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

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    1 /*-
    2  * CAM request queue management functions.
    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 
   29 #include <sys/cdefs.h>
   30 __FBSDID("$FreeBSD$");
   31 
   32 #include <sys/param.h>
   33 #include <sys/systm.h>
   34 #include <sys/types.h>
   35 #include <sys/malloc.h>
   36 #include <sys/kernel.h>
   37 
   38 #include <cam/cam.h>
   39 #include <cam/cam_ccb.h>
   40 #include <cam/cam_queue.h>
   41 #include <cam/cam_debug.h>
   42 
   43 MALLOC_DEFINE(M_CAMQ, "CAM queue", "CAM queue buffers");
   44 MALLOC_DEFINE(M_CAMDEVQ, "CAM dev queue", "CAM dev queue buffers");
   45 MALLOC_DEFINE(M_CAMCCBQ, "CAM ccb queue", "CAM ccb queue buffers");
   46 
   47 static __inline int
   48                 queue_cmp(cam_pinfo **queue_array, int i, int j);
   49 static __inline void
   50                 swap(cam_pinfo **queue_array, int i, int j);
   51 static void     heap_up(cam_pinfo **queue_array, int new_index);
   52 static void     heap_down(cam_pinfo **queue_array, int index,
   53                           int last_index);
   54 
   55 struct camq *
   56 camq_alloc(int size)
   57 {
   58         struct camq *camq;
   59 
   60         camq = (struct camq *)malloc(sizeof(*camq), M_CAMQ, M_NOWAIT);
   61         if (camq != NULL) {
   62                 if (camq_init(camq, size) != 0) {
   63                         free(camq, M_CAMQ);
   64                         camq = NULL;
   65                 }
   66         }
   67         return (camq);
   68 }
   69         
   70 int
   71 camq_init(struct camq *camq, int size)
   72 {
   73         bzero(camq, sizeof(*camq));
   74         camq->array_size = size;
   75         if (camq->array_size != 0) {
   76                 camq->queue_array = (cam_pinfo**)malloc(size*sizeof(cam_pinfo*),
   77                                                         M_CAMQ, M_NOWAIT);
   78                 if (camq->queue_array == NULL) {
   79                         printf("camq_init: - cannot malloc array!\n");
   80                         return (1);
   81                 }
   82                 /*
   83                  * Heap algorithms like everything numbered from 1, so
   84                  * offset our pointer into the heap array by one element.
   85                  */
   86                 camq->queue_array--;
   87         }
   88         return (0);
   89 }
   90 
   91 /*
   92  * Free a camq structure.  This should only be called if a controller
   93  * driver failes somehow during its attach routine or is unloaded and has
   94  * obtained a camq structure.  The XPT should ensure that the queue
   95  * is empty before calling this routine.
   96  */
   97 void
   98 camq_free(struct camq *queue)
   99 {
  100         if (queue != NULL) {
  101                 camq_fini(queue);
  102                 free(queue, M_CAMQ);
  103         }
  104 }
  105 
  106 void
  107 camq_fini(struct camq *queue)
  108 {
  109         if (queue->queue_array != NULL) {
  110                 /*
  111                  * Heap algorithms like everything numbered from 1, so
  112                  * our pointer into the heap array is offset by one element.
  113                  */
  114                 queue->queue_array++;
  115                 free(queue->queue_array, M_CAMQ);
  116         }
  117 }
  118 
  119 u_int32_t
  120 camq_resize(struct camq *queue, int new_size)
  121 {
  122         cam_pinfo **new_array;
  123 
  124 #ifdef DIAGNOSTIC
  125         if (new_size < queue->entries)
  126                 panic("camq_resize: New queue size can't accomodate "
  127                       "queued entries.");
  128 #endif
  129         new_array = (cam_pinfo **)malloc(new_size * sizeof(cam_pinfo *),
  130                                          M_CAMQ, M_NOWAIT);
  131         if (new_array == NULL) {
  132                 /* Couldn't satisfy request */
  133                 return (CAM_RESRC_UNAVAIL);
  134         }
  135         /*
  136          * Heap algorithms like everything numbered from 1, so
  137          * remember that our pointer into the heap array is offset
  138          * by one element.
  139          */
  140         if (queue->queue_array != NULL) {
  141                 queue->queue_array++;
  142                 bcopy(queue->queue_array, new_array,
  143                       queue->entries * sizeof(cam_pinfo *));
  144                 free(queue->queue_array, M_CAMQ);
  145         }
  146         queue->queue_array = new_array-1;
  147         queue->array_size = new_size;
  148         return (CAM_REQ_CMP);
  149 }
  150 
  151 /*
  152  * camq_insert: Given an array of cam_pinfo* elememnts with
  153  * the Heap(1, num_elements) property and array_size - num_elements >= 1,
  154  * output Heap(1, num_elements+1) including new_entry in the array.
  155  */
  156 void
  157 camq_insert(struct camq *queue, cam_pinfo *new_entry)
  158 {
  159 #ifdef DIAGNOSTIC
  160         if (queue->entries >= queue->array_size)
  161                 panic("camq_insert: Attempt to insert into a full queue");
  162 #endif
  163         queue->entries++;
  164         queue->queue_array[queue->entries] = new_entry;
  165         new_entry->index = queue->entries;
  166         if (queue->entries != 0)
  167                 heap_up(queue->queue_array, queue->entries);
  168 }
  169 
  170 /*
  171  * camq_remove:  Given an array of cam_pinfo* elevements with the
  172  * Heap(1, num_elements) property and an index such that 1 <= index <=
  173  * num_elements, remove that entry and restore the Heap(1, num_elements-1)
  174  * property.
  175  */
  176 cam_pinfo *
  177 camq_remove(struct camq *queue, int index)
  178 {
  179         cam_pinfo *removed_entry;
  180 
  181         if (index == 0 || index > queue->entries)
  182                 return (NULL);
  183         removed_entry = queue->queue_array[index];
  184         if (queue->entries != index) {
  185                 queue->queue_array[index] = queue->queue_array[queue->entries];
  186                 queue->queue_array[index]->index = index;
  187                 heap_down(queue->queue_array, index, queue->entries - 1);
  188         }
  189         removed_entry->index = CAM_UNQUEUED_INDEX;
  190         queue->entries--;
  191         return (removed_entry);
  192 }
  193 
  194 /*
  195  * camq_change_priority:  Given an array of cam_pinfo* elements with the
  196  * Heap(1, num_entries) property, an index such that 1 <= index <= num_elements,
  197  * and a new priority for the element at index, change the priority of
  198  * element index and restore the Heap(0, num_elements) property.
  199  */
  200 void
  201 camq_change_priority(struct camq *queue, int index, u_int32_t new_priority)
  202 {
  203         if (new_priority > queue->queue_array[index]->priority) {
  204                 queue->queue_array[index]->priority = new_priority;
  205                 heap_down(queue->queue_array, index, queue->entries);
  206         } else {
  207                 /* new_priority <= old_priority */
  208                 queue->queue_array[index]->priority = new_priority;
  209                 heap_up(queue->queue_array, index);
  210         }
  211 }
  212 
  213 struct cam_devq *
  214 cam_devq_alloc(int devices, int openings)
  215 {
  216         struct cam_devq *devq;
  217 
  218         devq = (struct cam_devq *)malloc(sizeof(*devq), M_CAMDEVQ, M_NOWAIT);
  219         if (devq == NULL) {
  220                 printf("cam_devq_alloc: - cannot malloc!\n");
  221                 return (NULL);
  222         }
  223         if (cam_devq_init(devq, devices, openings) != 0) {
  224                 free(devq, M_CAMDEVQ);
  225                 return (NULL);          
  226         }
  227         
  228         return (devq);
  229 }
  230 
  231 int
  232 cam_devq_init(struct cam_devq *devq, int devices, int openings)
  233 {
  234         bzero(devq, sizeof(*devq));
  235         if (camq_init(&devq->alloc_queue, devices) != 0) {
  236                 return (1);
  237         }
  238         if (camq_init(&devq->send_queue, devices) != 0) {
  239                 camq_fini(&devq->alloc_queue);
  240                 return (1);
  241         }
  242         devq->alloc_openings = openings;
  243         devq->alloc_active = 0;
  244         devq->send_openings = openings;
  245         devq->send_active = 0;  
  246         return (0);     
  247 }
  248 
  249 void
  250 cam_devq_free(struct cam_devq *devq)
  251 {
  252         camq_fini(&devq->alloc_queue);
  253         camq_fini(&devq->send_queue);
  254         free(devq, M_CAMDEVQ);
  255 }
  256 
  257 u_int32_t
  258 cam_devq_resize(struct cam_devq *camq, int devices)
  259 {
  260         u_int32_t retval;
  261 
  262         retval = camq_resize(&camq->alloc_queue, devices);
  263 
  264         if (retval == CAM_REQ_CMP)
  265                 retval = camq_resize(&camq->send_queue, devices);
  266 
  267         return (retval);
  268 }
  269 
  270 struct cam_ccbq *
  271 cam_ccbq_alloc(int openings)
  272 {
  273         struct cam_ccbq *ccbq;
  274 
  275         ccbq = (struct cam_ccbq *)malloc(sizeof(*ccbq), M_CAMCCBQ, M_NOWAIT);
  276         if (ccbq == NULL) {
  277                 printf("cam_ccbq_alloc: - cannot malloc!\n");
  278                 return (NULL);
  279         }
  280         if (cam_ccbq_init(ccbq, openings) != 0) {
  281                 free(ccbq, M_CAMCCBQ);
  282                 return (NULL);          
  283         }
  284         
  285         return (ccbq);
  286 }
  287 
  288 void
  289 cam_ccbq_free(struct cam_ccbq *ccbq)
  290 {
  291         if (ccbq) {
  292                 camq_fini(&ccbq->queue);
  293                 free(ccbq, M_CAMCCBQ);
  294         }
  295 }
  296 
  297 u_int32_t
  298 cam_ccbq_resize(struct cam_ccbq *ccbq, int new_size)
  299 {
  300         int delta;
  301         int space_left;
  302 
  303         delta = new_size - (ccbq->dev_active + ccbq->dev_openings);
  304         space_left = new_size
  305             - ccbq->queue.entries
  306             - ccbq->held
  307             - ccbq->dev_active;
  308 
  309         /*
  310          * Only attempt to change the underlying queue size if we are
  311          * shrinking it and there is space for all outstanding entries
  312          * in the new array or we have been requested to grow the array.
  313          * We don't fail in the case where we can't reduce the array size,
  314          * but clients that care that the queue be "garbage collected"
  315          * should detect this condition and call us again with the
  316          * same size once the outstanding entries have been processed.
  317          */
  318         if (space_left < 0
  319          || camq_resize(&ccbq->queue, new_size) == CAM_REQ_CMP) {
  320                 ccbq->devq_openings += delta;
  321                 ccbq->dev_openings += delta;
  322                 return (CAM_REQ_CMP);
  323         } else {
  324                 return (CAM_RESRC_UNAVAIL);
  325         }
  326 }
  327 
  328 int
  329 cam_ccbq_init(struct cam_ccbq *ccbq, int openings)
  330 {
  331         bzero(ccbq, sizeof(*ccbq));
  332         if (camq_init(&ccbq->queue, openings) != 0) {
  333                 return (1);
  334         }
  335         ccbq->devq_openings = openings;
  336         ccbq->dev_openings = openings;  
  337         TAILQ_INIT(&ccbq->active_ccbs);
  338         return (0);
  339 }
  340 
  341 /*
  342  * Heap routines for manipulating CAM queues.
  343  */
  344 /*
  345  * queue_cmp: Given an array of cam_pinfo* elements and indexes i
  346  * and j, return less than 0, 0, or greater than 0 if i is less than,
  347  * equal too, or greater than j respectively.
  348  */
  349 static __inline int
  350 queue_cmp(cam_pinfo **queue_array, int i, int j)
  351 {
  352         if (queue_array[i]->priority == queue_array[j]->priority)
  353                 return (  queue_array[i]->generation
  354                         - queue_array[j]->generation );
  355         else
  356                 return (  queue_array[i]->priority
  357                         - queue_array[j]->priority );
  358 }
  359 
  360 /*
  361  * swap: Given an array of cam_pinfo* elements and indexes i and j,
  362  * exchange elements i and j.
  363  */
  364 static __inline void
  365 swap(cam_pinfo **queue_array, int i, int j)
  366 {
  367         cam_pinfo *temp_qentry;
  368 
  369         temp_qentry = queue_array[j];
  370         queue_array[j] = queue_array[i];
  371         queue_array[i] = temp_qentry;
  372         queue_array[j]->index = j;
  373         queue_array[i]->index = i;
  374 }
  375 
  376 /*
  377  * heap_up:  Given an array of cam_pinfo* elements with the
  378  * Heap(1, new_index-1) property and a new element in location
  379  * new_index, output Heap(1, new_index).
  380  */
  381 static void
  382 heap_up(cam_pinfo **queue_array, int new_index)
  383 {
  384         int child;
  385         int parent;
  386 
  387         child = new_index;
  388 
  389         while (child != 1) {
  390 
  391                 parent = child >> 1;
  392                 if (queue_cmp(queue_array, parent, child) <= 0)
  393                         break;
  394                 swap(queue_array, parent, child);
  395                 child = parent;
  396         }
  397 }
  398 
  399 /*
  400  * heap_down:  Given an array of cam_pinfo* elements with the
  401  * Heap(index + 1, num_entries) property with index containing
  402  * an unsorted entry, output Heap(index, num_entries).
  403  */
  404 static void
  405 heap_down(cam_pinfo **queue_array, int index, int num_entries)
  406 {
  407         int child;
  408         int parent;
  409         
  410         parent = index;
  411         child = parent << 1;
  412         for (; child <= num_entries; child = parent << 1) {
  413 
  414                 if (child < num_entries) {
  415                         /* child+1 is the right child of parent */
  416                         if (queue_cmp(queue_array, child + 1, child) < 0)
  417                                 child++;
  418                 }
  419                 /* child is now the least child of parent */
  420                 if (queue_cmp(queue_array, parent, child) <= 0)
  421                         break;
  422                 swap(queue_array, child, parent);
  423                 parent = child;
  424         }
  425 }

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