Date: Thu, 17 Dec 2015 22:19:30 -0800
From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: "Wangnan (F)" <wangnan0@huawei.com>
Cc: ast@kernel.org, agartrell@fb.com, acme@redhat.com, bblanco@plumgrid.com,
        daniel@iogearbox.net, daniel.wagner@bmw-carit.de, davem@davemloft.net,
        mingo@kernel.org, jolsa@kernel.org, xiakaixu@huawei.com,
        holzheu@linux.vnet.ibm.com, yang.shi@linaro.org,
        linux-kernel@vger.kernel.org, pi3orama@163.com
Subject: Re: [PATCH 08/10] bpf samples: Add utils.[ch] for using BPF
Message-ID: <20151218061929.GA59584@ast-mbp.thefacebook.com>
References: <1450329794-161948-1-git-send-email-wangnan0@huawei.com>
 <1450329794-161948-9-git-send-email-wangnan0@huawei.com>
 <20151217231138.GA34078@ast-mbp.thefacebook.com>
 <5673659F.9090004@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <5673659F.9090004@huawei.com>
User-Agent: Mutt/1.5.24 (2015-08-30)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1576
Lines: 46

On Fri, Dec 18, 2015 at 09:47:11AM +0800, Wangnan (F) wrote:
> 
> This is a limitation in tools/lib/bpf/libbpf.h, which has a #include
> <linux/err.h>
> in its header.
> 
> libbpf.h requires this include because its API uses ERR_PTR() to encode
> error code.
> For example, when calling bpf_object__open(), caller should use IS_ERR() to
> check its
> return value instead of compare with NULL, and use PTR_ERR() to retrive
> error number.
> 
> However, linux/err.h is not a part of uapi. To make libbpf work, one has to
> create its
> own err.h.

Why tools/include/linux/err.h is not suitable for everyone?

> Now I'm thinking provide LIBBPF_{IS_ERR,PTR_ERR}(),  in libbpf itself.

seems odd. we already have user space err.h in tools/include.

> And I don't touch the setsockopt in all patches.

ok, but where is the bit that does attach to perf_event to make trace_output work?

> Orignally they are macros defined in linux/filter.h.

no. they were never part of offical filter.h. Only in my earlier versions
of bpf patches, but we decided to drop them before they got into net-next.

> What about moving them into include/uapi/linux/filter.h ? Then
> normal user programs like those in samples/bpf can access
> them easier.

we don't want to add these macros to uapi.
Why not to add it to
tools/include/linux/filter.h
instead?

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/