Hi Gavin, kernel test robot noticed the following build warnings: [auto build test WARNING on mst-vhost/linux-next] [also build test WARNING on linus/master v6.9-rc5 next-20240424] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/Gavin-Shan/vhost-Drop-variable-last_avail_idx-in-vhost_get_vq_desc/20240423-112803 base: https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git linux-next patch link: https://lore.kernel.org/r/20240423032407.262329-4-gshan%40redhat.com patch subject: [PATCH 3/4] vhost: Improve vhost_get_avail_head() config: i386-randconfig-141-20240426 (https://download.01.org/0day-ci/archive/20240426/202404260448.g7F06v7M-lkp@xxxxxxxxx/config) compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot <lkp@xxxxxxxxx> | Closes: https://lore.kernel.org/oe-kbuild-all/202404260448.g7F06v7M-lkp@xxxxxxxxx/ smatch warnings: drivers/vhost/vhost.c:2614 vhost_get_vq_desc() warn: unsigned 'head' is never less than zero. drivers/vhost/vhost.c:2614 vhost_get_vq_desc() warn: error code type promoted to positive: 'head' vim +/head +2614 drivers/vhost/vhost.c 2581 2582 /* This looks in the virtqueue and for the first available buffer, and converts 2583 * it to an iovec for convenient access. Since descriptors consist of some 2584 * number of output then some number of input descriptors, it's actually two 2585 * iovecs, but we pack them into one and note how many of each there were. 2586 * 2587 * This function returns the descriptor number found, or vq->num (which is 2588 * never a valid descriptor number) if none was found. A negative code is 2589 * returned on error. */ 2590 int vhost_get_vq_desc(struct vhost_virtqueue *vq, 2591 struct iovec iov[], unsigned int iov_size, 2592 unsigned int *out_num, unsigned int *in_num, 2593 struct vhost_log *log, unsigned int *log_num) 2594 { 2595 struct vring_desc desc; 2596 unsigned int i, head, found = 0; 2597 int ret, access; 2598 2599 if (vq->avail_idx == vq->last_avail_idx) { 2600 ret = vhost_get_avail_idx(vq); 2601 if (unlikely(ret)) 2602 return ret; 2603 2604 /* If there's nothing new since last we looked, return 2605 * invalid. 2606 */ 2607 if (vq->avail_idx == vq->last_avail_idx) 2608 return vq->num; 2609 } 2610 2611 /* Grab the next descriptor number they're advertising, and increment 2612 * the index we've seen. */ 2613 head = vhost_get_avail_head(vq); > 2614 if (unlikely(head < 0)) 2615 return head; 2616 2617 /* When we start there are none of either input nor output. */ 2618 *out_num = *in_num = 0; 2619 if (unlikely(log)) 2620 *log_num = 0; 2621 2622 i = head; 2623 do { 2624 unsigned iov_count = *in_num + *out_num; 2625 if (unlikely(i >= vq->num)) { 2626 vq_err(vq, "Desc index is %u > %u, head = %u", 2627 i, vq->num, head); 2628 return -EINVAL; 2629 } 2630 if (unlikely(++found > vq->num)) { 2631 vq_err(vq, "Loop detected: last one at %u " 2632 "vq size %u head %u\n", 2633 i, vq->num, head); 2634 return -EINVAL; 2635 } 2636 ret = vhost_get_desc(vq, &desc, i); 2637 if (unlikely(ret)) { 2638 vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", 2639 i, vq->desc + i); 2640 return -EFAULT; 2641 } 2642 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) { 2643 ret = get_indirect(vq, iov, iov_size, 2644 out_num, in_num, 2645 log, log_num, &desc); 2646 if (unlikely(ret < 0)) { 2647 if (ret != -EAGAIN) 2648 vq_err(vq, "Failure detected " 2649 "in indirect descriptor at idx %d\n", i); 2650 return ret; 2651 } 2652 continue; 2653 } 2654 2655 if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) 2656 access = VHOST_ACCESS_WO; 2657 else 2658 access = VHOST_ACCESS_RO; 2659 ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr), 2660 vhost32_to_cpu(vq, desc.len), iov + iov_count, 2661 iov_size - iov_count, access); 2662 if (unlikely(ret < 0)) { 2663 if (ret != -EAGAIN) 2664 vq_err(vq, "Translation failure %d descriptor idx %d\n", 2665 ret, i); 2666 return ret; 2667 } 2668 if (access == VHOST_ACCESS_WO) { 2669 /* If this is an input descriptor, 2670 * increment that count. */ 2671 *in_num += ret; 2672 if (unlikely(log && ret)) { 2673 log[*log_num].addr = vhost64_to_cpu(vq, desc.addr); 2674 log[*log_num].len = vhost32_to_cpu(vq, desc.len); 2675 ++*log_num; 2676 } 2677 } else { 2678 /* If it's an output descriptor, they're all supposed 2679 * to come before any input descriptors. */ 2680 if (unlikely(*in_num)) { 2681 vq_err(vq, "Descriptor has out after in: " 2682 "idx %d\n", i); 2683 return -EINVAL; 2684 } 2685 *out_num += ret; 2686 } 2687 } while ((i = next_desc(vq, &desc)) != -1); 2688 2689 /* On success, increment avail index. */ 2690 vq->last_avail_idx++; 2691 2692 /* Assume notifications from guest are disabled at this point, 2693 * if they aren't we would need to update avail_event index. */ 2694 BUG_ON(!(vq->used_flags & VRING_USED_F_NO_NOTIFY)); 2695 return head; 2696 } 2697 EXPORT_SYMBOL_GPL(vhost_get_vq_desc); 2698 -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki
