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-...@intel.com/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
| Closes:
https://lore.kernel.org/oe-kbuild-all/202404260448.g7f06v7m-...@intel.com/
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,
2591struct iovec iov[], unsigned int iov_size,
2592unsigned int *out_num, unsigned int *in_num,
2593struct 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, , 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, );
2646 if (unlikely(ret < 0)) {
2647 if (ret != -EAGAIN)
2648 vq_err(vq, "Failure detected "
2649
