text: /*
   * 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: src/sys/cam/cam_queue.c,v 1.7 2003/06/10 17:50:20 obrien Exp $");
  
  #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;
  	}
  }
  