> -----Original Message-----
> From: kernel test robot <lkp@intel.com>
> Sent: Wednesday, February 17, 2021 6:21 PM
> To: Lars-Peter Clausen <lars@metafoo.de>
> Cc: kbuild-all(a)lists.01.org; Jonathan Cameron
> <Jonathan.Cameron@huawei.com>; Ardelean, Alexandru
> <alexandru.Ardelean@analog.com>
> Subject: [iio:testing 47/53] drivers/iio/buffer/industrialio-buffer-dma.c:669
> iio_dma_buffer_alloc_blocks() warn: always true condition '(i >= 0) => (0-
> u32max >= 0)'
> 
> [External]
> 
> tree:
> https://urldefense.com/v3/__https://git.kernel.org/pub/scm/linux/kernel/git/jic
> 23/iio.git__;!!A3Ni8CS0y2Y!r0vJx0FTiLi3bS6LugAUkUV4m4kSgQvuRql4XvRJBxLk
> EhqwktjO1ekJmXEVppxQ7ZPMsA$  testing
> head:   0fd146b288591a8139220fec417dfc5652820480
> commit: b9ad66ba4db6f349aa795ed59c3e42d4208844fa [47/53] iio: buffer-
> dma: Add mmap support
> config: x86_64-randconfig-m001-20210215 (attached as .config)
> compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> 
> smatch warnings:
> drivers/iio/buffer/industrialio-buffer-dma.c:669 iio_dma_buffer_alloc_blocks()
> warn: always true condition '(i >= 0) => (0-u32max >= 0)'
> drivers/iio/buffer/industrialio-buffer-dma.c:669 iio_dma_buffer_alloc_blocks()
> warn: always true condition '(i >= 0) => (0-u32max >= 0)'
> 
> vim +669 drivers/iio/buffer/industrialio-buffer-dma.c
> 
>    603
>    604	int iio_dma_buffer_alloc_blocks(struct iio_buffer *buffer,
>    605					struct iio_buffer_block_alloc_req *req)
>    606	{
>    607		struct iio_dma_buffer_queue *queue =
> iio_buffer_to_queue(buffer);
>    608		struct iio_dma_buffer_block **blocks;
>    609		unsigned int num_blocks;
>    610		unsigned int i;
>    611		int ret = 0;
>    612
>    613		mutex_lock(&queue->lock);
>    614
>    615		/*
>    616		 * If the buffer is enabled and in fileio mode new blocks can't be
>    617		 * allocated.
>    618		 */
>    619		if (queue->fileio.enabled) {
>    620			ret = -EBUSY;
>    621			goto err_unlock;
>    622		}
>    623
>    624		/* Free memory that might be in use for fileio mode */
>    625		iio_dma_buffer_fileio_free(queue);
>    626
>    627		/* 64 blocks ought to be enough for anybody ;) */
>    628		if (req->count > 64 - queue->num_blocks)
>    629			req->count = 64 - queue->num_blocks;
>    630		if (req->size > iio_dma_buffer_max_block_size)
>    631			req->size = iio_dma_buffer_max_block_size;
>    632
>    633		req->id = queue->num_blocks;
>    634
>    635		if (req->count == 0 || req->size == 0) {
>    636			ret = 0;
>    637			goto err_unlock;
>    638		}
>    639
>    640		num_blocks = req->count + queue->num_blocks;
>    641
>    642		blocks = krealloc(queue->blocks, sizeof(*blocks) * num_blocks,
>    643				  GFP_KERNEL);
>    644		if (!blocks) {
>    645			ret = -ENOMEM;
>    646			goto err_unlock;
>    647		}
>    648
>    649		for (i = queue->num_blocks; i < num_blocks; i++) {
>    650			blocks[i] = iio_dma_buffer_alloc_block(queue, req-
> >size);
>    651			if (!blocks[i]) {
>    652				ret = -ENOMEM;
>    653				goto err_unwind;
>    654			}
>    655			blocks[i]->block.id = i;
>    656			blocks[i]->block.data.offset = queue->max_offset;
>    657			queue->max_offset += PAGE_ALIGN(req->size);
>    658		}
>    659
>    660		req->count = i - queue->num_blocks;
>    661		queue->num_blocks = i;
>    662		queue->blocks = blocks;
>    663
>    664		mutex_unlock(&queue->lock);
>    665
>    666		return 0;
>    667
>    668	err_unwind:
>  > 669		for (; i >= 0; i--)

Oh crap.
This is actually serious.
Will fix this

>    670			iio_buffer_block_put(blocks[i]);
>    671		kfree(blocks);
>    672	err_unlock:
>    673		mutex_unlock(&queue->lock);
>    674
>    675		return ret;
>    676	}
>    677	EXPORT_SYMBOL_GPL(iio_dma_buffer_alloc_blocks);
>    678
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://urldefense.com/v3/__https://lists.01.org/hyperkitty/list/kbuild-
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> RJBxLkEhqwktjO1ekJmXEVppzqskxNkQ$