netdev - RE: [PATCH bpf 3/3] selftests/bpf: Test freeing sockmap/sockhash with a socket in it

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Date:   Thu, 06 Feb 2020 11:03:13 -0800
From:   John Fastabend <john.fastabend@...il.com>
To:     Jakub Sitnicki <jakub@...udflare.com>, bpf@...r.kernel.org
Cc:     netdev@...r.kernel.org, kernel-team@...udflare.com,
        John Fastabend <john.fastabend@...il.com>
Subject: RE: [PATCH bpf 3/3] selftests/bpf: Test freeing sockmap/sockhash with
 a socket in it

Jakub Sitnicki wrote:
> Commit 7e81a3530206 ("bpf: Sockmap, ensure sock lock held during tear
> down") introduced sleeping issues inside RCU critical sections and while
> holding a spinlock on sockmap/sockhash tear-down. There has to be at least
> one socket in the map for the problem to surface.
> 
> This adds a test that triggers the warnings for broken locking rules. Not a
> fix per se, but rather tooling to verify the accompanying fixes. Run on a
> VM with 1 vCPU to reproduce the warnings.
> 
> Fixes: 7e81a3530206 ("bpf: Sockmap, ensure sock lock held during tear down")
> Signed-off-by: Jakub Sitnicki <jakub@...udflare.com>
> ---
>  .../selftests/bpf/prog_tests/sockmap_basic.c  | 74 +++++++++++++++++++
>  1 file changed, 74 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> new file mode 100644
> index 000000000000..07f5b462c2ef
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c

Yes! This helps a lot now we will get some coverege on these cases.

Acked-by: John Fastabend <john.fastabend@...il.com>