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SubjectRe: [PATCH v2] xsk: share the mmap_sem for page pinning
Den mån 11 feb. 2019 kl 17:15 skrev Davidlohr Bueso <dave@stgolabs.net>:
>
> Holding mmap_sem exclusively for a gup() is an overkill.
> Lets share the lock and replace the gup call for gup_longterm(),
> as it is better suited for the lifetime of the pinning.
>

Thanks for the cleanup!

Acked-by: Björn Töpel <bjorn.topel@intel.com>

> Cc: David S. Miller <davem@davemloft.net>
> Cc: Bjorn Topel <bjorn.topel@intel.com>
> Cc: Magnus Karlsson <magnus.karlsson@intel.com>
> CC: netdev@vger.kernel.org
> Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
> ---
> net/xdp/xdp_umem.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
> index 5ab236c5c9a5..e7fa8d0d7090 100644
> --- a/net/xdp/xdp_umem.c
> +++ b/net/xdp/xdp_umem.c
> @@ -265,10 +265,10 @@ static int xdp_umem_pin_pages(struct xdp_umem *umem)
> if (!umem->pgs)
> return -ENOMEM;
>
> - down_write(&current->mm->mmap_sem);
> - npgs = get_user_pages(umem->address, umem->npgs,
> + down_read(&current->mm->mmap_sem);
> + npgs = get_user_pages_longterm(umem->address, umem->npgs,
> gup_flags, &umem->pgs[0], NULL);
> - up_write(&current->mm->mmap_sem);
> + up_read(&current->mm->mmap_sem);
>
> if (npgs != umem->npgs) {
> if (npgs >= 0) {
> --
> 2.16.4
>

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