Python-BCC: support fmod_ret attaching method, and add a useful tool for mptcp #5274
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Dwyane-Yan
requested review from
drzaeus77,
goldshtn,
davemarchevsky and
brendangregg
as code owners
chenhengqi
reviewed
Apr 9, 2025
chenhengqi
reviewed
Apr 10, 2025
chenhengqi
reviewed
Apr 14, 2025
matttbe
reviewed
Apr 15, 2025
added 3 commits
April 21, 2025 10:54
Followed by the suggestions of Hengqi, which judging the kernel whether supported 'fmod_ret' by using 'kernel_struct_has_field' to check the existence of enum 'BPF_MODIFY_RETURN'. But, the 'kernel_struct_has_filed' is not supported the 'enum' type, so this patch provides an interface 'kernel_enum_has_val' to achieve this. Co-developed-by: Geliang Tang <[email protected]> Signed-off-by: Geliang Tang <[email protected]> Signed-off-by: Gang Yan <[email protected]>
In kernel, there exists a lot of 'fmod_ret' functions, such as 'update_socket_protocol'. But it cannot attached in BCC-python directly, so this patch provides an interface for python to use 'fmod_ret' attaching method. This patch is suggested by Yonghong: ''' On Sun, 2024-08-25 at 21:05 -0700, Yonghong Song wrote: ... > Gang Yan, could you explore to add fmod_ret support in bcc? It should > be similar to kfunc/kretfunc support. I am happy to review your patches. ''' And the method to check 'fmod_ret' support in kernel is from Hengqi. Co-developed-by: Geliang Tang <[email protected]> Signed-off-by: Geliang Tang <[email protected]> Signed-off-by: Gang Yan <[email protected]>
Multipath TCP (MPTCP) is an extension of the standard TCP protocol that allows a single transport connection to use multiple network interfaces or paths. MPTCP is useful for applications like bandwidth aggregation, failover, and more resilient connections. Linux kernel starts to support MPTCP since v5.6, this patch provides a method which can easily force applications use MPTCP socket without modifing its code. Co-developed-by: Geliang Tang <[email protected]> Signed-off-by: Geliang Tang <[email protected]> Signed-off-by: Gang Yan <[email protected]>
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Hi @chenhengqi and @yonghong-song, It was truly delightful to receive your valuable suggestions regarding this pull request. I'm pleased to inform you that all the issues have now been addressed. Would you mind taking another look at it when you have a moment? Thank you so much！ |
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Multipath TCP (MPTCP) serves as an enhancement to the conventional TCP
protocol, enabling a single transport-layer connection to leverage
multiple network interfaces. This capability makes MPTCP advantageous
for applications requiring bandwidth consolidation, seamless failover
mechanisms, and more robust connectivity solutions.
Linux kernel starts to support MPTCP since v5.6, and it provides a
fmod_ret interface 'update_socket_protocol' to force applications using
MPTCP instead of TCP without modifyiing its code.
So these patches provide a tool named 'mptcpify' which can achieve this.
Using python-BCC is a more easy way for future development, so it is so
important to support 'fmod_ret' in python-BCC.
The first patch is suggested by Yonghong:
‘’‘
On Sun, 2024-08-25 at 21:05 -0700, Yonghong Song wrote:
...
> Gang Yan, could you explore to add fmod_ret support in bcc? It should
> be similar to kfunc/kretfunc support. I am happy to review your patches.
’‘’
when I try to make a commit to kernel. (Link attached below)
https://patchwork.kernel.org/project/netdevbpf/patch/[email protected]/
@matttbe from the MPTCP kernel team had a look at the new tool.