KSB_START
cmd_q->sb_key = KSB_START + ccp->sb_start++;
cmd_q->sb_ctx = KSB_START + ccp->sb_start++;
return KSB_START + start;
bitmap_clear(ccp->sb, start - KSB_START, count);
#define KSB_COUNT (KSB_END - KSB_START + 1)