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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
        Shwetha Nagaraju <shwetha.nagaraju@intel.com>,
        Tony Nguyen <anthony.l.nguyen@intel.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 117/171] ice: synchronize_rcu() when terminating rings
Date:   Tue, 12 Apr 2022 08:30:08 +0200
Message-Id: <20220412062931.271224763@linuxfoundation.org>
In-Reply-To: <20220412062927.870347203@linuxfoundation.org>
References: <20220412062927.870347203@linuxfoundation.org>
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From: Maciej Fijalkowski <maciej.fijalkowski@intel.com>

[ Upstream commit f9124c68f05ffdb87a47e3ea6d5fae9dad7cb6eb ]

Unfortunately, the ice driver doesn't respect the RCU critical section that
XSK wakeup is surrounded with. To fix this, add synchronize_rcu() calls to
paths that destroy resources that might be in use.

This was addressed in other AF_XDP ZC enabled drivers, for reference see
for example commit b3873a5be757 ("net/i40e: Fix concurrency issues
between config flow and XSK")

Fixes: efc2214b6047 ("ice: Add support for XDP")
Fixes: 2d4238f55697 ("ice: Add support for AF_XDP")
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Tested-by: Shwetha Nagaraju <shwetha.nagaraju@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/intel/ice/ice.h      | 2 +-
 drivers/net/ethernet/intel/ice/ice_main.c | 4 +++-
 drivers/net/ethernet/intel/ice/ice_xsk.c  | 4 +++-
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice.h b/drivers/net/ethernet/intel/ice/ice.h
index 6a57b41ddb54..7794703c1359 100644
--- a/drivers/net/ethernet/intel/ice/ice.h
+++ b/drivers/net/ethernet/intel/ice/ice.h
@@ -498,7 +498,7 @@ static inline struct ice_pf *ice_netdev_to_pf(struct net_device *netdev)
 
 static inline bool ice_is_xdp_ena_vsi(struct ice_vsi *vsi)
 {
-	return !!vsi->xdp_prog;
+	return !!READ_ONCE(vsi->xdp_prog);
 }
 
 static inline void ice_set_ring_xdp(struct ice_ring *ring)
diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
index 20c9d55f3adc..eb0625b52e45 100644
--- a/drivers/net/ethernet/intel/ice/ice_main.c
+++ b/drivers/net/ethernet/intel/ice/ice_main.c
@@ -2475,8 +2475,10 @@ int ice_destroy_xdp_rings(struct ice_vsi *vsi)
 
 	for (i = 0; i < vsi->num_xdp_txq; i++)
 		if (vsi->xdp_rings[i]) {
-			if (vsi->xdp_rings[i]->desc)
+			if (vsi->xdp_rings[i]->desc) {
+				synchronize_rcu();
 				ice_free_tx_ring(vsi->xdp_rings[i]);
+			}
 			kfree_rcu(vsi->xdp_rings[i], rcu);
 			vsi->xdp_rings[i] = NULL;
 		}
diff --git a/drivers/net/ethernet/intel/ice/ice_xsk.c b/drivers/net/ethernet/intel/ice/ice_xsk.c
index 9f36f8d7a985..5733526fa245 100644
--- a/drivers/net/ethernet/intel/ice/ice_xsk.c
+++ b/drivers/net/ethernet/intel/ice/ice_xsk.c
@@ -36,8 +36,10 @@ static void ice_qp_reset_stats(struct ice_vsi *vsi, u16 q_idx)
 static void ice_qp_clean_rings(struct ice_vsi *vsi, u16 q_idx)
 {
 	ice_clean_tx_ring(vsi->tx_rings[q_idx]);
-	if (ice_is_xdp_ena_vsi(vsi))
+	if (ice_is_xdp_ena_vsi(vsi)) {
+		synchronize_rcu();
 		ice_clean_tx_ring(vsi->xdp_rings[q_idx]);
+	}
 	ice_clean_rx_ring(vsi->rx_rings[q_idx]);
 }
 
-- 
2.35.1