Re: [PATCH 1/1] bpf: Fix bpf_event_output re-entry issue

[Daniel Borkmann]

On Wed, Sep 25, 2019 at 04:43:12PM -0700, Allan Zhang wrote:
> BPF_PROG_TYPE_SOCK_OPS program can reenter bpf_event_output because it can
> be called from atomic and non-atomic contexts since we don't have
> bpf_prog_active to prevent it happen.
> 
> This patch enables 3 level of nesting to support normal, irq and nmi
> context.
> 
> We can easily reproduce the issue by running neper crr mode with 100 flows
> and 10 threads from neper client side.
> 
> Here is the whole stack dump:
[...]
> 
> Fixes: a5a3a828cd00 ("bpf: add perf event notificaton support for sock_ops")
> 
> Effort: BPF
> Signed-off-by: Allan Zhang <allanzhang@xxxxxxxxxx>
> Reviewed-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
> Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>

Applied, thanks!