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From: Toshiaki Makita <toshiaki.makita1@gmail.com>
To: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <jakub.kicinski@netronome.com>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	John Fastabend <john.fastabend@gmail.com>
Cc: Toshiaki Makita <toshiaki.makita1@gmail.com>,
	netdev@vger.kernel.org, xdp-newbies@vger.kernel.org,
	bpf@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>, David Ahern <dsahern@gmail.com>
Subject: [PATCH bpf 3/3] devmap: Add missing RCU read lock on flush
Date: Fri, 14 Jun 2019 17:20:15 +0900
Message-ID: <20190614082015.23336-4-toshiaki.makita1@gmail.com> (raw)
In-Reply-To: <20190614082015.23336-1-toshiaki.makita1@gmail.com>

.ndo_xdp_xmit() assumes it is called under RCU. For example virtio_net
uses RCU to detect it has setup the resources for tx. The assumption
accidentally broke when introducing bulk queue in devmap.

Fixes: 5d053f9da431 ("bpf: devmap prepare xdp frames for bulking")
Reported-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Toshiaki Makita <toshiaki.makita1@gmail.com>
---
 kernel/bpf/devmap.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index a126d95..1defea4 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -282,6 +282,7 @@ void __dev_map_flush(struct bpf_map *map)
 	unsigned long *bitmap = this_cpu_ptr(dtab->flush_needed);
 	u32 bit;
 
+	rcu_read_lock();
 	for_each_set_bit(bit, bitmap, map->max_entries) {
 		struct bpf_dtab_netdev *dev = READ_ONCE(dtab->netdev_map[bit]);
 		struct xdp_bulk_queue *bq;
@@ -297,6 +298,7 @@ void __dev_map_flush(struct bpf_map *map)
 
 		__clear_bit(bit, bitmap);
 	}
+	rcu_read_unlock();
 }
 
 /* rcu_read_lock (from syscall and BPF contexts) ensures that if a delete and/or
@@ -389,6 +391,7 @@ static void dev_map_flush_old(struct bpf_dtab_netdev *dev)
 
 		int cpu;
 
+		rcu_read_lock();
 		for_each_online_cpu(cpu) {
 			bitmap = per_cpu_ptr(dev->dtab->flush_needed, cpu);
 			__clear_bit(dev->bit, bitmap);
@@ -396,6 +399,7 @@ static void dev_map_flush_old(struct bpf_dtab_netdev *dev)
 			bq = per_cpu_ptr(dev->bulkq, cpu);
 			bq_xmit_all(dev, bq, XDP_XMIT_FLUSH, false);
 		}
+		rcu_read_unlock();
 	}
 }
 
-- 
1.8.3.1


  parent reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-14  8:20 [PATCH bpf 0/3] Devmap fixes around memory and RCU Toshiaki Makita
2019-06-14  8:20 ` [PATCH bpf 1/3] devmap: Fix premature entry free on destroying map Toshiaki Makita
2019-06-14 11:04   ` Toke Høiland-Jørgensen
2019-06-14 12:10     ` Toke Høiland-Jørgensen
2019-06-14 12:59       ` Toshiaki Makita
2019-06-14 13:09         ` Toke Høiland-Jørgensen
2019-06-14 23:07           ` Daniel Borkmann
2019-06-15 10:10             ` Toke Høiland-Jørgensen
2019-06-14 12:20     ` Jesper Dangaard Brouer
2019-06-14  8:20 ` [PATCH bpf 2/3] devmap: Add missing bulk queue free Toshiaki Makita
2019-06-14 11:58   ` Jesper Dangaard Brouer
2019-06-14 13:03     ` Toshiaki Makita
2019-06-14  8:20 ` Toshiaki Makita [this message]
2019-06-14 11:07   ` [PATCH bpf 3/3] devmap: Add missing RCU read lock on flush Toke Høiland-Jørgensen

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