Messages in this thread | | | From | shaozhengchao <> | Subject | 答复: 答复: [PATCH bpf-next] samples/bpf: check detach prog exist or not in xdp fwd | Date | Tue, 17 May 2022 02:00:52 +0000 |
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-----邮件原件----- 发件人: Toke Høiland-Jørgensen [mailto:toke@kernel.org] 发送时间: 2022年5月9日 18:55 收件人: shaozhengchao <shaozhengchao@huawei.com>; bpf@vger.kernel.org; netdev@vger.kernel.org; linux-kernel@vger.kernel.org; ast@kernel.org; daniel@iogearbox.net; davem@davemloft.net; kuba@kernel.org; hawk@kernel.org; john.fastabend@gmail.com; andrii@kernel.org; kafai@fb.com; songliubraving@fb.com; yhs@fb.com; kpsingh@kernel.org 抄送: weiyongjun (A) <weiyongjun1@huawei.com>; yuehaibing <yuehaibing@huawei.com> 主题: Re: 答复: [PATCH bpf-next] samples/bpf: check detach prog exist or not in xdp_fwd
shaozhengchao <shaozhengchao@huawei.com> writes:
> -----邮件原件----- > 发件人: Toke Høiland-Jørgensen [mailto:toke@kernel.org] > 发送时间: 2022年5月9日 17:46 > 收件人: shaozhengchao <shaozhengchao@huawei.com>; bpf@vger.kernel.org; > netdev@vger.kernel.org; linux-kernel@vger.kernel.org; ast@kernel.org; > daniel@iogearbox.net; davem@davemloft.net; kuba@kernel.org; > hawk@kernel.org; john.fastabend@gmail.com; andrii@kernel.org; > kafai@fb.com; songliubraving@fb.com; yhs@fb.com; kpsingh@kernel.org > 抄送: weiyongjun (A) <weiyongjun1@huawei.com>; shaozhengchao > <shaozhengchao@huawei.com>; yuehaibing <yuehaibing@huawei.com> > 主题: Re: [PATCH bpf-next] samples/bpf: check detach prog exist or not > in xdp_fwd > > Zhengchao Shao <shaozhengchao@huawei.com> writes: > >> Before detach the prog, we should check detach prog exist or not. > > If we're adding such a check we should also check that it's the *right* program. I.e., query the ID for the program name and check that it matches what the program attached, then obtain an fd and pass that as XDP_EXPECTED_FD on detach to make sure it wasn't swapped out in the meantime... > > -Toke > > Thank you for your reply. When finish running xdp_fwd to attatch prog, > the program will exit and can't store fd as XDP_EXPECTED_FD. > > I think the sample xdp_fwd -d is just detach prog and don't care if > the fd is expected.
So why are you adding the check? Either keep it the way it is, or add a proper check that examines the program type; you're right that it doesn't store the prog FD, but you can still check the program name and see if it matches to get some idea that it's not a totally separate program that's loaded. I think doing so would be an improvement to the sample, but just adding a check if a program is loaded is not, really...
-Toke
Could I add helper function to implement this function which can check the program name and see if it attach to the device.
-Zhengchao Shao
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