netdev - Re: [PATCH v2 bpf-next 2/4] bpf: allow bpf_d_path in sleepable bpf

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Date:   Mon, 25 Jan 2021 13:52:13 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Song Liu <songliubraving@...com>
Cc:     bpf@...r.kernel.org, netdev@...r.kernel.org, ast@...nel.org,
        daniel@...earbox.net, andrii@...nel.org, john.fastabend@...il.com,
        kpsingh@...omium.org, kernel-team@...com
Subject: Re: [PATCH v2 bpf-next 2/4] bpf: allow bpf_d_path in sleepable
 bpf_iter program

On Tue, Dec 15, 2020 at 03:37:00PM -0800, Song Liu wrote:
> task_file and task_vma iter programs have access to file->f_path. Enable
> bpf_d_path to print paths of these file.
> 
> bpf_iter programs are generally called in sleepable context. However, it
> is still necessary to diffientiate sleepable and non-sleepable bpf_iter
> programs: sleepable programs have access to bpf_d_path; non-sleepable
> programs have access to bpf_spin_lock.
> 
> Signed-off-by: Song Liu <songliubraving@...com>
> ---
>  kernel/trace/bpf_trace.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 4be771df5549a..9e5f9b968355f 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -1191,6 +1191,11 @@ BTF_SET_END(btf_allowlist_d_path)
>  
>  static bool bpf_d_path_allowed(const struct bpf_prog *prog)
>  {
> +	if (prog->type == BPF_PROG_TYPE_TRACING &&
> +	    prog->expected_attach_type == BPF_TRACE_ITER &&
> +	    prog->aux->sleepable)
> +		return true;
> +
>  	if (prog->type == BPF_PROG_TYPE_LSM)
>  		return bpf_lsm_is_sleepable_hook(prog->aux->attach_btf_id);
>  
> -- 
> 2.24.1
> 

would be great to have this merged for bpftrace

Tested-by: Jiri Olsa <jolsa@...hat.com>

thanks,
jirka