Re: [PATCH v4 1/2] virtio_blk: Add control virtqueue support

[kernel test robot <lkp@intel.com>]

Hi Linlin,

kernel test robot noticed the following build warnings:

[auto build test WARNING on axboe/for-next]
[also build test WARNING on mst-vhost/linux-next linus/master v7.3-rc6 next-20261008]
[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/Linlin-Zhang/virtio_blk-Add-control-virtqueue-support/20261008-211713
base:   https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux.git for-next
patch link:    https://lore.kernel.org/r/20261009041727.3170811-2-linlin.zhang%40oss.qualcomm.com
patch subject: [PATCH v4 1/2] virtio_blk: Add control virtqueue support
config: x86_64-defconfig (https://download.01.org/0day-ci/archive/20261010/202610100905.au1oY0vX-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20261010/202610100905.au1oY0vX-lkp@intel.com/reproduce)

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@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202610100905.au1oY0vX-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/block/virtio_blk.c:1000:12: warning: 'virtblk_ctrl_vq_request' defined but not used [-Wunused-function]
    1000 | static int virtblk_ctrl_vq_request(struct virtio_blk *vblk,
         |            ^~~~~~~~~~~~~~~~~~~~~~~


vim +/virtblk_ctrl_vq_request +1000 drivers/block/virtio_blk.c

   998	
   999	/* Submit a control-queue request and wait for completion. */
> 1000	static int virtblk_ctrl_vq_request(struct virtio_blk *vblk,
  1001					    struct virtblk_ctrl_request *creq,
  1002					    struct scatterlist *sgs[],
  1003					    unsigned int out_sgs, unsigned int in_sgs)
  1004	{
  1005		struct virtblk_ctrl_completion *comp;
  1006		unsigned long flags;
  1007		int err;
  1008	
  1009		/*
  1010		 * GFP_NOIO: this may be reached on the bio-submission path
  1011		 * (memory reclaim writing back dirty pages to this same device),
  1012		 * so GFP_KERNEL could self-deadlock.
  1013		 */
  1014		comp = kmalloc_obj(*comp, GFP_NOIO);
  1015		if (!comp)
  1016			return -ENOMEM;
  1017		init_completion(&comp->done);
  1018		comp->abandoned = false;
  1019	
  1020		mutex_lock(&vblk->ctrl_vq.mutex);
  1021		creq->compl = comp;
  1022	
  1023		spin_lock_irqsave(&vblk->ctrl_vq.lock, flags);
  1024		if (vblk->ctrl_vq.dead) {
  1025			spin_unlock_irqrestore(&vblk->ctrl_vq.lock, flags);
  1026			mutex_unlock(&vblk->ctrl_vq.mutex);
  1027			kfree(comp);
  1028			creq->compl = NULL;
  1029			return -ENODEV;
  1030		}
  1031		err = virtqueue_add_sgs(vblk->ctrl_vq.vq, sgs, out_sgs, in_sgs, creq, GFP_ATOMIC);
  1032		if (!err) {
  1033			vblk->ctrl_vq.inflight++;
  1034			virtqueue_kick(vblk->ctrl_vq.vq);
  1035		}
  1036		spin_unlock_irqrestore(&vblk->ctrl_vq.lock, flags);
  1037		if (err) {
  1038			mutex_unlock(&vblk->ctrl_vq.mutex);
  1039			kfree(comp);
  1040			creq->compl = NULL;
  1041			return err;
  1042		}
  1043	
  1044		if (wait_for_completion_timeout(&comp->done, VIRTBLK_CTRL_VQ_TIMEOUT)) {
  1045			mutex_unlock(&vblk->ctrl_vq.mutex);
  1046			kfree(comp);
  1047			creq->compl = NULL;
  1048			return 0;
  1049		}
  1050	
  1051		/*
  1052		 * The host hasn't responded within the timeout. @creq is still
  1053		 * owned by the device, so don't touch its DMA-target fields or
  1054		 * free it here. Mark it abandoned and hand ownership of both @creq
  1055		 * and @comp to whichever of virtblk_ctrlq_callback() or
  1056		 * virtblk_ctrl_vq_drain() retrieves the buffer later; unlock the
  1057		 * mutex so subsequent requests aren't serialized behind an
  1058		 * unresponsive host.
  1059		 */
  1060		spin_lock_irqsave(&vblk->ctrl_vq.lock, flags);
  1061		comp->abandoned = true;
  1062		spin_unlock_irqrestore(&vblk->ctrl_vq.lock, flags);
  1063		mutex_unlock(&vblk->ctrl_vq.mutex);
  1064	
  1065		dev_warn(&vblk->vdev->dev,
  1066			 "control queue request timed out, abandoning\n");
  1067		return -ETIMEDOUT;
  1068	}
  1069	

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