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bpf, devmap: Add missing RCU read lock on flush

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.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: 5d053f9da4 ("bpf: devmap prepare xdp frames for bulking")
Reported-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Toshiaki Makita <toshiaki.makita1@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Toshiaki Makita 2019-06-14 17:20:15 +09:00 committed by Daniel Borkmann
parent edabf4d9dd
commit 86723c8640
1 changed files with 4 additions and 0 deletions
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4
kernel/bpf/devmap.c
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@ -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();
}
}