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

     /*-
      * CAM request queue management definitions.
      *
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * 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.
     *
     * $FreeBSD$
     */
    
    #ifndef _CAM_CAM_QUEUE_H
    #define _CAM_CAM_QUEUE_H 1
    
    #ifdef _KERNEL
    
    #include <sys/lock.h>
    #include <sys/mutex.h>
    #include <sys/queue.h>
    #include <cam/cam.h>
    
    /*
     * This structure implements a heap based priority queue.  The queue
     * assumes that the objects stored in it begin with a cam_qentry
     * structure holding the priority information used to sort the objects.
     * This structure is opaque to clients (outside of the XPT layer) to allow
     * the implementation to change without affecting them.
     */
    struct camq {
            cam_pinfo **queue_array;
            int        array_size;
            int        entries;
            u_int32_t  generation;
            u_int32_t  qfrozen_cnt;
    };
    
    TAILQ_HEAD(ccb_hdr_tailq, ccb_hdr);
    LIST_HEAD(ccb_hdr_list, ccb_hdr);
    SLIST_HEAD(ccb_hdr_slist, ccb_hdr);
    
    struct cam_ccbq {
            struct  camq queue;
            struct ccb_hdr_tailq    queue_extra_head;
            int     queue_extra_entries;
            int     total_openings;
            int     allocated;
            int     dev_openings;
            int     dev_active;
    };
    
    struct cam_ed;
    
    struct cam_devq {
            struct mtx       send_mtx;
            struct camq      send_queue;
            int              send_openings;
            int              send_active;
    };
    
    struct cam_devq *cam_devq_alloc(int devices, int openings);
    
    int              cam_devq_init(struct cam_devq *devq, int devices,
                                   int openings);
    
    void             cam_devq_free(struct cam_devq *devq);
    
    u_int32_t        cam_devq_resize(struct cam_devq *camq, int openings);
    
    /*
     * Allocate a cam_ccb_queue structure and initialize it.
     */
    struct cam_ccbq *cam_ccbq_alloc(int openings);
    
    u_int32_t       cam_ccbq_resize(struct cam_ccbq *ccbq, int devices);
    
    int             cam_ccbq_init(struct cam_ccbq *ccbq, int openings);
    
    void            cam_ccbq_free(struct cam_ccbq *ccbq);
   
   void            cam_ccbq_fini(struct cam_ccbq *ccbq);
   
   /*
    * Resize a cam queue
    */
   u_int32_t       camq_resize(struct camq *queue, int new_size);
   
   /* 
    * Initialize a camq structure.  Return 0 on success, 1 on failure.
    */
   int             camq_init(struct camq *camq, int size);
   
   /*
    * Finialize any internal storage or state of a cam_queue.
    */
   void            camq_fini(struct camq *queue);
   
   /*
    * cam_queue_insert: Given a CAM queue with at least one open spot,
    * insert the new entry maintaining order.
    */
   void            camq_insert(struct camq *queue, cam_pinfo *new_entry);
   
   /*
    * camq_remove: Remove and arbitrary entry from the queue maintaining
    * queue order.
    */
   cam_pinfo       *camq_remove(struct camq *queue, int index);
   #define CAMQ_HEAD 1     /* Head of queue index */
   
   /* Index the first element in the heap */
   #define CAMQ_GET_HEAD(camq) ((camq)->queue_array[CAMQ_HEAD])
   
   /* Get the first element priority. */
   #define CAMQ_GET_PRIO(camq) (((camq)->entries > 0) ?                    \
                               ((camq)->queue_array[CAMQ_HEAD]->priority) : 0)
   
   /*
    * camq_change_priority: Raise or lower the priority of an entry
    * maintaining queue order.
    */
   void            camq_change_priority(struct camq *queue, int index,
                                        u_int32_t new_priority);
   
   static __inline int
   cam_ccbq_pending_ccb_count(struct cam_ccbq *ccbq)
   {
           return (ccbq->queue.entries + ccbq->queue_extra_entries);
   }
   
   static __inline void
   cam_ccbq_take_opening(struct cam_ccbq *ccbq)
   {
   
           ccbq->allocated++;
   }
   
   static __inline void
   cam_ccbq_insert_ccb(struct cam_ccbq *ccbq, union ccb *new_ccb)
   {
           struct ccb_hdr *old_ccb;
           struct camq *queue = &ccbq->queue;
   
           KASSERT((new_ccb->ccb_h.func_code & XPT_FC_QUEUED) != 0 &&
               (new_ccb->ccb_h.func_code & XPT_FC_USER_CCB) == 0,
               ("%s: Cannot queue ccb %p func_code %#x", __func__, new_ccb,
                new_ccb->ccb_h.func_code));
   
           /*
            * If queue is already full, try to resize.
            * If resize fail, push CCB with lowest priority out to the TAILQ.
            */
           if (queue->entries == queue->array_size &&
               camq_resize(&ccbq->queue, queue->array_size * 2) != CAM_REQ_CMP) {
                   old_ccb = (struct ccb_hdr *)camq_remove(queue, queue->entries);
                   TAILQ_INSERT_HEAD(&ccbq->queue_extra_head, old_ccb,
                       xpt_links.tqe);
                   old_ccb->pinfo.index = CAM_EXTRAQ_INDEX;
                   ccbq->queue_extra_entries++;
           }
   
           camq_insert(queue, &new_ccb->ccb_h.pinfo);
   }
   
   static __inline void
   cam_ccbq_remove_ccb(struct cam_ccbq *ccbq, union ccb *ccb)
   {
           struct ccb_hdr *cccb, *bccb;
           struct camq *queue = &ccbq->queue;
           cam_pinfo *removed_entry __unused;
   
           /* If the CCB is on the TAILQ, remove it from there. */
           if (ccb->ccb_h.pinfo.index == CAM_EXTRAQ_INDEX) {
                   TAILQ_REMOVE(&ccbq->queue_extra_head, &ccb->ccb_h,
                       xpt_links.tqe);
                   ccb->ccb_h.pinfo.index = CAM_UNQUEUED_INDEX;
                   ccbq->queue_extra_entries--;
                   return;
           }
   
           removed_entry = camq_remove(queue, ccb->ccb_h.pinfo.index);
           KASSERT(removed_entry == &ccb->ccb_h.pinfo,
               ("%s: Removed wrong entry from queue (%p != %p)", __func__,
                removed_entry, &ccb->ccb_h.pinfo));
   
           /*
            * If there are some CCBs on TAILQ, find the best one and move it
            * to the emptied space in the queue.
            */
           bccb = TAILQ_FIRST(&ccbq->queue_extra_head);
           if (bccb == NULL)
                   return;
           TAILQ_FOREACH(cccb, &ccbq->queue_extra_head, xpt_links.tqe) {
                   if (bccb->pinfo.priority > cccb->pinfo.priority ||
                       (bccb->pinfo.priority == cccb->pinfo.priority &&
                        GENERATIONCMP(bccb->pinfo.generation, >,
                         cccb->pinfo.generation)))
                           bccb = cccb;
           }
           TAILQ_REMOVE(&ccbq->queue_extra_head, bccb, xpt_links.tqe);
           ccbq->queue_extra_entries--;
           camq_insert(queue, &bccb->pinfo);
   }
   
   static __inline union ccb *
   cam_ccbq_peek_ccb(struct cam_ccbq *ccbq, int index)
   {
           return((union ccb *)ccbq->queue.queue_array[index]);
   }
   
   static __inline void
   cam_ccbq_send_ccb(struct cam_ccbq *ccbq, union ccb *send_ccb)
   {
   
           send_ccb->ccb_h.pinfo.index = CAM_ACTIVE_INDEX;
           ccbq->dev_active++;
           ccbq->dev_openings--;
   }
   
   static __inline void
   cam_ccbq_ccb_done(struct cam_ccbq *ccbq, union ccb *done_ccb)
   {
   
           ccbq->dev_active--;
           ccbq->dev_openings++;
   }
   
   static __inline void
   cam_ccbq_release_opening(struct cam_ccbq *ccbq)
   {
   
           ccbq->allocated--;
   }
   
   #endif /* _KERNEL */
   #endif  /* _CAM_CAM_QUEUE_H */

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