netdev - [PATCH net] nfp: avoid soft lockups under control message storm

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [day] [month] [year] [list]

Message-Id: <20181002171014.19693-1-jakub.kicinski@netronome.com>
Date:   Tue,  2 Oct 2018 10:10:14 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, oss-drivers@...ronome.com,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: [PATCH net] nfp: avoid soft lockups under control message storm

When FW floods the driver with control messages try to exit the cmsg
processing loop every now and then to avoid soft lockups.  Cmsg
processing is generally very lightweight so 512 seems like a reasonable
budget, which should not be exceeded under normal conditions.

Fixes: 77ece8d5f196 ("nfp: add control vNIC datapath")
Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
Reviewed-by: Simon Horman <simon.horman@...ronome.com>
Tested-by: Pieter Jansen van Vuuren <pieter.jansenvanvuuren@...ronome.com>
---
 .../net/ethernet/netronome/nfp/nfp_net_common.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
index 8ed38fd5a852..c6d29fdbb880 100644
--- a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
+++ b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
@@ -2077,14 +2077,17 @@ nfp_ctrl_rx_one(struct nfp_net *nn, struct nfp_net_dp *dp,
 	return true;
 }
 
-static void nfp_ctrl_rx(struct nfp_net_r_vector *r_vec)
+static bool nfp_ctrl_rx(struct nfp_net_r_vector *r_vec)
 {
 	struct nfp_net_rx_ring *rx_ring = r_vec->rx_ring;
 	struct nfp_net *nn = r_vec->nfp_net;
 	struct nfp_net_dp *dp = &nn->dp;
+	unsigned int budget = 512;
 
-	while (nfp_ctrl_rx_one(nn, dp, r_vec, rx_ring))
+	while (nfp_ctrl_rx_one(nn, dp, r_vec, rx_ring) && budget--)
 		continue;
+
+	return budget;
 }
 
 static void nfp_ctrl_poll(unsigned long arg)
@@ -2096,9 +2099,13 @@ static void nfp_ctrl_poll(unsigned long arg)
 	__nfp_ctrl_tx_queued(r_vec);
 	spin_unlock_bh(&r_vec->lock);
 
-	nfp_ctrl_rx(r_vec);
-
-	nfp_net_irq_unmask(r_vec->nfp_net, r_vec->irq_entry);
+	if (nfp_ctrl_rx(r_vec)) {
+		nfp_net_irq_unmask(r_vec->nfp_net, r_vec->irq_entry);
+	} else {
+		tasklet_schedule(&r_vec->tasklet);
+		nn_dp_warn(&r_vec->nfp_net->dp,
+			   "control message budget exceeded!\n");
+	}
 }
 
 /* Setup and Configuration
-- 
2.17.1