netdev - [PATCH v4 net 10/17] net: Fix a data-race around netdev

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Message-ID: <20220823174700.88411-11-kuniyu@amazon.com>
Date:   Tue, 23 Aug 2022 10:46:53 -0700
From:   Kuniyuki Iwashima <kuniyu@...zon.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>
CC:     Kuniyuki Iwashima <kuniyu@...zon.com>,
        Kuniyuki Iwashima <kuni1840@...il.com>,
        <netdev@...r.kernel.org>, Stephen Hemminger <shemminger@...l.org>
Subject: [PATCH v4 net 10/17] net: Fix a data-race around netdev_budget.

While reading netdev_budget, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.

Fixes: 51b0bdedb8e7 ("[NET]: Separate two usages of netdev_max_backlog.")
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
CC: Stephen Hemminger <shemminger@...l.org>
---
 net/core/dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 4705e6630efa..c83e23cfc57d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6666,7 +6666,7 @@ static __latent_entropy void net_rx_action(struct softirq_action *h)
 	struct softnet_data *sd = this_cpu_ptr(&softnet_data);
 	unsigned long time_limit = jiffies +
 		usecs_to_jiffies(netdev_budget_usecs);
-	int budget = netdev_budget;
+	int budget = READ_ONCE(netdev_budget);
 	LIST_HEAD(list);
 	LIST_HEAD(repoll);
 
-- 
2.30.2