Date: Wed, 10 Jan 2018 10:21:39 -0500
From: Josef Bacik <josef@toxicpanda.com>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexei Starovoitov <ast@fb.com>, Josef Bacik <jbacik@fb.com>,
        rostedt@goodmis.org, mingo@redhat.com, davem@davemloft.net,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        ast@kernel.org, kernel-team@fb.com, daniel@iogearbox.net,
        linux-btrfs@vger.kernel.org, darrick.wong@oracle.com,
        Josef Bacik <josef@toxicpanda.com>,
        Akinobu Mita <akinobu.mita@gmail.com>
Subject: Re: [PATCH bpf-next v3 1/5] tracing/kprobe: bpf: Check error
 injectable event is on function entry
Message-ID: <20180110152138.fefzhdhuixljvapo@destiny>
References: <151557939382.6629.18074658376309258555.stgit@devbox>
 <151557942619.6629.4941380220602441478.stgit@devbox>
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On Wed, Jan 10, 2018 at 07:17:06PM +0900, Masami Hiramatsu wrote:
> Check whether error injectable event is on function entry or not.
> Currently it checks the event is ftrace-based kprobes or not,
> but that is wrong. It should check if the event is on the entry
> of target function. Since error injection will override a function
> to just return with modified return value, that operation must
> be done before the target function starts making stackframe.
> 
> As a side effect, bpf error injection is no need to depend on
> function-tracer. It can work with sw-breakpoint based kprobe
> events too.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>

Reviewed-by: Josef Bacik <jbacik@fb.com>

Thanks,

Josef