Re: [PATCH net] net/smc: avoid overwriting when adjusting sock bufsizes

From: Wenjia Zhang
Date: Tue Jun 04 2024 - 11:10:38 EST




On 04.06.24 16:04, Paolo Abeni wrote:
On Fri, 2024-05-31 at 16:54 +0800, Wen Gu wrote:
When copying smc settings to clcsock, avoid setting clcsock's sk_sndbuf
to sysctl_tcp_wmem[1], since this may overwrite the value set by
tcp_sndbuf_expand() in TCP connection establishment.

And the other setting sk_{snd|rcv}buf to sysctl value in
smc_adjust_sock_bufsizes() can also be omitted since the initialization
of smc sock and clcsock has set sk_{snd|rcv}buf to smc.sysctl_{w|r}mem
or ipv4_sysctl_tcp_{w|r}mem[1].

Fixes: 30c3c4a4497c ("net/smc: Use correct buffer sizes when switching between TCP and SMC")
Link: https://lore.kernel.org/r/5eaf3858-e7fd-4db8-83e8-3d7a3e0e9ae2@xxxxxxxxxxxxxxxxx
Signed-off-by: Wen Gu <guwen@xxxxxxxxxxxxxxxxx>
---
FYI,
The detailed motivation and testing can be found in the link above.

My understanding is that there is an open question here if this is the
expected and desired behavior.

@Wenjia, @Jan: could you please have a look?

Thanks!

Paolo

@Paolo, thank you for reminding us!

@Wen, Gerd and I have looked into your patch and discussed on it. Gerd would send the concrete answer to your question soon.

Regarding to this patch, it looks good to me. Here you are:

Reviewed-by: Wenjia Zhang <wenjia@xxxxxxxxxxxxx>

Thanks,
Wenjia