Hi Huan,
> Subject: Re: [PATCH v5 4/7] udmabuf: udmabuf_create pin folio codestyle
> cleanup
>
>
> 在 2024/9/6 16:17, Kasireddy, Vivek 写道:
> > 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@xxxxxxxx>
> >> ---
> >> 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).
>
> Yes, there a mistake, but I'd like set it into here:
>
> ret = check_memfd_seals(memfd);
> if (ret < 0) {
You still need an if (memfd) check here because check_memfd_seals() might do:
if (!memfd)
return -EBADFD;
Thanks,
Vivek
> fput(memfd);
> goto err;
> }
> due to only in inner look, memfd can get. and memfd change into loop var.
> Thanks
>
> >
> > Thanks,
> > Vivek
> >
> >> unpin_all_folios(&ubuf->unpin_list);
> >> kvfree(ubuf->offsets);
> >> kvfree(ubuf->folios);
> >> --
> >> 2.45.2
