netdev - [PATCH net v2 1/2] thunderx: enable page recycling for non-XDP case

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Date:   Tue, 26 Mar 2019 11:53:19 -0400
From:   Dean Nelson <dnelson@...hat.com>
To:     Robert Richter <rric@...nel.org>,
        Sunil Goutham <sgoutham@...ium.com>,
        David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Vadim Lomovtsev <vlomovtsev@...vell.com>
Subject: [PATCH net v2 1/2] thunderx: enable page recycling for non-XDP case

Commit 773225388dae15e72790 ("net: thunderx: Optimize page recycling for XDP")
added code to nicvf_alloc_page() that inadvertently disables receive buffer
page recycling for the non-XDP case by always NULL'ng the page pointer.

This patch corrects two if-conditionals to allow for the recycling of non-XDP
mode pages by only setting the page pointer to NULL when the page is not ready
for recycling.

Fixes: 773225388dae15e72790 ("net: thunderx: Optimize page recycling for XDP")

Signed-off-by: Dean Nelson <dnelson@...hat.com>
---
 drivers/net/ethernet/cavium/thunder/nicvf_queues.c | 23 +++++++++++-----------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
index 5b4d3badcb73..55dbf02c42af 100644
--- a/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
+++ b/drivers/net/ethernet/cavium/thunder/nicvf_queues.c
@@ -105,20 +105,19 @@ static inline struct pgcache *nicvf_alloc_page(struct nicvf *nic,
 	/* Check if page can be recycled */
 	if (page) {
 		ref_count = page_ref_count(page);
-		/* Check if this page has been used once i.e 'put_page'
-		 * called after packet transmission i.e internal ref_count
-		 * and page's ref_count are equal i.e page can be recycled.
+		/* This page can be recycled if internal ref_count and page's
+		 * ref_count are equal, indicating that the page has been used
+		 * once for packet transmission. For non-XDP mode, internal
+		 * ref_count is always '1'.
 		 */
-		if (rbdr->is_xdp && (ref_count == pgcache->ref_count))
-			pgcache->ref_count--;
-		else
-			page = NULL;
-
-		/* In non-XDP mode, page's ref_count needs to be '1' for it
-		 * to be recycled.
-		 */
-		if (!rbdr->is_xdp && (ref_count != 1))
+		if (rbdr->is_xdp) {
+			if (ref_count == pgcache->ref_count)
+				pgcache->ref_count--;
+			else
+				page = NULL;
+		} else if (ref_count != 1) {
 			page = NULL;
+		}
 	}
 
 	if (!page) {