Commit 4005f5c3 authored May 06, 2020 by Jason A. Donenfeld Committed by David S. Miller May 06, 2020

wireguard: send/receive: cond_resched() when processing worker ringbuffers



Users with pathological hardware reported CPU stalls on CONFIG_
PREEMPT_VOLUNTARY=y, because the ringbuffers would stay full, meaning
these workers would never terminate. That turned out not to be okay on
systems without forced preemption, which Sultan observed. This commit
adds a cond_resched() to the bottom of each loop iteration, so that
these workers don't hog the core. Note that we don't need this on the
napi poll worker, since that terminates after its budget is expended.

Suggested-by: Sultan Alsawaf <sultan@kerneltoast.com>
Reported-by: Wang Jian <larkwang@gmail.com>
Fixes: e7096c13 ("net: WireGuard secure network tunnel")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent b673e24a

drivers/net/wireguard/receive.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -516,6 +516,8 @@ void wg_packet_decrypt_worker(struct work_struct *work)
		&PACKET_CB(skb)->keypair->receiving)) ?
		PACKET_STATE_CRYPTED : PACKET_STATE_DEAD;
		wg_queue_enqueue_per_peer_napi(skb, state);
		if (need_resched())
		cond_resched();
		}
		}

drivers/net/wireguard/send.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -281,6 +281,8 @@ void wg_packet_tx_worker(struct work_struct *work)

		wg_noise_keypair_put(keypair, false);
		wg_peer_put(peer);
		if (need_resched())
		cond_resched();
		}
		}

		@@ -304,6 +306,8 @@ void wg_packet_encrypt_worker(struct work_struct *work)
		}
		wg_queue_enqueue_per_peer(&PACKET_PEER(first)->tx_queue, first,
		state);
		if (need_resched())
		cond_resched();
		}
		}

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