The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/cam/cam_queue.h

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    1 /*-
    2  * CAM request queue management definitions.
    3  *
    4  * Copyright (c) 1997 Justin T. Gibbs.
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions, and the following disclaimer,
   12  *    without modification, immediately at the beginning of the file.
   13  * 2. The name of the author may not be used to endorse or promote products
   14  *    derived from this software without specific prior written permission.
   15  *
   16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   19  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
   20  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   26  * SUCH DAMAGE.
   27  *
   28  * $FreeBSD: releng/10.1/sys/cam/cam_queue.h 260387 2014-01-07 01:51:48Z scottl $
   29  */
   30 
   31 #ifndef _CAM_CAM_QUEUE_H
   32 #define _CAM_CAM_QUEUE_H 1
   33 
   34 #ifdef _KERNEL
   35 
   36 #include <sys/lock.h>
   37 #include <sys/mutex.h>
   38 #include <sys/queue.h>
   39 #include <cam/cam.h>
   40 
   41 /*
   42  * This structure implements a heap based priority queue.  The queue
   43  * assumes that the objects stored in it begin with a cam_qentry
   44  * structure holding the priority information used to sort the objects.
   45  * This structure is opaque to clients (outside of the XPT layer) to allow
   46  * the implementation to change without affecting them.
   47  */
   48 struct camq {
   49         cam_pinfo **queue_array;
   50         int        array_size;
   51         int        entries;
   52         u_int32_t  generation;
   53         u_int32_t  qfrozen_cnt;
   54 };
   55 
   56 TAILQ_HEAD(ccb_hdr_tailq, ccb_hdr);
   57 LIST_HEAD(ccb_hdr_list, ccb_hdr);
   58 SLIST_HEAD(ccb_hdr_slist, ccb_hdr);
   59 
   60 struct cam_ccbq {
   61         struct  camq queue;
   62         struct ccb_hdr_tailq    queue_extra_head;
   63         int     queue_extra_entries;
   64         int     total_openings;
   65         int     devq_openings;
   66         int     dev_openings;
   67         int     dev_active;
   68         int     held;
   69 };
   70 
   71 struct cam_ed;
   72 
   73 struct cam_devq {
   74         struct mtx       send_mtx;
   75         struct camq      send_queue;
   76         int              send_openings;
   77         int              send_active;
   78 };
   79 
   80 
   81 struct cam_devq *cam_devq_alloc(int devices, int openings);
   82 
   83 int              cam_devq_init(struct cam_devq *devq, int devices,
   84                                int openings);
   85 
   86 void             cam_devq_free(struct cam_devq *devq);
   87 
   88 u_int32_t        cam_devq_resize(struct cam_devq *camq, int openings);
   89         
   90 /*
   91  * Allocate a cam_ccb_queue structure and initialize it.
   92  */
   93 struct cam_ccbq *cam_ccbq_alloc(int openings);
   94 
   95 u_int32_t       cam_ccbq_resize(struct cam_ccbq *ccbq, int devices);
   96 
   97 int             cam_ccbq_init(struct cam_ccbq *ccbq, int openings);
   98 
   99 void            cam_ccbq_free(struct cam_ccbq *ccbq);
  100 
  101 void            cam_ccbq_fini(struct cam_ccbq *ccbq);
  102 
  103 /*
  104  * Allocate and initialize a cam_queue structure.
  105  */
  106 struct camq     *camq_alloc(int size);
  107 
  108 /*
  109  * Resize a cam queue
  110  */
  111 u_int32_t       camq_resize(struct camq *queue, int new_size);
  112 
  113 /* 
  114  * Initialize a camq structure.  Return 0 on success, 1 on failure.
  115  */
  116 int             camq_init(struct camq *camq, int size);
  117 
  118 /*
  119  * Free a cam_queue structure.  This should only be called if a controller
  120  * driver failes somehow during its attach routine or is unloaded and has
  121  * obtained a cam_queue structure.
  122  */
  123 void            camq_free(struct camq *queue);
  124 
  125 /*
  126  * Finialize any internal storage or state of a cam_queue.
  127  */
  128 void            camq_fini(struct camq *queue);
  129 
  130 /*
  131  * cam_queue_insert: Given a CAM queue with at least one open spot,
  132  * insert the new entry maintaining order.
  133  */
  134 void            camq_insert(struct camq *queue, cam_pinfo *new_entry);
  135 
  136 /*
  137  * camq_remove: Remove and arbitrary entry from the queue maintaining
  138  * queue order.
  139  */
  140 cam_pinfo       *camq_remove(struct camq *queue, int index);
  141 #define CAMQ_HEAD 1     /* Head of queue index */
  142 
  143 /* Index the first element in the heap */
  144 #define CAMQ_GET_HEAD(camq) ((camq)->queue_array[CAMQ_HEAD])
  145 
  146 /* Get the first element priority. */
  147 #define CAMQ_GET_PRIO(camq) (((camq)->entries > 0) ?                    \
  148                             ((camq)->queue_array[CAMQ_HEAD]->priority) : 0)
  149 
  150 /*
  151  * camq_change_priority: Raise or lower the priority of an entry
  152  * maintaining queue order.
  153  */
  154 void            camq_change_priority(struct camq *queue, int index,
  155                                      u_int32_t new_priority);
  156 
  157 static __inline int
  158 cam_ccbq_pending_ccb_count(struct cam_ccbq *ccbq);
  159 
  160 static __inline void
  161 cam_ccbq_take_opening(struct cam_ccbq *ccbq);
  162 
  163 static __inline void
  164 cam_ccbq_insert_ccb(struct cam_ccbq *ccbq, union ccb *new_ccb);
  165 
  166 static __inline void
  167 cam_ccbq_remove_ccb(struct cam_ccbq *ccbq, union ccb *ccb);
  168 
  169 static __inline union ccb *
  170 cam_ccbq_peek_ccb(struct cam_ccbq *ccbq, int index);
  171 
  172 static __inline void
  173 cam_ccbq_send_ccb(struct cam_ccbq *queue, union ccb *send_ccb);
  174 
  175 static __inline void
  176 cam_ccbq_ccb_done(struct cam_ccbq *ccbq, union ccb *done_ccb);
  177 
  178 static __inline void
  179 cam_ccbq_release_opening(struct cam_ccbq *ccbq);
  180 
  181 
  182 static __inline int
  183 cam_ccbq_pending_ccb_count(struct cam_ccbq *ccbq)
  184 {
  185         return (ccbq->queue.entries + ccbq->queue_extra_entries);
  186 }
  187 
  188 static __inline void
  189 cam_ccbq_take_opening(struct cam_ccbq *ccbq)
  190 {
  191         ccbq->devq_openings--;
  192         ccbq->held++;
  193 }
  194 
  195 static __inline void
  196 cam_ccbq_insert_ccb(struct cam_ccbq *ccbq, union ccb *new_ccb)
  197 {
  198         struct ccb_hdr *old_ccb;
  199         struct camq *queue = &ccbq->queue;
  200 
  201         ccbq->held--;
  202 
  203         /*
  204          * If queue is already full, try to resize.
  205          * If resize fail, push CCB with lowest priority out to the TAILQ.
  206          */
  207         if (queue->entries == queue->array_size &&
  208             camq_resize(&ccbq->queue, queue->array_size * 2) != CAM_REQ_CMP) {
  209                 old_ccb = (struct ccb_hdr *)camq_remove(queue, queue->entries);
  210                 TAILQ_INSERT_HEAD(&ccbq->queue_extra_head, old_ccb,
  211                     xpt_links.tqe);
  212                 old_ccb->pinfo.index = CAM_EXTRAQ_INDEX;
  213                 ccbq->queue_extra_entries++;
  214         }
  215 
  216         camq_insert(queue, &new_ccb->ccb_h.pinfo);
  217 }
  218 
  219 static __inline void
  220 cam_ccbq_remove_ccb(struct cam_ccbq *ccbq, union ccb *ccb)
  221 {
  222         struct ccb_hdr *cccb, *bccb;
  223         struct camq *queue = &ccbq->queue;
  224 
  225         /* If the CCB is on the TAILQ, remove it from there. */
  226         if (ccb->ccb_h.pinfo.index == CAM_EXTRAQ_INDEX) {
  227                 TAILQ_REMOVE(&ccbq->queue_extra_head, &ccb->ccb_h,
  228                     xpt_links.tqe);
  229                 ccb->ccb_h.pinfo.index = CAM_UNQUEUED_INDEX;
  230                 ccbq->queue_extra_entries--;
  231                 return;
  232         }
  233 
  234         camq_remove(queue, ccb->ccb_h.pinfo.index);
  235 
  236         /*
  237          * If there are some CCBs on TAILQ, find the best one and move it
  238          * to the emptied space in the queue.
  239          */
  240         bccb = TAILQ_FIRST(&ccbq->queue_extra_head);
  241         if (bccb == NULL)
  242                 return;
  243         TAILQ_FOREACH(cccb, &ccbq->queue_extra_head, xpt_links.tqe) {
  244                 if (bccb->pinfo.priority > cccb->pinfo.priority ||
  245                     (bccb->pinfo.priority == cccb->pinfo.priority &&
  246                      GENERATIONCMP(bccb->pinfo.generation, >,
  247                       cccb->pinfo.generation)))
  248                         bccb = cccb;
  249         }
  250         TAILQ_REMOVE(&ccbq->queue_extra_head, bccb, xpt_links.tqe);
  251         ccbq->queue_extra_entries--;
  252         camq_insert(queue, &bccb->pinfo);
  253 }
  254 
  255 static __inline union ccb *
  256 cam_ccbq_peek_ccb(struct cam_ccbq *ccbq, int index)
  257 {
  258         return((union ccb *)ccbq->queue.queue_array[index]);
  259 }
  260 
  261 static __inline void
  262 cam_ccbq_send_ccb(struct cam_ccbq *ccbq, union ccb *send_ccb)
  263 {
  264 
  265         send_ccb->ccb_h.pinfo.index = CAM_ACTIVE_INDEX;
  266         ccbq->dev_active++;
  267         ccbq->dev_openings--;           
  268 }
  269 
  270 static __inline void
  271 cam_ccbq_ccb_done(struct cam_ccbq *ccbq, union ccb *done_ccb)
  272 {
  273 
  274         ccbq->dev_active--;
  275         ccbq->dev_openings++;   
  276         ccbq->held++;
  277 }
  278 
  279 static __inline void
  280 cam_ccbq_release_opening(struct cam_ccbq *ccbq)
  281 {
  282         ccbq->held--;
  283         ccbq->devq_openings++;
  284 }
  285 
  286 #endif /* _KERNEL */
  287 #endif  /* _CAM_CAM_QUEUE_H */

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