pb: don't keep checking buffers after first busy

If we assume busy buffers are added to the list in order its unlikely
we'd fine one after the first busy one that isn't busy.

src/gallium/auxiliary/pipebuffer/pb_bufmgr_cache.c

@@ -222,7 +222,7 @@ pb_cache_buffer_vtbl = {
 };
 
 
-static INLINE boolean
+static INLINE int
 pb_cache_is_buffer_compat(struct pb_cache_buffer *buf,  
                           pb_size size,
                           const struct pb_desc *desc)
@@ -230,26 +230,26 @@ pb_cache_is_buffer_compat(struct pb_cache_buffer *buf,
    void *map;
 
    if(buf->base.base.size < size)
-      return FALSE;
+      return 0;
 
    /* be lenient with size */
    if(buf->base.base.size >= 2*size)
-      return FALSE;
+      return 0;
    
    if(!pb_check_alignment(desc->alignment, buf->base.base.alignment))
-      return FALSE;
+      return 0;
    
    if(!pb_check_usage(desc->usage, buf->base.base.usage))
-      return FALSE;
+      return 0;
 
    map = pb_map(buf->buffer, PB_USAGE_DONTBLOCK, NULL);
    if (!map) {
-      return FALSE;
+      return -1;
    }
 
    pb_unmap(buf->buffer);
    
-   return TRUE;
+   return 1;
 }
 
 
@@ -263,7 +263,8 @@ pb_cache_manager_create_buffer(struct pb_manager *_mgr,
    struct pb_cache_buffer *curr_buf;
    struct list_head *curr, *next;
    int64_t now;
-   
+   int ret = 0;
+
    pipe_mutex_lock(mgr->mutex);
 
    buf = NULL;
@@ -274,25 +275,30 @@ pb_cache_manager_create_buffer(struct pb_manager *_mgr,
    now = os_time_get();
    while(curr != &mgr->delayed) {
       curr_buf = LIST_ENTRY(struct pb_cache_buffer, curr, head);
-      if(!buf && pb_cache_is_buffer_compat(curr_buf, size, desc))
-	 buf = curr_buf;
+      if(!buf && (ret = pb_cache_is_buffer_compat(curr_buf, size, desc) > 0))
+         buf = curr_buf;
       else if(os_time_timeout(curr_buf->start, curr_buf->end, now))
-	 _pb_cache_buffer_destroy(curr_buf);
+         _pb_cache_buffer_destroy(curr_buf);
       else
          /* This buffer (and all hereafter) are still hot in cache */
          break;
+      if (ret == -1)
+         break;
       curr = next; 
       next = curr->next;
    }
 
    /* keep searching in the hot buffers */
-   if(!buf) {
+   if(!buf && ret != -1) {
       while(curr != &mgr->delayed) {
          curr_buf = LIST_ENTRY(struct pb_cache_buffer, curr, head);
-         if(pb_cache_is_buffer_compat(curr_buf, size, desc)) {
+         ret = pb_cache_is_buffer_compat(curr_buf, size, desc);
+         if (ret > 0) {
             buf = curr_buf;
             break;
          }
+         if (ret == -1)
+            break;
          /* no need to check the timeout here */
          curr = next;
          next = curr->next;