linux-kernel - [PATCH bpf v5 1/2] xdp: hold device for umem regardless of zero-copy mode

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Message-Id: <20190627101529.11234-2-i.maximets@samsung.com>
Date:   Thu, 27 Jun 2019 13:15:28 +0300
From:   Ilya Maximets <i.maximets@...sung.com>
To:     netdev@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
        xdp-newbies@...r.kernel.org,
        "David S. Miller" <davem@...emloft.net>,
        Björn Töpel <bjorn.topel@...el.com>,
        Magnus Karlsson <magnus.karlsson@...el.com>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Ilya Maximets <i.maximets@...sung.com>
Subject: [PATCH bpf v5 1/2] xdp: hold device for umem regardless of
 zero-copy mode

Device pointer stored in umem regardless of zero-copy mode,
so we heed to hold the device in all cases.

Fixes: c9b47cc1fabc ("xsk: fix bug when trying to use both copy and zero-copy on one queue id")
Signed-off-by: Ilya Maximets <i.maximets@...sung.com>
---
 net/xdp/xdp_umem.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index 9c6de4f114f8..267b82a4cbcf 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -105,6 +105,9 @@ int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev,
 
 	umem->dev = dev;
 	umem->queue_id = queue_id;
+
+	dev_hold(dev);
+
 	if (force_copy)
 		/* For copy-mode, we are done. */
 		goto out_rtnl_unlock;
@@ -124,7 +127,6 @@ int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev,
 		goto err_unreg_umem;
 	rtnl_unlock();
 
-	dev_hold(dev);
 	umem->zc = true;
 	return 0;
 
@@ -163,10 +165,9 @@ static void xdp_umem_clear_dev(struct xdp_umem *umem)
 	xdp_clear_umem_at_qid(umem->dev, umem->queue_id);
 	rtnl_unlock();
 
-	if (umem->zc) {
-		dev_put(umem->dev);
-		umem->zc = false;
-	}
+	dev_put(umem->dev);
+	umem->dev = NULL;
+	umem->zc = false;
 }
 
 static void xdp_umem_unpin_pages(struct xdp_umem *umem)
-- 
2.17.1