From: Daniel Borkmann <daniel@iogearbox.net>
To: Alexei Starovoitov <ast@fb.com>,
"David S . Miller" <davem@davemloft.net>
Cc: Daniel Wagner <daniel.wagner@bmw-carit.de>,
Tom Zanussi <tom.zanussi@linux.intel.com>,
Wang Nan <wangnan0@huawei.com>, He Kuang <hekuang@huawei.com>,
Martin KaFai Lau <kafai@fb.com>,
Brendan Gregg <brendan.d.gregg@gmail.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com
Subject: Re: [PATCH net-next 1/9] bpf: prevent kprobe+bpf deadlocks
Date: Mon, 07 Mar 2016 11:07:44 +0100 [thread overview]
Message-ID: <56DD52F0.1060604@iogearbox.net> (raw)
In-Reply-To: <1457315917-1970307-2-git-send-email-ast@fb.com>
On 03/07/2016 02:58 AM, Alexei Starovoitov wrote:
> if kprobe is placed within update or delete hash map helpers
> that hold bucket spin lock and triggered bpf program is trying to
> grab the spinlock for the same bucket on the same cpu, it will
> deadlock.
> Fix it by extending existing recursion prevention mechanism.
>
> Note, map_lookup and other tracing helpers don't have this problem,
> since they don't hold any locks and don't modify global data.
> bpf_trace_printk has its own recursive check and ok as well.
>
> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
LGTM
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
next prev parent reply other threads:[~2016-03-07 10:08 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-07 1:58 [PATCH net-next 0/9] bpf: hash map pre-alloc Alexei Starovoitov
2016-03-07 1:58 ` [PATCH net-next 1/9] bpf: prevent kprobe+bpf deadlocks Alexei Starovoitov
2016-03-07 10:07 ` Daniel Borkmann [this message]
2016-03-07 1:58 ` [PATCH net-next 2/9] bpf: introduce percpu_freelist Alexei Starovoitov
2016-03-07 10:33 ` Daniel Borkmann
2016-03-07 18:26 ` Alexei Starovoitov
2016-03-07 1:58 ` [PATCH net-next 3/9] bpf: pre-allocate hash map elements Alexei Starovoitov
2016-03-07 11:08 ` Daniel Borkmann
2016-03-07 18:29 ` Alexei Starovoitov
2016-03-07 1:58 ` [PATCH net-next 4/9] samples/bpf: make map creation more verbose Alexei Starovoitov
2016-03-07 1:58 ` [PATCH net-next 5/9] samples/bpf: move ksym_search() into library Alexei Starovoitov
2016-03-07 1:58 ` [PATCH net-next 6/9] samples/bpf: add map_flags to bpf loader Alexei Starovoitov
2016-03-07 1:58 ` [PATCH net-next 7/9] samples/bpf: test both pre-alloc and normal maps Alexei Starovoitov
2016-03-07 1:58 ` [PATCH net-next 8/9] samples/bpf: add bpf map stress test Alexei Starovoitov
2016-03-07 1:58 ` [PATCH net-next 9/9] samples/bpf: add map performance test Alexei Starovoitov
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