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SubjectRe: [PATCH] PCI/P2PDMA: Save a few cycles in 'pci_alloc_p2pmem()'
[+cc Logan, Eric]

On Wed, Nov 03, 2021 at 10:16:53PM +0100, Christophe JAILLET wrote:
> Use 'percpu_ref_tryget_live_rcu()' instead of 'percpu_ref_tryget_live()' to
> save a few cycles when it is known that the rcu lock is already
> taken/released.
>
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>

Added Logan and Eric since Logan is the author and de facto maintainer
of this file and Eric recently converted this to RCU.

Maybe we need a MAINTAINERS entry for P2PDMA?

> ---
> drivers/pci/p2pdma.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
> index 8d47cb7218d1..081c391690d4 100644
> --- a/drivers/pci/p2pdma.c
> +++ b/drivers/pci/p2pdma.c
> @@ -710,7 +710,7 @@ void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size)
> if (!ret)
> goto out;
>
> - if (unlikely(!percpu_ref_tryget_live(ref))) {
> + if (unlikely(!percpu_ref_tryget_live_rcu(ref))) {
> gen_pool_free(p2pdma->pool, (unsigned long) ret, size);
> ret = NULL;
> goto out;
> --
> 2.30.2
>

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