Re: [PATCH v7 3/5] tcp: Resend SYN for inbound connections

7 Nov 2025

      On Wed, Nov 5, 2025 at 3:01 PM Stefano Brivio  wrote:
...
On Wed, 5 Nov 2025 15:24:44 +1100
David Gibson  wrote:
...
On Tue, Nov 04, 2025 at 05:42:33AM +0100, Stefano Brivio wrote:
...
On Fri, 31 Oct 2025 13:42:40 +0800
Yumei Huang  wrote:
[snip]
...
+/**
+ * tcp_get_rto_params() - Get host kernel RTO parameters
+ * @c:           Execution context
+*/
+void tcp_get_rto_params(struct ctx *c)
+{
+ intmax_t tcp_syn_retries, syn_linear_timeouts;
+
+ tcp_syn_retries = read_file_integer(
+         TCP_SYN_RETRIES, TCP_SYN_RETRIES_DEFAULT);
+ syn_linear_timeouts = read_file_integer(
+         TCP_SYN_LINEAR_TIMEOUTS, TCP_SYN_LINEAR_TIMEOUTS_DEFAULT);
I think this is a bit hard to read. Now:
tcp_syn_retries = read_file_integer(TCP_SYN_RETRIES,
                                        TCP_SYN_RETRIES_DEFAULT);
    syn_linear_timeouts = read_file_integer(TCP_SYN_LINEAR_TIMEOUTS,
                                            TCP_SYN_LINEAR_TIMEOUTS_DEFAULT);
would be a bit closer to the coding style we're adopting, but I wonder:
- does read_file_integer() really need to have "integer" in the name?
...
In a language where integers are called 'int', perhaps
  read_file_int() is clear enough?
I think the idea is that read_file_integer() can be used for any
(signed) integer type (with range checking performed after the call).
read_file_int() might suggest it reads exactly an 'int', not anything
bigger or smaller.
Oh, I see. It could be read_file_num() then, even if it's slightly less
accurate, or it can even remain read_file_integer(). If something like
this:
v = read_file_integer(SYN_RETRIES, SYN_RETRIES_DEFAULT);
        c->tcp.tcp_syn_retries = MIN(v, UINT8_MAX);
v = read_file_integer(SYN_LINEAR_TIMEOUTS, SYN_LINEAR_TIMEOUTS_DEFAULT);
        c->tcp.syn_linear_timeouts = MIN(v, UINT8_MAX);
fits 80 columns, I'm taking it as a sign that the function name isn't
exceedingly long. No particular preference from me.
The longest line just exceeds 80 columns. I can rename the function to
read_file_num() if there is no objection from David.

Another thing, while I was revising the patches, I noticed the
parameter "const struct ctx *c" was removed from tcp_timer_ctl() by
commit dd5302dd7bf51 ("tcp, flow: Replace per-connection in_epoll flag
with an epollid in flow_common") from Laurent, but we need it to
access c->tcp.syn_retries and c->tcp.syn_linear_timeouts. Should we
add it back?

(Adding Laurent in the loop.)

-- 
Thanks,

Yumei Huang