git: cf32543fa4fa - main - tcp: document that conditional fields in tcpcb should be at the end

The branch main has been updated by tuexen:

URL: https://cgit.FreeBSD.org/src/commit/?id=cf32543fa4faded1b1d17f7aa1335cd249320088

commit cf32543fa4faded1b1d17f7aa1335cd249320088
Author:     Michael Tuexen <tuexen@FreeBSD.org>
AuthorDate: 2023-07-27 07:02:19 +0000
Commit:     Michael Tuexen <tuexen@FreeBSD.org>
CommitDate: 2023-07-27 07:02:19 +0000

    tcp: document that conditional fields in tcpcb should be at the end
    
    Reviewed by:    rscheff, Peter Lei
    Sponsored by:   Netflix, Inc.
---
 sys/netinet/tcp_var.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/sys/netinet/tcp_var.h b/sys/netinet/tcp_var.h
index 0f57fec74865..d6d071676089 100644
--- a/sys/netinet/tcp_var.h
+++ b/sys/netinet/tcp_var.h
@@ -471,6 +471,11 @@ struct tcpcb {
 	};
 	struct osd	t_osd;		/* storage for Khelp module data */
 	uint8_t _t_logpoint;	/* Used when a BB log points is enabled */
+	/*
+	 * Keep all #ifdef'ed components at the end of the structure!
+	 * This is important to minimize problems when compiling modules
+	 * using this structure from within the modules' directory.
+	 */
 #ifdef TCP_REQUEST_TRK
 	/* Response tracking addons. */
 	uint8_t t_tcpreq_req;	/* Request count */