cb58805943
Add description for what each of the parameters are to the cam_sim_alloc call. Add some additional context for the mtx and queue parameters to explain what special values passed in mean. MFC After: 3 days Reviewed by: mav@ Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D30115
225 lines
6.6 KiB
C
225 lines
6.6 KiB
C
/*-
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* Common functions for SCSI Interface Modules (SIMs).
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*
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 1997 Justin T. Gibbs.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions, and the following disclaimer,
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* without modification, immediately at the beginning of the file.
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* 2. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
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* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/malloc.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/bus.h>
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#include <cam/cam.h>
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#include <cam/cam_ccb.h>
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#include <cam/cam_sim.h>
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#include <cam/cam_queue.h>
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#include <cam/cam_xpt.h>
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#define CAM_PATH_ANY (u_int32_t)-1
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static MALLOC_DEFINE(M_CAMSIM, "CAM SIM", "CAM SIM buffers");
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static struct mtx cam_sim_free_mtx;
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MTX_SYSINIT(cam_sim_free_init, &cam_sim_free_mtx, "CAM SIM free lock", MTX_DEF);
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struct cam_devq *
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cam_simq_alloc(u_int32_t max_sim_transactions)
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{
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return (cam_devq_alloc(/*size*/0, max_sim_transactions));
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}
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void
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cam_simq_free(struct cam_devq *devq)
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{
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cam_devq_free(devq);
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}
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/**
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* @brief allocate a new sim and fill in the details
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*
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* A Storage Interface Module (SIM) is the interface between CAM and
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* hardware. SIM receives CCBs from CAM via @p sim_action callback and
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* translates them into DMA or other hardware transactions. During system
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* dumps, it can be polled with the @p sim_poll callback. CCB processing is
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* terminated by calling @c xpt_done().
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*
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* The @p mtx acts as a perimeter lock for the SIM. All calls into the SIM's
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* @p sim_action are made with this lock held. It is also used to hold/release
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* a SIM, managing its reference count. When the lock is NULL, the SIM is 100%
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* responsible for locking (and the reference counting is done with a shared
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* lock.
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*
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* The cam_devq passed in (@c queue) is used to arbitrate the number of
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* outstanding transactions to the SIM. For HBAs that have global limits shared
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* between the different buses, the same devq should be specified for each bus
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* attached to the SIM.
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*
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* @param sim_action Function to call to process CCBs
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* @param sim_poll Function to poll the hardware for completions
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* @param sim_name Name of SIM class
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* @param softc Software context associated with the SIM
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* @param unit Unit number of SIM
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* @param mtx Mutex to lock while interacting with the SIM, or NULL
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* for a SIM that handle its own locking to enable multi
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* queue support.
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* @param max_dev_transactions Maximum number of concurrent untagged
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* transactions possible
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* @param max_tagged_dev_transactions Maximum number of concurrent tagged
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* transactions possible.
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* @param queue The cam_devq to use for this SIM.
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*/
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struct cam_sim *
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cam_sim_alloc(sim_action_func sim_action, sim_poll_func sim_poll,
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const char *sim_name, void *softc, u_int32_t unit,
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struct mtx *mtx, int max_dev_transactions,
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int max_tagged_dev_transactions, struct cam_devq *queue)
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{
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struct cam_sim *sim;
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sim = malloc(sizeof(struct cam_sim), M_CAMSIM, M_ZERO | M_NOWAIT);
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if (sim == NULL)
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return (NULL);
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sim->sim_action = sim_action;
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sim->sim_poll = sim_poll;
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sim->sim_name = sim_name;
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sim->softc = softc;
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sim->path_id = CAM_PATH_ANY;
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sim->sim_dev = NULL; /* set only by cam_sim_alloc_dev */
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sim->unit_number = unit;
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sim->bus_id = 0; /* set in xpt_bus_register */
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sim->max_tagged_dev_openings = max_tagged_dev_transactions;
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sim->max_dev_openings = max_dev_transactions;
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sim->flags = 0;
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sim->refcount = 1;
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sim->devq = queue;
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sim->mtx = mtx;
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callout_init(&sim->callout, 1);
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return (sim);
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}
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struct cam_sim *
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cam_sim_alloc_dev(sim_action_func sim_action, sim_poll_func sim_poll,
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const char *sim_name, void *softc, device_t dev,
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struct mtx *mtx, int max_dev_transactions,
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int max_tagged_dev_transactions, struct cam_devq *queue)
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{
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struct cam_sim *sim;
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KASSERT(dev != NULL, ("%s: dev is null for sim_name %s softc %p\n",
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__func__, sim_name, softc));
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sim = cam_sim_alloc(sim_action, sim_poll, sim_name, softc,
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device_get_unit(dev), mtx, max_dev_transactions,
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max_tagged_dev_transactions, queue);
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if (sim != NULL)
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sim->sim_dev = dev;
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return (sim);
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}
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void
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cam_sim_free(struct cam_sim *sim, int free_devq)
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{
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struct mtx *mtx;
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int error;
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if (sim->mtx == NULL) {
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mtx = &cam_sim_free_mtx;
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mtx_lock(mtx);
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} else {
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mtx = sim->mtx;
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mtx_assert(mtx, MA_OWNED);
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}
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KASSERT(sim->refcount >= 1, ("sim->refcount >= 1"));
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sim->refcount--;
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if (sim->refcount > 0) {
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error = msleep(sim, mtx, PRIBIO, "simfree", 0);
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KASSERT(error == 0, ("invalid error value for msleep(9)"));
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}
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KASSERT(sim->refcount == 0, ("sim->refcount == 0"));
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if (mtx == &cam_sim_free_mtx) /* sim->mtx == NULL */
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mtx_unlock(mtx);
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if (free_devq)
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cam_simq_free(sim->devq);
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free(sim, M_CAMSIM);
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}
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void
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cam_sim_release(struct cam_sim *sim)
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{
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struct mtx *mtx;
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if (sim->mtx == NULL)
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mtx = &cam_sim_free_mtx;
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else if (!mtx_owned(sim->mtx))
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mtx = sim->mtx;
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else
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mtx = NULL; /* We hold the lock. */
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if (mtx)
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mtx_lock(mtx);
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KASSERT(sim->refcount >= 1, ("sim->refcount >= 1"));
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sim->refcount--;
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if (sim->refcount == 0)
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wakeup(sim);
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if (mtx)
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mtx_unlock(mtx);
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}
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void
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cam_sim_hold(struct cam_sim *sim)
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{
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struct mtx *mtx;
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if (sim->mtx == NULL)
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mtx = &cam_sim_free_mtx;
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else if (!mtx_owned(sim->mtx))
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mtx = sim->mtx;
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else
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mtx = NULL; /* We hold the lock. */
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if (mtx)
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mtx_lock(mtx);
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KASSERT(sim->refcount >= 1, ("sim->refcount >= 1"));
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sim->refcount++;
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if (mtx)
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mtx_unlock(mtx);
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}
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void
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cam_sim_set_path(struct cam_sim *sim, u_int32_t path_id)
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{
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sim->path_id = path_id;
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}
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