On 6/3/23 4:25 AM, Shakeel Butt wrote:

On Fri, Jun 02, 2023 at 04:11:33PM +0800, Abel Wu wrote:

quoted

The callers of mem_cgroup_under_socket_pressure() should always make
sure that (mem_cgroup_sockets_enabled && sk->sk_memcg) is true. So
instead of coding around all the callsites, put the dependencies into
mem_cgroup_under_socket_pressure() to avoid redundancy and possibly
bugs.

This change might also introduce slight function call overhead *iff*
the function gets expanded in the future. But for now this change
doesn't make binaries different (checked by vimdiff) except the one
net/ipv4/tcp_input.o (by scripts/bloat-o-meter), which is probably
negligible to performance:

add/remove: 0/0 grow/shrink: 1/2 up/down: 5/-5 (0)
Function                                     old     new   delta
tcp_grow_window                              573     578      +5
tcp_try_rmem_schedule                       1083    1081      -2
tcp_check_space                              324     321      -3
Total: Before=44647, After=44647, chg +0.00%

So folding the dependencies into mem_cgroup_under_socket_pressure()
is generally a good thing and provides better readablility.

I don't see how it is improving readability. If you have removed the use
of mem_cgroup_sockets_enabled completely from the networking then I can
understand but this change IMHO will actually decrease the readability
because the later readers will have to reason why we are doing this
check at some places but not other.

Yes, I agree. I am trying to let networking get rid of this macro
entirely, but get stuck on inet_csk_accept().. :(