RE: [PATCH v6 4/7] udmabuf: udmabuf_create pin folio codestyle cleanup

[Kasireddy, Vivek]

Hi Huan,

> Subject: [PATCH v6 4/7] udmabuf: udmabuf_create pin folio codestyle
> cleanup
> 
> This patch aims to simplify the pinning of folio during the udmabuf
> creation. No functional changes.
> 
> This patch moves the memfd pin folio to udmabuf_pin_folios and modifies
> the original loop condition, using the pinned folio as the external
> loop condition, and sets the offset and folio during the traversal process.
> 
> By this, more readable.
> 
> Suggested-by: Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx>
> Signed-off-by: Huan Yang <link@xxxxxxxx>
> ---
>  drivers/dma-buf/udmabuf.c | 134 +++++++++++++++++++++-----------------
>  1 file changed, 76 insertions(+), 58 deletions(-)
> 
> diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
> index aa182a9dcdfa..fe1466f7d55a 100644
> --- a/drivers/dma-buf/udmabuf.c
> +++ b/drivers/dma-buf/udmabuf.c
> @@ -328,17 +328,68 @@ static int export_udmabuf(struct udmabuf *ubuf,
>  	return dma_buf_fd(buf, flags);
>  }
> 
> +static long udmabuf_pin_folios(struct udmabuf *ubuf, struct file *memfd,
> +			       loff_t start, loff_t size)
> +{
> +	pgoff_t pgoff, pgcnt, upgcnt = ubuf->pagecount;
> +	struct folio **folios = NULL;
> +	u32 cur_folio, cur_pgcnt;
> +	long nr_folios;
> +	long ret = 0;
> +	loff_t end;
> +
> +	pgcnt = size >> PAGE_SHIFT;
> +	folios = kvmalloc_array(pgcnt, sizeof(*folios), GFP_KERNEL);
> +	if (!folios)
> +		return -ENOMEM;
> +
> +	end = start + (pgcnt << PAGE_SHIFT) - 1;
> +	nr_folios = memfd_pin_folios(memfd, start, end, folios, pgcnt,
> &pgoff);
> +	if (nr_folios <= 0) {
> +		ret = nr_folios ? nr_folios : -EINVAL;
> +		goto end;
> +	}
> +
> +	cur_pgcnt = 0;
> +	for (cur_folio = 0; cur_folio < nr_folios; ++cur_folio) {
> +		pgoff_t subpgoff = pgoff;
> +		size_t fsize = folio_size(folios[cur_folio]);
> +
> +		ret = add_to_unpin_list(&ubuf->unpin_list, folios[cur_folio]);
> +		if (ret < 0)
> +			goto end;
> +
> +		for (; subpgoff < fsize; subpgoff += PAGE_SIZE) {
> +			ubuf->folios[upgcnt] = folios[cur_folio];
> +			ubuf->offsets[upgcnt] = subpgoff;
> +			++upgcnt;
> +
> +			if (++cur_pgcnt >= pgcnt)
> +				goto end;
> +		}
> +
> +		/**
> +		 * In a given range, only the first subpage of the first folio
> +		 * has an offset, that is returned by memfd_pin_folios().
> +		 * The first subpages of other folios (in the range) have an
> +		 * offset of 0.
> +		 */
> +		pgoff = 0;
> +	}
> +end:
> +	ubuf->pagecount = upgcnt;
> +	kvfree(folios);
> +	return ret;
> +}
> +
>  static long udmabuf_create(struct miscdevice *device,
>  			   struct udmabuf_create_list *head,
>  			   struct udmabuf_create_item *list)
>  {
> -	pgoff_t pgoff, pgcnt, pglimit, pgbuf = 0;
> -	long nr_folios, ret = -EINVAL;
> -	struct file *memfd = NULL;
> -	struct folio **folios;
> +	pgoff_t pgcnt = 0, pglimit;
>  	struct udmabuf *ubuf;
> -	u32 i, j, k, flags;
> -	loff_t end;
> +	long ret = -EINVAL;
> +	u32 i, flags;
> 
>  	ubuf = kzalloc(sizeof(*ubuf), GFP_KERNEL);
>  	if (!ubuf)
> @@ -347,81 +398,50 @@ static long udmabuf_create(struct miscdevice
> *device,
>  	INIT_LIST_HEAD(&ubuf->unpin_list);
>  	pglimit = (size_limit_mb * 1024 * 1024) >> PAGE_SHIFT;
>  	for (i = 0; i < head->count; i++) {
> -		if (!IS_ALIGNED(list[i].offset, PAGE_SIZE))
> +		if (!PAGE_ALIGNED(list[i].offset))
>  			goto err;
> -		if (!IS_ALIGNED(list[i].size, PAGE_SIZE))
> +		if (!PAGE_ALIGNED(list[i].size))
>  			goto err;
> -		ubuf->pagecount += list[i].size >> PAGE_SHIFT;
> -		if (ubuf->pagecount > pglimit)
> +
> +		pgcnt += list[i].size >> PAGE_SHIFT;
> +		if (pgcnt > pglimit)
>  			goto err;
>  	}
> 
> -	if (!ubuf->pagecount)
> +	if (!pgcnt)
>  		goto err;
> 
> -	ubuf->folios = kvmalloc_array(ubuf->pagecount, sizeof(*ubuf-
> >folios),
> -				      GFP_KERNEL);
> +	ubuf->folios = kvmalloc_array(pgcnt, sizeof(*ubuf->folios),
> GFP_KERNEL);
>  	if (!ubuf->folios) {
>  		ret = -ENOMEM;
>  		goto err;
>  	}
> -	ubuf->offsets = kvcalloc(ubuf->pagecount, sizeof(*ubuf->offsets),
> -				 GFP_KERNEL);
> +
> +	ubuf->offsets = kvcalloc(pgcnt, sizeof(*ubuf->offsets), GFP_KERNEL);
>  	if (!ubuf->offsets) {
>  		ret = -ENOMEM;
>  		goto err;
>  	}
> 
> -	pgbuf = 0;
>  	for (i = 0; i < head->count; i++) {
> -		memfd = fget(list[i].memfd);
> -		ret = check_memfd_seals(memfd);
> -		if (ret < 0)
> -			goto err;
> +		struct file *memfd = fget(list[i].memfd);
> 
> -		pgcnt = list[i].size >> PAGE_SHIFT;
> -		folios = kvmalloc_array(pgcnt, sizeof(*folios), GFP_KERNEL);
> -		if (!folios) {
> -			ret = -ENOMEM;
> +		if (!memfd) {
> +			ret = -EBADFD;
Nit: with the above change added, please remove the redundant if (!memfd)
check from check_memfd_seals().

Acked-by: Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx>

>  			goto err;
>  		}
> 
> -		end = list[i].offset + (pgcnt << PAGE_SHIFT) - 1;
> -		ret = memfd_pin_folios(memfd, list[i].offset, end,
> -				       folios, pgcnt, &pgoff);
> -		if (ret <= 0) {
> -			kvfree(folios);
> -			if (!ret)
> -				ret = -EINVAL;
> +		ret = check_memfd_seals(memfd);
> +		if (ret < 0) {
> +			fput(memfd);
>  			goto err;
>  		}
> 
> -		nr_folios = ret;
> -		pgoff >>= PAGE_SHIFT;
> -		for (j = 0, k = 0; j < pgcnt; j++) {
> -			ubuf->folios[pgbuf] = folios[k];
> -			ubuf->offsets[pgbuf] = pgoff << PAGE_SHIFT;
> -
> -			if (j == 0 || ubuf->folios[pgbuf-1] != folios[k]) {
> -				ret = add_to_unpin_list(&ubuf->unpin_list,
> -							folios[k]);
> -				if (ret < 0) {
> -					kfree(folios);
> -					goto err;
> -				}
> -			}
> -
> -			pgbuf++;
> -			if (++pgoff == folio_nr_pages(folios[k])) {
> -				pgoff = 0;
> -				if (++k == nr_folios)
> -					break;
> -			}
> -		}
> -
> -		kvfree(folios);
> +		ret = udmabuf_pin_folios(ubuf, memfd, list[i].offset,
> +					 list[i].size);
>  		fput(memfd);
> -		memfd = NULL;
> +		if (ret)
> +			goto err;
>  	}
> 
>  	flags = head->flags & UDMABUF_FLAGS_CLOEXEC ? O_CLOEXEC : 0;
> @@ -432,8 +452,6 @@ static long udmabuf_create(struct miscdevice
> *device,
>  	return ret;
> 
>  err:
> -	if (memfd)
> -		fput(memfd);
>  	unpin_all_folios(&ubuf->unpin_list);
>  	kvfree(ubuf->offsets);
>  	kvfree(ubuf->folios);
> --
> 2.45.2