From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann Subject: Re: [PATCH net 2/3] bpf, mlx5: fix various refcount/prog issues in mlx5e_xdp_set Date: Mon, 14 Nov 2016 09:49:49 +0100 Message-ID: <58297AAD.8060003@iogearbox.net> References: <03741f7075af64e83d23add379bdab41204396b0.1479080215.git.daniel@iogearbox.net> <20161114024908.GB94347@ast-mbp.thefacebook.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: davem@davemloft.net, bblanco@plumgrid.com, tariqt@mellanox.com, zhiyisun@gmail.com, ranas@mellanox.com, netdev@vger.kernel.org To: Alexei Starovoitov Return-path: Received: from www62.your-server.de ([213.133.104.62]:36674 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932562AbcKNIt4 (ORCPT ); Mon, 14 Nov 2016 03:49:56 -0500 In-Reply-To: <20161114024908.GB94347@ast-mbp.thefacebook.com> Sender: netdev-owner@vger.kernel.org List-ID: On 11/14/2016 03:49 AM, Alexei Starovoitov wrote: > On Mon, Nov 14, 2016 at 01:43:41AM +0100, Daniel Borkmann wrote: [...] >> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c >> index 751e806..a0fca9f 100644 >> --- a/kernel/bpf/syscall.c >> +++ b/kernel/bpf/syscall.c >> @@ -682,6 +682,17 @@ struct bpf_prog *bpf_prog_add(struct bpf_prog *prog, int i) >> } >> EXPORT_SYMBOL_GPL(bpf_prog_add); >> >> +void bpf_prog_sub(struct bpf_prog *prog, int i) >> +{ >> + /* Only to be used for undoing previous bpf_prog_add() in some >> + * error path. We still know that another entity in our call >> + * path holds a reference to the program, thus atomic_sub() can >> + * be safely used in such cases! >> + */ >> + WARN_ON(atomic_sub_return(i, &prog->aux->refcnt) == 0); >> +} >> +EXPORT_SYMBOL_GPL(bpf_prog_sub); > > the patches look good. I'm only worried about net/net-next merge > conflict here. (I would have to deal with it as well). > So instead of copying the above helper can we apply net-next's > 'bpf, mlx4: fix prog refcount in mlx4_en_try_alloc_resources error path' > patch to net without mlx4_xdp_set hunk and then apply > the rest of this patch? > Even better is to send this patch 2/3 to net-next? > yes, it's an issue, but very small one. There is no security > concern here, so I would prefer to avoid merge conflict. > Did you do a test merge of net/net-next by any chance? Yes, I did a test merge and git resolved the above just fine w/o any conflicts. I have no strong opinion whether net or net-next. If preferred, I can just resend this series in the evening against net-next instead, perhaps that's a bit better. Thanks, Daniel