FreeBSD/Linux Kernel Cross Reference
sys/cam/cam_queue.c

     /*
      * CAM request queue management functions.
      *
      * Copyright (c) 1997 Justin T. Gibbs.
      * All rights reserved.
      *
      * 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, this list of conditions, and the following disclaimer,
     *    without modification, immediately at the beginning of the file.
     * 2. The name of the author may not be used to endorse or promote products
     *    derived from this software without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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: releng/5.3/sys/cam/cam_queue.c 116161 2003-06-10 17:50:20Z obrien $");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/types.h>
    #include <sys/malloc.h>
    
    #include <cam/cam.h>
    #include <cam/cam_ccb.h>
    #include <cam/cam_queue.h>
    #include <cam/cam_debug.h>
    
    static __inline int
                    queue_cmp(cam_pinfo **queue_array, int i, int j);
    static __inline void
                    swap(cam_pinfo **queue_array, int i, int j);
    static void     heap_up(cam_pinfo **queue_array, int new_index);
    static void     heap_down(cam_pinfo **queue_array, int index,
                              int last_index);
    
    struct camq *
    camq_alloc(int size)
    {
            struct camq *camq;
    
            camq = (struct camq *)malloc(sizeof(*camq), M_DEVBUF, M_NOWAIT);
            if (camq != NULL) {
                    if (camq_init(camq, size) != 0) {
                            free(camq, M_DEVBUF);
                            camq = NULL;
                    }
            }
            return (camq);
    }
            
    int
    camq_init(struct camq *camq, int size)
    {
            bzero(camq, sizeof(*camq));
            camq->array_size = size;
            if (camq->array_size != 0) {
                    camq->queue_array = (cam_pinfo**)malloc(size*sizeof(cam_pinfo*),
                                                            M_DEVBUF, M_NOWAIT);
                    if (camq->queue_array == NULL) {
                            printf("camq_init: - cannot malloc array!\n");
                            return (1);
                    }
                    /*
                     * Heap algorithms like everything numbered from 1, so
                     * offset our pointer into the heap array by one element.
                     */
                    camq->queue_array--;
            }
            return (0);
    }
    
    /*
     * Free a camq structure.  This should only be called if a controller
     * driver failes somehow during its attach routine or is unloaded and has
     * obtained a camq structure.  The XPT should ensure that the queue
     * is empty before calling this routine.
     */
    void
    camq_free(struct camq *queue)
    {
            if (queue != NULL) {
                    camq_fini(queue);
                    free(queue, M_DEVBUF);
            }
    }
   
   void
   camq_fini(struct camq *queue)
   {
           if (queue->queue_array != NULL) {
                   /*
                    * Heap algorithms like everything numbered from 1, so
                    * our pointer into the heap array is offset by one element.
                    */
                   queue->queue_array++;
                   free(queue->queue_array, M_DEVBUF);
           }
   }
   
   u_int32_t
   camq_resize(struct camq *queue, int new_size)
   {
           cam_pinfo **new_array;
   
   #ifdef DIAGNOSTIC
           if (new_size < queue->entries)
                   panic("camq_resize: New queue size can't accomodate "
                         "queued entries.");
   #endif
           new_array = (cam_pinfo **)malloc(new_size * sizeof(cam_pinfo *),
                                            M_DEVBUF, M_NOWAIT);
           if (new_array == NULL) {
                   /* Couldn't satisfy request */
                   return (CAM_RESRC_UNAVAIL);
           }
           /*
            * Heap algorithms like everything numbered from 1, so
            * remember that our pointer into the heap array is offset
            * by one element.
            */
           if (queue->queue_array != NULL) {
                   queue->queue_array++;
                   bcopy(queue->queue_array, new_array,
                         queue->entries * sizeof(cam_pinfo *));
                   free(queue->queue_array, M_DEVBUF);
           }
           queue->queue_array = new_array-1;
           queue->array_size = new_size;
           return (CAM_REQ_CMP);
   }
   
   /*
    * camq_insert: Given an array of cam_pinfo* elememnts with
    * the Heap(1, num_elements) property and array_size - num_elements >= 1,
    * output Heap(1, num_elements+1) including new_entry in the array.
    */
   void
   camq_insert(struct camq *queue, cam_pinfo *new_entry)
   {
   #ifdef DIAGNOSTIC
           if (queue->entries >= queue->array_size)
                   panic("camq_insert: Attempt to insert into a full queue");
   #endif
           queue->entries++;
           queue->queue_array[queue->entries] = new_entry;
           new_entry->index = queue->entries;
           if (queue->entries != 0)
                   heap_up(queue->queue_array, queue->entries);
   }
   
   /*
    * camq_remove:  Given an array of cam_pinfo* elevements with the
    * Heap(1, num_elements) property and an index such that 1 <= index <=
    * num_elements, remove that entry and restore the Heap(1, num_elements-1)
    * property.
    */
   cam_pinfo *
   camq_remove(struct camq *queue, int index)
   {
           cam_pinfo *removed_entry;
   
           if (index == 0 || index > queue->entries)
                   return (NULL);
           removed_entry = queue->queue_array[index];
           if (queue->entries != index) {
                   queue->queue_array[index] = queue->queue_array[queue->entries];
                   queue->queue_array[index]->index = index;
                   heap_down(queue->queue_array, index, queue->entries - 1);
           }
           removed_entry->index = CAM_UNQUEUED_INDEX;
           queue->entries--;
           return (removed_entry);
   }
   
   /*
    * camq_change_priority:  Given an array of cam_pinfo* elements with the
    * Heap(1, num_entries) property, an index such that 1 <= index <= num_elements,
    * and a new priority for the element at index, change the priority of
    * element index and restore the Heap(0, num_elements) property.
    */
   void
   camq_change_priority(struct camq *queue, int index, u_int32_t new_priority)
   {
           if (new_priority > queue->queue_array[index]->priority) {
                   queue->queue_array[index]->priority = new_priority;
                   heap_down(queue->queue_array, index, queue->entries);
           } else {
                   /* new_priority <= old_priority */
                   queue->queue_array[index]->priority = new_priority;
                   heap_up(queue->queue_array, index);
           }
   }
   
   struct cam_devq *
   cam_devq_alloc(int devices, int openings)
   {
           struct cam_devq *devq;
   
           devq = (struct cam_devq *)malloc(sizeof(*devq), M_DEVBUF, M_NOWAIT);
           if (devq == NULL) {
                   printf("cam_devq_alloc: - cannot malloc!\n");
                   return (NULL);
           }
           if (cam_devq_init(devq, devices, openings) != 0) {
                   free(devq, M_DEVBUF);
                   return (NULL);          
           }
           
           return (devq);
   }
   
   int
   cam_devq_init(struct cam_devq *devq, int devices, int openings)
   {
           bzero(devq, sizeof(*devq));
           if (camq_init(&devq->alloc_queue, devices) != 0) {
                   return (1);
           }
           if (camq_init(&devq->send_queue, devices) != 0) {
                   camq_fini(&devq->alloc_queue);
                   return (1);
           }
           devq->alloc_openings = openings;
           devq->alloc_active = 0;
           devq->send_openings = openings;
           devq->send_active = 0;  
           return (0);     
   }
   
   void
   cam_devq_free(struct cam_devq *devq)
   {
           camq_fini(&devq->alloc_queue);
           camq_fini(&devq->send_queue);
           free(devq, M_DEVBUF);
   }
   
   u_int32_t
   cam_devq_resize(struct cam_devq *camq, int devices)
   {
           u_int32_t retval;
   
           retval = camq_resize(&camq->alloc_queue, devices);
   
           if (retval == CAM_REQ_CMP)
                   retval = camq_resize(&camq->send_queue, devices);
   
           return (retval);
   }
   
   struct cam_ccbq *
   cam_ccbq_alloc(int openings)
   {
           struct cam_ccbq *ccbq;
   
           ccbq = (struct cam_ccbq *)malloc(sizeof(*ccbq), M_DEVBUF, M_NOWAIT);
           if (ccbq == NULL) {
                   printf("cam_ccbq_alloc: - cannot malloc!\n");
                   return (NULL);
           }
           if (cam_ccbq_init(ccbq, openings) != 0) {
                   free(ccbq, M_DEVBUF);
                   return (NULL);          
           }
           
           return (ccbq);
   }
   
   void
   cam_ccbq_free(struct cam_ccbq *ccbq)
   {
           if (ccbq) {
                   camq_fini(&ccbq->queue);
                   free(ccbq, M_DEVBUF);
           }
   }
   
   u_int32_t
   cam_ccbq_resize(struct cam_ccbq *ccbq, int new_size)
   {
           int delta;
           int space_left;
   
           delta = new_size - (ccbq->dev_active + ccbq->dev_openings);
           space_left = new_size
               - ccbq->queue.entries
               - ccbq->held
               - ccbq->dev_active;
   
           /*
            * Only attempt to change the underlying queue size if we are
            * shrinking it and there is space for all outstanding entries
            * in the new array or we have been requested to grow the array.
            * We don't fail in the case where we can't reduce the array size,
            * but clients that care that the queue be "garbage collected"
            * should detect this condition and call us again with the
            * same size once the outstanding entries have been processed.
            */
           if (space_left < 0
            || camq_resize(&ccbq->queue, new_size) == CAM_REQ_CMP) {
                   ccbq->devq_openings += delta;
                   ccbq->dev_openings += delta;
                   return (CAM_REQ_CMP);
           } else {
                   return (CAM_RESRC_UNAVAIL);
           }
   }
   
   int
   cam_ccbq_init(struct cam_ccbq *ccbq, int openings)
   {
           bzero(ccbq, sizeof(*ccbq));
           if (camq_init(&ccbq->queue, openings) != 0) {
                   return (1);
           }
           ccbq->devq_openings = openings;
           ccbq->dev_openings = openings;  
           TAILQ_INIT(&ccbq->active_ccbs);
           return (0);
   }
   
   /*
    * Heap routines for manipulating CAM queues.
    */
   /*
    * queue_cmp: Given an array of cam_pinfo* elements and indexes i
    * and j, return less than 0, 0, or greater than 0 if i is less than,
    * equal too, or greater than j respectively.
    */
   static __inline int
   queue_cmp(cam_pinfo **queue_array, int i, int j)
   {
           if (queue_array[i]->priority == queue_array[j]->priority)
                   return (  queue_array[i]->generation
                           - queue_array[j]->generation );
           else
                   return (  queue_array[i]->priority
                           - queue_array[j]->priority );
   }
   
   /*
    * swap: Given an array of cam_pinfo* elements and indexes i and j,
    * exchange elements i and j.
    */
   static __inline void
   swap(cam_pinfo **queue_array, int i, int j)
   {
           cam_pinfo *temp_qentry;
   
           temp_qentry = queue_array[j];
           queue_array[j] = queue_array[i];
           queue_array[i] = temp_qentry;
           queue_array[j]->index = j;
           queue_array[i]->index = i;
   }
   
   /*
    * heap_up:  Given an array of cam_pinfo* elements with the
    * Heap(1, new_index-1) property and a new element in location
    * new_index, output Heap(1, new_index).
    */
   static void
   heap_up(cam_pinfo **queue_array, int new_index)
   {
           int child;
           int parent;
   
           child = new_index;
   
           while (child != 1) {
   
                   parent = child >> 1;
                   if (queue_cmp(queue_array, parent, child) <= 0)
                           break;
                   swap(queue_array, parent, child);
                   child = parent;
           }
   }
   
   /*
    * heap_down:  Given an array of cam_pinfo* elements with the
    * Heap(index + 1, num_entries) property with index containing
    * an unsorted entry, output Heap(index, num_entries).
    */
   static void
   heap_down(cam_pinfo **queue_array, int index, int num_entries)
   {
           int child;
           int parent;
           
           parent = index;
           child = parent << 1;
           for (; child <= num_entries; child = parent << 1) {
   
                   if (child < num_entries) {
                           /* child+1 is the right child of parent */
                           if (queue_cmp(queue_array, child + 1, child) < 0)
                                   child++;
                   }
                   /* child is now the least child of parent */
                   if (queue_cmp(queue_array, parent, child) <= 0)
                           break;
                   swap(queue_array, child, parent);
                   parent = child;
           }
   }

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