GT(eq->eq_deq_seq, new_event->sequence)) + RETURN(0); + + /* We've got a new event... */ + *ev = *new_event; + + CDEBUG(D_INFO, "event: %p, sequence: %lu, eq->size: %u\n", + new_event, eq->eq_deq_seq, eq->eq_size); + + /* ...but did it overwrite an event we've not seen yet? */ + if (eq->eq_deq_seq == new_event->sequence) { + rc = 1; + } else { + /* don't complain with CERROR: some EQs are sized small + * anyway; if it's important, the caller should complain */ + CDEBUG(D_NET, "Event Queue Overflow: eq seq %lu ev seq %lu\n", + eq->eq_deq_seq, new_event->sequence); + rc = -EOVERFLOW; + } + + eq->eq_deq_seq = new_event->sequence + 1; + RETURN(rc); +} + +/** + * A nonblocking function that can be used to get the next event in an EQ. + * If an event handler is associated with the EQ, the handler will run before + * this function returns successfully. The event is removed from the queue. + * + * \param eventq A handle for the event queue. + * \param event On successful return (1 or -EOVERFLOW), this location will + * hold the next event in the EQ. + * + * \retval 0 No pending event in the EQ. + * \retval 1 Indicates success. + * \retval -ENOENT If \a eventq does not point to a valid EQ. + * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that + * at least one event between this event and the last event obtained from the + * EQ has been dropped due to limited space in the EQ. + */ +int +LNetEQGet (lnet_handle_eq_t eventq, lnet_event_t *event) +{ + int which; + + return LNetEQPoll(&eventq, 1, 0, + event, &which); +} +EXPORT_SYMBOL(LNetEQGet); + +/** + * Block the calling process until there is an event in the EQ. + * If an event handler is associated with the EQ, the handler will run before + * this function returns successfully. This function returns the next event + * in the EQ and removes it from the EQ. + * + * \param eventq A handle for the event queue. + * \param event On successful return (1 or -EOVERFLOW), this location will + * hold the next event in the EQ. + * + * \retval 1 Indicates success. + * \retval -ENOENT If \a eventq does not point to a valid EQ. + * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that + * at least one event between this event and the last event obtained from the + * EQ has been dropped due to limited space in the EQ. + */ +int +LNetEQWait (lnet_handle_eq_t eventq, lnet_event_t *event) +{ + int which; + + return LNetEQPoll(&eventq, 1, LNET_TIME_FOREVER, + event, &which); +} +EXPORT_SYMBOL(LNetEQWait); + + +static int +lnet_eq_wait_locked(int *timeout_ms) +{ + int tms = *timeout_ms; + int wait; + wait_queue_t wl; + cfs_time_t now; + + if (tms == 0) + return -1; /* don't want to wait and no new event */ + + init_waitqueue_entry_current(&wl); + set_current_state(TASK_INTERRUPTIBLE); + add_wait_queue(&the_lnet.ln_eq_waitq, &wl); + + lnet_eq_wait_unlock(); + + if (tms < 0) { + waitq_wait(&wl, TASK_INTERRUPTIBLE); + + } else { + struct timeval tv; + + now = cfs_time_current(); + waitq_timedwait(&wl, TASK_INTERRUPTIBLE, + cfs_time_seconds(tms) / 1000); + cfs_duration_usec(cfs_time_sub(cfs_time_current(), now), &tv); + tms -= (int)(tv.tv_sec * 1000 + tv.tv_usec / 1000); + if (tms < 0) /* no more wait but may have new event */ + tms = 0; + } + + wait = tms != 0; /* might need to call here again */ + *timeout_ms = tms; + + lnet_eq_wait_lock(); + remove_wait_queue(&the_lnet.ln_eq_waitq, &wl); + + return wait; +} + + + +/** + * Block the calling process until there's an event from a set of EQs or + * timeout happens. + * + * If an event handler is associated with the EQ, the handler will run before + * this function returns successfully, in which case the corresponding event + * is consumed. + * + * LNetEQPoll() provides a timeout to allow applications to poll, block for a + * fixed period, or block indefinitely. + * + * \param eventqs,neq An array of EQ handles, and size of the array. + * \param timeout_ms Time in milliseconds to wait for an event to occur on + * one of the EQs. The constant LNET_TIME_FOREVER can be used to indicate an + * infinite timeout. + * \param event,which On successful return (1 or -EOVERFLOW), \a event will + * hold the next event in the EQs, and \a which will contain the index of the + * EQ from which the event was taken. + * + * \retval 0 No pending event in the EQs after timeout. + * \retval 1 Indicates success. + * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that + * at least one event between this event and the last event obtained from the + * EQ indicated by \a which has been dropped due to limited space in the EQ. + * \retval -ENOENT If there's an invalid handle in \a eventqs. + */ +int +LNetEQPoll(lnet_handle_eq_t *eventqs, int neq, int timeout_ms, + lnet_event_t *event, int *which) +{ + int wait = 1; + int rc; + int i; + ENTRY; + + LASSERT (the_lnet.ln_init); + LASSERT (the_lnet.ln_refcount > 0); + + if (neq < 1) + RETURN(-ENOENT); + + lnet_eq_wait_lock(); + + for (;;) { + for (i = 0; i < neq; i++) { + lnet_eq_t *eq = lnet_handle2eq(&eventqs[i]); + + if (eq == NULL) { + lnet_eq_wait_unlock(); + RETURN(-ENOENT); + } + + rc = lnet_eq_dequeue_event(eq, event); + if (rc != 0) { + lnet_eq_wait_unlock(); + *which = i; + RETURN(rc); + } + } + + if (wait == 0) + break; + + /* + * return value of lnet_eq_wait_locked: + * -1 : did nothing and it's sure no new event + * 1 : sleep inside and wait until new event + * 0 : don't want to wait anymore, but might have new event + * so need to call dequeue again + */ + wait = lnet_eq_wait_locked(&timeout_ms); + if (wait < 0) /* no new event */ + break; + } + + lnet_eq_wait_unlock(); + RETURN(0); +} |