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Message-ID: <IA0PR11MB7185AA974CF7207048178187F89E2@IA0PR11MB7185.namprd11.prod.outlook.com>
Date: Fri, 6 Sep 2024 08:17:36 +0000
From: "Kasireddy, Vivek" <vivek.kasireddy@...el.com>
To: Huan Yang <link@...o.com>, Sumit Semwal <sumit.semwal@...aro.org>,
Christian König <christian.koenig@....com>, Gerd Hoffmann
<kraxel@...hat.com>, "linux-media@...r.kernel.org"
<linux-media@...r.kernel.org>, "dri-devel@...ts.freedesktop.org"
<dri-devel@...ts.freedesktop.org>, "linaro-mm-sig@...ts.linaro.org"
<linaro-mm-sig@...ts.linaro.org>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>
CC: "opensource.kernel@...o.com" <opensource.kernel@...o.com>
Subject: RE: [PATCH v5 4/7] udmabuf: udmabuf_create pin folio codestyle
cleanup
Hi Huan,
> Subject: [PATCH v5 4/7] udmabuf: udmabuf_create pin folio codestyle
> cleanup
>
> This patch split pin folios into single function: udmabuf_pin_folios.
>
> When record folio and offset into udmabuf_folio and offsets, the outer
> loop of this patch iterates through folios, while the inner loop correctly
> sets the folio and corresponding offset into the udmabuf starting from
> the offset. if reach to pgcnt or nr_folios, end of loop.
>
> By this, more readable.
>
> Signed-off-by: Huan Yang <link@...o.com>
> ---
> drivers/dma-buf/udmabuf.c | 132 ++++++++++++++++++++------------------
> 1 file changed, 71 insertions(+), 61 deletions(-)
>
> diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
> index 456db58446e1..ca2b21c5c57f 100644
> --- a/drivers/dma-buf/udmabuf.c
> +++ b/drivers/dma-buf/udmabuf.c
> @@ -330,17 +330,67 @@ static int export_udmabuf(struct udmabuf *ubuf,
> return dma_buf_fd(buf, flags);
> }
>
> +static int udmabuf_pin_folios(struct udmabuf *ubuf, struct file *memfd,
> + loff_t start, loff_t size)
> +{
> + pgoff_t pgoff, pgcnt, upgcnt = ubuf->pagecount;
> + u32 cur_folio, cur_pgcnt;
> + struct folio **folios = NULL;
> + long nr_folios;
> + loff_t end;
> + int ret = 0;
Change ret's type and this function's return type to long for consistency.
> +
> + 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 err;
> + }
> +
> + 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 err;
> +
> + for (; subpgoff < fsize; subpgoff += PAGE_SIZE) {
> + ubuf->folios[upgcnt] = folios[cur_folio];
> + ubuf->offsets[upgcnt] = subpgoff;
> + ++upgcnt;
> +
> + if (++cur_pgcnt >= pgcnt)
> + goto end;
> + }
> +
> + /**
> + * The term range may start with offset, so the first folio
> + * need take care of it. And the remain folio start from 0.
The comments above are not very meaningful. Please rewrite them as:
* 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:
> +err:
No need to have two labels here. Keep end and get rid of err?
> + 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;
> + long ret = -EINVAL;
> struct udmabuf *ubuf;
> - u32 i, j, k, flags;
> - loff_t end;
> + u32 i, flags;
>
> ubuf = kzalloc(sizeof(*ubuf), GFP_KERNEL);
> if (!ubuf)
> @@ -349,81 +399,43 @@ 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);
> + struct file *memfd = fget(list[i].memfd);
> +
> ret = check_memfd_seals(memfd);
> if (ret < 0)
> goto err;
>
> - pgcnt = list[i].size >> PAGE_SHIFT;
> - folios = kvmalloc_array(pgcnt, sizeof(*folios), GFP_KERNEL);
> - if (!folios) {
> - ret = -ENOMEM;
> - 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;
> - 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;
> @@ -434,8 +446,6 @@ static long udmabuf_create(struct miscdevice
> *device,
> return ret;
>
> err:
> - if (memfd)
> - fput(memfd);
I think this needs to stay because if the seals check fails, then we would not be
doing fput(memfd).
Thanks,
Vivek
> unpin_all_folios(&ubuf->unpin_list);
> kvfree(ubuf->offsets);
> kvfree(ubuf->folios);
> --
> 2.45.2
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