/*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2002, Jeffrey Roberson <jeff@freebsd.org> * Copyright (c) 2008-2009, Lawrence Stewart <lstewart@freebsd.org> * Copyright (c) 2009-2010, The FreeBSD Foundation * All rights reserved. * * Portions of this software were developed at the Centre for Advanced * Internet Architectures, Swinburne University of Technology, Melbourne, * Australia by Lawrence Stewart under sponsorship from the FreeBSD Foundation. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice unmodified, this list of conditions, and the following * disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include <sys/cdefs.h> __FBSDID("$FreeBSD$"); #include "opt_mac.h" #include <sys/param.h> #include <sys/systm.h> #include <sys/kernel.h> #include <sys/kthread.h> #include <sys/lock.h> #include <sys/mount.h> #include <sys/mutex.h> #include <sys/namei.h> #include <sys/proc.h> #include <sys/vnode.h> #include <sys/alq.h> #include <sys/malloc.h> #include <sys/unistd.h> #include <sys/fcntl.h> #include <sys/eventhandler.h> #include <security/mac/mac_framework.h> /* Async. Logging Queue */ struct alq { char *aq_entbuf; /* Buffer for stored entries */ int aq_entmax; /* Max entries */ int aq_entlen; /* Entry length */ int aq_freebytes; /* Bytes available in buffer */ int aq_buflen; /* Total length of our buffer */ int aq_writehead; /* Location for next write */ int aq_writetail; /* Flush starts at this location */ int aq_wrapearly; /* # bytes left blank at end of buf */ int aq_flags; /* Queue flags */ int aq_waiters; /* Num threads waiting for resources * NB: Used as a wait channel so must * not be first field in the alq struct */ struct ale aq_getpost; /* ALE for use by get/post */ struct mtx aq_mtx; /* Queue lock */ struct vnode *aq_vp; /* Open vnode handle */ struct ucred *aq_cred; /* Credentials of the opening thread */ LIST_ENTRY(alq) aq_act; /* List of active queues */ LIST_ENTRY(alq) aq_link; /* List of all queues */ }; #define AQ_WANTED 0x0001 /* Wakeup sleeper when io is done */ #define AQ_ACTIVE 0x0002 /* on the active list */ #define AQ_FLUSHING 0x0004 /* doing IO */ #define AQ_SHUTDOWN 0x0008 /* Queue no longer valid */ #define AQ_ORDERED 0x0010 /* Queue enforces ordered writes */ #define AQ_LEGACY 0x0020 /* Legacy queue (fixed length writes) */ #define ALQ_LOCK(alq) mtx_lock_spin(&(alq)->aq_mtx) #define ALQ_UNLOCK(alq) mtx_unlock_spin(&(alq)->aq_mtx) #define HAS_PENDING_DATA(alq) ((alq)->aq_freebytes != (alq)->aq_buflen) static MALLOC_DEFINE(M_ALD, "ALD", "ALD"); /* * The ald_mtx protects the ald_queues list and the ald_active list. */ static struct mtx ald_mtx; static LIST_HEAD(, alq) ald_queues; static LIST_HEAD(, alq) ald_active; static int ald_shutingdown = 0; struct thread *ald_thread; static struct proc *ald_proc; static eventhandler_tag alq_eventhandler_tag = NULL; #define ALD_LOCK() mtx_lock(&ald_mtx) #define ALD_UNLOCK() mtx_unlock(&ald_mtx) /* Daemon functions */ static int ald_add(struct alq *); static int ald_rem(struct alq *); static void ald_startup(void *); static void ald_daemon(void); static void ald_shutdown(void *, int); static void ald_activate(struct alq *); static void ald_deactivate(struct alq *); /* Internal queue functions */ static void alq_shutdown(struct alq *); static void alq_destroy(struct alq *); static int alq_doio(struct alq *); /* * Add a new queue to the global list. Fail if we're shutting down. */ static int ald_add(struct alq *alq) { int error; error = 0; ALD_LOCK(); if (ald_shutingdown) { error = EBUSY; goto done; } LIST_INSERT_HEAD(&ald_queues, alq, aq_link); done: ALD_UNLOCK(); return (error); } /* * Remove a queue from the global list unless we're shutting down. If so, * the ald will take care of cleaning up it's resources. */ static int ald_rem(struct alq *alq) { int error; error = 0; ALD_LOCK(); if (ald_shutingdown) { error = EBUSY; goto done; } LIST_REMOVE(alq, aq_link); done: ALD_UNLOCK(); return (error); } /* * Put a queue on the active list. This will schedule it for writing. */ static void ald_activate(struct alq *alq) { LIST_INSERT_HEAD(&ald_active, alq, aq_act); wakeup(&ald_active); } static void ald_deactivate(struct alq *alq) { LIST_REMOVE(alq, aq_act); alq->aq_flags &= ~AQ_ACTIVE; } static void ald_startup(void *unused) { mtx_init(&ald_mtx, "ALDmtx", NULL, MTX_DEF|MTX_QUIET); LIST_INIT(&ald_queues); LIST_INIT(&ald_active); } static void ald_daemon(void) { int needwakeup; struct alq *alq; ald_thread = FIRST_THREAD_IN_PROC(ald_proc); alq_eventhandler_tag = EVENTHANDLER_REGISTER(shutdown_pre_sync, ald_shutdown, NULL, SHUTDOWN_PRI_FIRST); ALD_LOCK(); for (;;) { while ((alq = LIST_FIRST(&ald_active)) == NULL && !ald_shutingdown) mtx_sleep(&ald_active, &ald_mtx, PWAIT, "aldslp", 0); /* Don't shutdown until all active ALQs are flushed. */ if (ald_shutingdown && alq == NULL) { ALD_UNLOCK(); break; } ALQ_LOCK(alq); ald_deactivate(alq); ALD_UNLOCK(); needwakeup = alq_doio(alq); ALQ_UNLOCK(alq); if (needwakeup) wakeup_one(alq); ALD_LOCK(); } kproc_exit(0); } static void ald_shutdown(void *arg, int howto) { struct alq *alq; ALD_LOCK(); /* Ensure no new queues can be created. */ ald_shutingdown = 1; /* Shutdown all ALQs prior to terminating the ald_daemon. */ while ((alq = LIST_FIRST(&ald_queues)) != NULL) { LIST_REMOVE(alq, aq_link); ALD_UNLOCK(); alq_shutdown(alq); ALD_LOCK(); } /* At this point, all ALQs are flushed and shutdown. */ /* * Wake ald_daemon so that it exits. It won't be able to do * anything until we mtx_sleep because we hold the ald_mtx. */ wakeup(&ald_active); /* Wait for ald_daemon to exit. */ mtx_sleep(ald_proc, &ald_mtx, PWAIT, "aldslp", 0); ALD_UNLOCK(); } static void alq_shutdown(struct alq *alq) { ALQ_LOCK(alq); /* Stop any new writers. */ alq->aq_flags |= AQ_SHUTDOWN; /* * If the ALQ isn't active but has unwritten data (possible if * the ALQ_NOACTIVATE flag has been used), explicitly activate the * ALQ here so that the pending data gets flushed by the ald_daemon. */ if (!(alq->aq_flags & AQ_ACTIVE) && HAS_PENDING_DATA(alq)) { alq->aq_flags |= AQ_ACTIVE; ALQ_UNLOCK(alq); ALD_LOCK(); ald_activate(alq); ALD_UNLOCK(); ALQ_LOCK(alq); } /* Drain IO */ while (alq->aq_flags & AQ_ACTIVE) { alq->aq_flags |= AQ_WANTED; msleep_spin(alq, &alq->aq_mtx, "aldclose", 0); } ALQ_UNLOCK(alq); vn_close(alq->aq_vp, FWRITE, alq->aq_cred, curthread); crfree(alq->aq_cred); } void alq_destroy(struct alq *alq) { /* Drain all pending IO. */ alq_shutdown(alq); mtx_destroy(&alq->aq_mtx); free(alq->aq_entbuf, M_ALD); free(alq, M_ALD); } /* * Flush all pending data to disk. This operation will block. */ static int alq_doio(struct alq *alq) { struct thread *td; struct mount *mp; struct vnode *vp; struct uio auio; struct iovec aiov[2]; int totlen; int iov; int wrapearly; KASSERT((HAS_PENDING_DATA(alq)), ("%s: queue empty!", __func__)); vp = alq->aq_vp; td = curthread; totlen = 0; iov = 1; wrapearly = alq->aq_wrapearly; bzero(&aiov, sizeof(aiov)); bzero(&auio, sizeof(auio)); /* Start the write from the location of our buffer tail pointer. */ aiov[0].iov_base = alq->aq_entbuf + alq->aq_writetail; if (alq->aq_writetail < alq->aq_writehead) { /* Buffer not wrapped. */ totlen = aiov[0].iov_len = alq->aq_writehead - alq->aq_writetail; } else if (alq->aq_writehead == 0) { /* Buffer not wrapped (special case to avoid an empty iov). */ totlen = aiov[0].iov_len = alq->aq_buflen - alq->aq_writetail - wrapearly; } else { /* * Buffer wrapped, requires 2 aiov entries: * - first is from writetail to end of buffer * - second is from start of buffer to writehead */ aiov[0].iov_len = alq->aq_buflen - alq->aq_writetail - wrapearly; iov++; aiov[1].iov_base = alq->aq_entbuf; aiov[1].iov_len = alq->aq_writehead; totlen = aiov[0].iov_len + aiov[1].iov_len; } alq->aq_flags |= AQ_FLUSHING; ALQ_UNLOCK(alq); auio.uio_iov = &aiov[0]; auio.uio_offset = 0; auio.uio_segflg = UIO_SYSSPACE; auio.uio_rw = UIO_WRITE; auio.uio_iovcnt = iov; auio.uio_resid = totlen; auio.uio_td = td; /* * Do all of the junk required to write now. */ vn_start_write(vp, &mp, V_WAIT); vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); /* * XXX: VOP_WRITE error checks are ignored. */ #ifdef MAC if (mac_vnode_check_write(alq->aq_cred, NOCRED, vp) == 0) #endif VOP_WRITE(vp, &auio, IO_UNIT | IO_APPEND, alq->aq_cred); VOP_UNLOCK(vp, 0); vn_finished_write(mp); ALQ_LOCK(alq); alq->aq_flags &= ~AQ_FLUSHING; /* Adjust writetail as required, taking into account wrapping. */ alq->aq_writetail = (alq->aq_writetail + totlen + wrapearly) % alq->aq_buflen; alq->aq_freebytes += totlen + wrapearly; /* * If we just flushed part of the buffer which wrapped, reset the * wrapearly indicator. */ if (wrapearly) alq->aq_wrapearly = 0; /* * If we just flushed the buffer completely, reset indexes to 0 to * minimise buffer wraps. * This is also required to ensure alq_getn() can't wedge itself. */ if (!HAS_PENDING_DATA(alq)) alq->aq_writehead = alq->aq_writetail = 0; KASSERT((alq->aq_writetail >= 0 && alq->aq_writetail < alq->aq_buflen), ("%s: aq_writetail < 0 || aq_writetail >= aq_buflen", __func__)); if (alq->aq_flags & AQ_WANTED) { alq->aq_flags &= ~AQ_WANTED; return (1); } return(0); } static struct kproc_desc ald_kp = { "ALQ Daemon", ald_daemon, &ald_proc }; SYSINIT(aldthread, SI_SUB_KTHREAD_IDLE, SI_ORDER_ANY, kproc_start, &ald_kp); SYSINIT(ald, SI_SUB_LOCK, SI_ORDER_ANY, ald_startup, NULL); /* User visible queue functions */ /* * Create the queue data structure, allocate the buffer, and open the file. */ int alq_open_flags(struct alq **alqp, const char *file, struct ucred *cred, int cmode, int size, int flags) { struct thread *td; struct nameidata nd; struct alq *alq; int oflags; int error; KASSERT((size > 0), ("%s: size <= 0", __func__)); *alqp = NULL; td = curthread; NDINIT(&nd, LOOKUP, NOFOLLOW, UIO_SYSSPACE, file, td); oflags = FWRITE | O_NOFOLLOW | O_CREAT; error = vn_open_cred(&nd, &oflags, cmode, 0, cred, NULL); if (error) return (error); NDFREE(&nd, NDF_ONLY_PNBUF); /* We just unlock so we hold a reference */ VOP_UNLOCK(nd.ni_vp, 0); alq = malloc(sizeof(*alq), M_ALD, M_WAITOK|M_ZERO); alq->aq_vp = nd.ni_vp; alq->aq_cred = crhold(cred); mtx_init(&alq->aq_mtx, "ALD Queue", NULL, MTX_SPIN|MTX_QUIET); alq->aq_buflen = size; alq->aq_entmax = 0; alq->aq_entlen = 0; alq->aq_freebytes = alq->aq_buflen; alq->aq_entbuf = malloc(alq->aq_buflen, M_ALD, M_WAITOK|M_ZERO); alq->aq_writehead = alq->aq_writetail = 0; if (flags & ALQ_ORDERED) alq->aq_flags |= AQ_ORDERED; if ((error = ald_add(alq)) != 0) { alq_destroy(alq); return (error); } *alqp = alq; return (0); } int alq_open(struct alq **alqp, const char *file, struct ucred *cred, int cmode, int size, int count) { int ret; KASSERT((count >= 0), ("%s: count < 0", __func__)); if (count > 0) { if ((ret = alq_open_flags(alqp, file, cred, cmode, size*count, 0)) == 0) { (*alqp)->aq_flags |= AQ_LEGACY; (*alqp)->aq_entmax = count; (*alqp)->aq_entlen = size; } } else ret = alq_open_flags(alqp, file, cred, cmode, size, 0); return (ret); } /* * Copy a new entry into the queue. If the operation would block either * wait or return an error depending on the value of waitok. */ int alq_writen(struct alq *alq, void *data, int len, int flags) { int activate, copy, ret; void *waitchan; KASSERT((len > 0 && len <= alq->aq_buflen), ("%s: len <= 0 || len > aq_buflen", __func__)); activate = ret = 0; copy = len; waitchan = NULL; ALQ_LOCK(alq); /* * Fail to perform the write and return EWOULDBLOCK if: * - The message is larger than our underlying buffer. * - The ALQ is being shutdown. * - There is insufficient free space in our underlying buffer * to accept the message and the user can't wait for space. * - There is insufficient free space in our underlying buffer * to accept the message and the alq is inactive due to prior * use of the ALQ_NOACTIVATE flag (which would lead to deadlock). */ if (len > alq->aq_buflen || alq->aq_flags & AQ_SHUTDOWN || (((flags & ALQ_NOWAIT) || (!(alq->aq_flags & AQ_ACTIVE) && HAS_PENDING_DATA(alq))) && alq->aq_freebytes < len)) { ALQ_UNLOCK(alq); return (EWOULDBLOCK); } /* * If we want ordered writes and there is already at least one thread * waiting for resources to become available, sleep until we're woken. */ if (alq->aq_flags & AQ_ORDERED && alq->aq_waiters > 0) { KASSERT(!(flags & ALQ_NOWAIT), ("%s: ALQ_NOWAIT set but incorrectly ignored!", __func__)); alq->aq_waiters++; msleep_spin(&alq->aq_waiters, &alq->aq_mtx, "alqwnord", 0); alq->aq_waiters--; } /* * (ALQ_WAITOK && aq_freebytes < len) or aq_freebytes >= len, either * enter while loop and sleep until we have enough free bytes (former) * or skip (latter). If AQ_ORDERED is set, only 1 thread at a time will * be in this loop. Otherwise, multiple threads may be sleeping here * competing for ALQ resources. */ while (alq->aq_freebytes < len && !(alq->aq_flags & AQ_SHUTDOWN)) { KASSERT(!(flags & ALQ_NOWAIT), ("%s: ALQ_NOWAIT set but incorrectly ignored!", __func__)); alq->aq_flags |= AQ_WANTED; alq->aq_waiters++; if (waitchan) wakeup(waitchan); msleep_spin(alq, &alq->aq_mtx, "alqwnres", 0); alq->aq_waiters--; /* * If we're the first thread to wake after an AQ_WANTED wakeup * but there isn't enough free space for us, we're going to loop * and sleep again. If there are other threads waiting in this * loop, schedule a wakeup so that they can see if the space * they require is available. */ if (alq->aq_waiters > 0 && !(alq->aq_flags & AQ_ORDERED) && alq->aq_freebytes < len && !(alq->aq_flags & AQ_WANTED)) waitchan = alq; else waitchan = NULL; } /* * If there are waiters, we need to signal the waiting threads after we * complete our work. The alq ptr is used as a wait channel for threads * requiring resources to be freed up. In the AQ_ORDERED case, threads * are not allowed to concurrently compete for resources in the above * while loop, so we use a different wait channel in this case. */ if (alq->aq_waiters > 0) { if (alq->aq_flags & AQ_ORDERED) waitchan = &alq->aq_waiters; else waitchan = alq; } else waitchan = NULL; /* Bail if we're shutting down. */ if (alq->aq_flags & AQ_SHUTDOWN) { ret = EWOULDBLOCK; goto unlock; } /* * If we need to wrap the buffer to accommodate the write, * we'll need 2 calls to bcopy. */ if ((alq->aq_buflen - alq->aq_writehead) < len) copy = alq->aq_buflen - alq->aq_writehead; /* Copy message (or part thereof if wrap required) to the buffer. */ bcopy(data, alq->aq_entbuf + alq->aq_writehead, copy); alq->aq_writehead += copy; if (alq->aq_writehead >= alq->aq_buflen) { KASSERT((alq->aq_writehead == alq->aq_buflen), ("%s: alq->aq_writehead (%d) > alq->aq_buflen (%d)", __func__, alq->aq_writehead, alq->aq_buflen)); alq->aq_writehead = 0; } if (copy != len) { /* * Wrap the buffer by copying the remainder of our message * to the start of the buffer and resetting aq_writehead. */ bcopy(((uint8_t *)data)+copy, alq->aq_entbuf, len - copy); alq->aq_writehead = len - copy; } KASSERT((alq->aq_writehead >= 0 && alq->aq_writehead < alq->aq_buflen), ("%s: aq_writehead < 0 || aq_writehead >= aq_buflen", __func__)); alq->aq_freebytes -= len; if (!(alq->aq_flags & AQ_ACTIVE) && !(flags & ALQ_NOACTIVATE)) { alq->aq_flags |= AQ_ACTIVE; activate = 1; } KASSERT((HAS_PENDING_DATA(alq)), ("%s: queue empty!", __func__)); unlock: ALQ_UNLOCK(alq); if (activate) { ALD_LOCK(); ald_activate(alq); ALD_UNLOCK(); } /* NB: We rely on wakeup_one waking threads in a FIFO manner. */ if (waitchan != NULL) wakeup_one(waitchan); return (ret); } int alq_write(struct alq *alq, void *data, int flags) { /* Should only be called in fixed length message (legacy) mode. */ KASSERT((alq->aq_flags & AQ_LEGACY), ("%s: fixed length write on variable length queue", __func__)); return (alq_writen(alq, data, alq->aq_entlen, flags)); } /* * Retrieve a pointer for the ALQ to write directly into, avoiding bcopy. */ struct ale * alq_getn(struct alq *alq, int len, int flags) { int contigbytes; void *waitchan; KASSERT((len > 0 && len <= alq->aq_buflen), ("%s: len <= 0 || len > alq->aq_buflen", __func__)); waitchan = NULL; ALQ_LOCK(alq); /* * Determine the number of free contiguous bytes. * We ensure elsewhere that if aq_writehead == aq_writetail because * the buffer is empty, they will both be set to 0 and therefore * aq_freebytes == aq_buflen and is fully contiguous. * If they are equal and the buffer is not empty, aq_freebytes will * be 0 indicating the buffer is full. */ if (alq->aq_writehead <= alq->aq_writetail) contigbytes = alq->aq_freebytes; else { contigbytes = alq->aq_buflen - alq->aq_writehead; if (contigbytes < len) { /* * Insufficient space at end of buffer to handle a * contiguous write. Wrap early if there's space at * the beginning. This will leave a hole at the end * of the buffer which we will have to skip over when * flushing the buffer to disk. */ if (alq->aq_writetail >= len || flags & ALQ_WAITOK) { /* Keep track of # bytes left blank. */ alq->aq_wrapearly = contigbytes; /* Do the wrap and adjust counters. */ contigbytes = alq->aq_freebytes = alq->aq_writetail; alq->aq_writehead = 0; } } } /* * Return a NULL ALE if: * - The message is larger than our underlying buffer. * - The ALQ is being shutdown. * - There is insufficient free space in our underlying buffer * to accept the message and the user can't wait for space. * - There is insufficient free space in our underlying buffer * to accept the message and the alq is inactive due to prior * use of the ALQ_NOACTIVATE flag (which would lead to deadlock). */ if (len > alq->aq_buflen || alq->aq_flags & AQ_SHUTDOWN || (((flags & ALQ_NOWAIT) || (!(alq->aq_flags & AQ_ACTIVE) && HAS_PENDING_DATA(alq))) && contigbytes < len)) { ALQ_UNLOCK(alq); return (NULL); } /* * If we want ordered writes and there is already at least one thread * waiting for resources to become available, sleep until we're woken. */ if (alq->aq_flags & AQ_ORDERED && alq->aq_waiters > 0) { KASSERT(!(flags & ALQ_NOWAIT), ("%s: ALQ_NOWAIT set but incorrectly ignored!", __func__)); alq->aq_waiters++; msleep_spin(&alq->aq_waiters, &alq->aq_mtx, "alqgnord", 0); alq->aq_waiters--; } /* * (ALQ_WAITOK && contigbytes < len) or contigbytes >= len, either enter * while loop and sleep until we have enough contiguous free bytes * (former) or skip (latter). If AQ_ORDERED is set, only 1 thread at a * time will be in this loop. Otherwise, multiple threads may be * sleeping here competing for ALQ resources. */ while (contigbytes < len && !(alq->aq_flags & AQ_SHUTDOWN)) { KASSERT(!(flags & ALQ_NOWAIT), ("%s: ALQ_NOWAIT set but incorrectly ignored!", __func__)); alq->aq_flags |= AQ_WANTED; alq->aq_waiters++; if (waitchan) wakeup(waitchan); msleep_spin(alq, &alq->aq_mtx, "alqgnres", 0); alq->aq_waiters--; if (alq->aq_writehead <= alq->aq_writetail) contigbytes = alq->aq_freebytes; else contigbytes = alq->aq_buflen - alq->aq_writehead; /* * If we're the first thread to wake after an AQ_WANTED wakeup * but there isn't enough free space for us, we're going to loop * and sleep again. If there are other threads waiting in this * loop, schedule a wakeup so that they can see if the space * they require is available. */ if (alq->aq_waiters > 0 && !(alq->aq_flags & AQ_ORDERED) && contigbytes < len && !(alq->aq_flags & AQ_WANTED)) waitchan = alq; else waitchan = NULL; } /* * If there are waiters, we need to signal the waiting threads after we * complete our work. The alq ptr is used as a wait channel for threads * requiring resources to be freed up. In the AQ_ORDERED case, threads * are not allowed to concurrently compete for resources in the above * while loop, so we use a different wait channel in this case. */ if (alq->aq_waiters > 0) { if (alq->aq_flags & AQ_ORDERED) waitchan = &alq->aq_waiters; else waitchan = alq; } else waitchan = NULL; /* Bail if we're shutting down. */ if (alq->aq_flags & AQ_SHUTDOWN) { ALQ_UNLOCK(alq); if (waitchan != NULL) wakeup_one(waitchan); return (NULL); } /* * If we are here, we have a contiguous number of bytes >= len * available in our buffer starting at aq_writehead. */ alq->aq_getpost.ae_data = alq->aq_entbuf + alq->aq_writehead; alq->aq_getpost.ae_bytesused = len; return (&alq->aq_getpost); } struct ale * alq_get(struct alq *alq, int flags) { /* Should only be called in fixed length message (legacy) mode. */ KASSERT((alq->aq_flags & AQ_LEGACY), ("%s: fixed length get on variable length queue", __func__)); return (alq_getn(alq, alq->aq_entlen, flags)); } void alq_post_flags(struct alq *alq, struct ale *ale, int flags) { int activate; void *waitchan; activate = 0; if (ale->ae_bytesused > 0) { if (!(alq->aq_flags & AQ_ACTIVE) && !(flags & ALQ_NOACTIVATE)) { alq->aq_flags |= AQ_ACTIVE; activate = 1; } alq->aq_writehead += ale->ae_bytesused; alq->aq_freebytes -= ale->ae_bytesused; /* Wrap aq_writehead if we filled to the end of the buffer. */ if (alq->aq_writehead == alq->aq_buflen) alq->aq_writehead = 0; KASSERT((alq->aq_writehead >= 0 && alq->aq_writehead < alq->aq_buflen), ("%s: aq_writehead < 0 || aq_writehead >= aq_buflen", __func__)); KASSERT((HAS_PENDING_DATA(alq)), ("%s: queue empty!", __func__)); } /* * If there are waiters, we need to signal the waiting threads after we * complete our work. The alq ptr is used as a wait channel for threads * requiring resources to be freed up. In the AQ_ORDERED case, threads * are not allowed to concurrently compete for resources in the * alq_getn() while loop, so we use a different wait channel in this case. */ if (alq->aq_waiters > 0) { if (alq->aq_flags & AQ_ORDERED) waitchan = &alq->aq_waiters; else waitchan = alq; } else waitchan = NULL; ALQ_UNLOCK(alq); if (activate) { ALD_LOCK(); ald_activate(alq); ALD_UNLOCK(); } /* NB: We rely on wakeup_one waking threads in a FIFO manner. */ if (waitchan != NULL) wakeup_one(waitchan); } void alq_flush(struct alq *alq) { int needwakeup = 0; ALD_LOCK(); ALQ_LOCK(alq); /* * Pull the lever iff there is data to flush and we're * not already in the middle of a flush operation. */ if (HAS_PENDING_DATA(alq) && !(alq->aq_flags & AQ_FLUSHING)) { if (alq->aq_flags & AQ_ACTIVE) ald_deactivate(alq); ALD_UNLOCK(); needwakeup = alq_doio(alq); } else ALD_UNLOCK(); ALQ_UNLOCK(alq); if (needwakeup) wakeup_one(alq); } /* * Flush remaining data, close the file and free all resources. */ void alq_close(struct alq *alq) { /* Only flush and destroy alq if not already shutting down. */ if (ald_rem(alq) == 0) alq_destroy(alq); } static int alq_load_handler(module_t mod, int what, void *arg) { int ret; ret = 0; switch (what) { case MOD_LOAD: case MOD_SHUTDOWN: break; case MOD_QUIESCE: ALD_LOCK(); /* Only allow unload if there are no open queues. */ if (LIST_FIRST(&ald_queues) == NULL) { ald_shutingdown = 1; ALD_UNLOCK(); EVENTHANDLER_DEREGISTER(shutdown_pre_sync, alq_eventhandler_tag); ald_shutdown(NULL, 0); mtx_destroy(&ald_mtx); } else { ALD_UNLOCK(); ret = EBUSY; } break; case MOD_UNLOAD: /* If MOD_QUIESCE failed we must fail here too. */ if (ald_shutingdown == 0) ret = EBUSY; break; default: ret = EINVAL; break; } return (ret); } static moduledata_t alq_mod = { "alq", alq_load_handler, NULL }; DECLARE_MODULE(alq, alq_mod, SI_SUB_LAST, SI_ORDER_ANY); MODULE_VERSION(alq, 1);