| /* |
| * 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 "../../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_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 |
| */ |
| if (count) |
| count = roundup_pow_of_two(count); |
| |
| if (callback != LNET_EQ_HANDLER_NONE && count) |
| 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 && callback == LNET_EQ_HANDLER_NONE) |
| return -EINVAL; |
| |
| eq = lnet_eq_alloc(); |
| if (!eq) |
| return -ENOMEM; |
| |
| if (count) { |
| LIBCFS_ALLOC(eq->eq_events, count * sizeof(lnet_event_t)); |
| if (!eq->eq_events) |
| 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) |
| 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) |
| LIBCFS_FREE(eq->eq_events, count * sizeof(lnet_event_t)); |
| |
| if (eq->eq_refs) |
| 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_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) { |
| rc = -ENOENT; |
| goto out; |
| } |
| |
| cfs_percpt_for_each(ref, i, eq->eq_refs) { |
| LASSERT(*ref >= 0); |
| if (!*ref) |
| 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(eq); |
| out: |
| lnet_eq_wait_unlock(); |
| lnet_res_unlock(LNET_LOCK_EX); |
| |
| if (events) |
| LIBCFS_FREE(events, size * sizeof(lnet_event_t)); |
| if (refs) |
| 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) { |
| 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(); |
| } |
| |
| static 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; |
| |
| /* 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. |
| */ |
| |
| /** |
| * 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. |
| */ |
| |
| static int |
| lnet_eq_wait_locked(int *timeout_ms) |
| __must_hold(&the_lnet.ln_eq_wait_lock) |
| { |
| int tms = *timeout_ms; |
| int wait; |
| wait_queue_t wl; |
| unsigned long now; |
| |
| if (!tms) |
| return -ENXIO; /* don't want to wait and no new event */ |
| |
| init_waitqueue_entry(&wl, current); |
| set_current_state(TASK_INTERRUPTIBLE); |
| add_wait_queue(&the_lnet.ln_eq_waitq, &wl); |
| |
| lnet_eq_wait_unlock(); |
| |
| if (tms < 0) { |
| schedule(); |
| } else { |
| now = jiffies; |
| schedule_timeout(msecs_to_jiffies(tms)); |
| tms -= jiffies_to_msecs(jiffies - now); |
| if (tms < 0) /* no more wait but may have new event */ |
| tms = 0; |
| } |
| |
| wait = tms; /* 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; |
| |
| 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) { |
| lnet_eq_wait_unlock(); |
| return -ENOENT; |
| } |
| |
| rc = lnet_eq_dequeue_event(eq, event); |
| if (rc) { |
| lnet_eq_wait_unlock(); |
| *which = i; |
| return rc; |
| } |
| } |
| |
| if (!wait) |
| 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; |
| } |