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SubjectRe: [PATCH v2] tee: convert get_user_pages() --> pin_user_pages()
Hi John,

On Tue, May 26, 2020 at 1:32 AM John Hubbard <jhubbard@nvidia.com> wrote:
>
> This code was using get_user_pages*(), in a "Case 2" scenario
> (DMA/RDMA), using the categorization from [1]. That means that it's
> time to convert the get_user_pages*() + put_page() calls to
> pin_user_pages*() + unpin_user_pages() calls.
>
> There is some helpful background in [2]: basically, this is a small
> part of fixing a long-standing disconnect between pinning pages, and
> file systems' use of those pages.
>
> [1] Documentation/core-api/pin_user_pages.rst
>
> [2] "Explicit pinning of user-space pages":
> https://lwn.net/Articles/807108/
>
> Cc: Jens Wiklander <jens.wiklander@linaro.org>
> Cc: Sumit Semwal <sumit.semwal@linaro.org>
> Cc: tee-dev@lists.linaro.org
> Cc: linux-media@vger.kernel.org
> Cc: dri-devel@lists.freedesktop.org
> Cc: linaro-mm-sig@lists.linaro.org
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
> ---
>
> Hi,
>
> This fixes the typo ("convert convert") in the subject line, but
> otherwise no changes.
>
> thanks,
> John Hubbard
> NVIDIA
>
>
> drivers/tee/tee_shm.c | 12 +++---------
> 1 file changed, 3 insertions(+), 9 deletions(-)

Looks good. I've tested this on a HiKey 620 board, no regressions. I'm
picking up this patch.

Thanks,
Jens

>
> diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> index bd679b72bd05..7dffc42d8d5a 100644
> --- a/drivers/tee/tee_shm.c
> +++ b/drivers/tee/tee_shm.c
> @@ -31,16 +31,13 @@ static void tee_shm_release(struct tee_shm *shm)
>
> poolm->ops->free(poolm, shm);
> } else if (shm->flags & TEE_SHM_REGISTER) {
> - size_t n;
> int rc = teedev->desc->ops->shm_unregister(shm->ctx, shm);
>
> if (rc)
> dev_err(teedev->dev.parent,
> "unregister shm %p failed: %d", shm, rc);
>
> - for (n = 0; n < shm->num_pages; n++)
> - put_page(shm->pages[n]);
> -
> + unpin_user_pages(shm->pages, shm->num_pages);
> kfree(shm->pages);
> }
>
> @@ -226,7 +223,7 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
> goto err;
> }
>
> - rc = get_user_pages_fast(start, num_pages, FOLL_WRITE, shm->pages);
> + rc = pin_user_pages_fast(start, num_pages, FOLL_WRITE, shm->pages);
> if (rc > 0)
> shm->num_pages = rc;
> if (rc != num_pages) {
> @@ -271,16 +268,13 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
> return shm;
> err:
> if (shm) {
> - size_t n;
> -
> if (shm->id >= 0) {
> mutex_lock(&teedev->mutex);
> idr_remove(&teedev->idr, shm->id);
> mutex_unlock(&teedev->mutex);
> }
> if (shm->pages) {
> - for (n = 0; n < shm->num_pages; n++)
> - put_page(shm->pages[n]);
> + unpin_user_pages(shm->pages, shm->num_pages);
> kfree(shm->pages);
> }
> }
> --
> 2.26.2
>

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