git: 0abb6ff59084 - main - fib algo: do not reallocate datapath index for datapath ptr update.

[Alexander V. Chernikov]

The branch main has been updated by melifaro:

URL: https://cgit.FreeBSD.org/src/commit/?id=0abb6ff590842114c74e5d52e1af65605bd9d960

commit 0abb6ff590842114c74e5d52e1af65605bd9d960
Author:     Alexander V. Chernikov <melifaro at FreeBSD.org>
AuthorDate: 2021-04-18 15:03:58 +0000
Commit:     Alexander V. Chernikov <melifaro at FreeBSD.org>
CommitDate: 2021-04-18 15:12:13 +0000

    fib algo: do not reallocate datapath index for datapath ptr update.
    
    Fib algo uses a per-family array indexed by the fibnum to store
     lookup function pointers and per-fib data.
    
    Each algorithm rebuild currently requires re-allocating this array
     to support atomic change of two pointers.
    
    As in reality most of the changes actually involve changing only
     data pointer, add a shortcut performing in-flight pointer update.
    
    MFC after:      2 weeks
---
 sys/net/route/fib_algo.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/sys/net/route/fib_algo.c b/sys/net/route/fib_algo.c
index b0a6c38ff560..30e715e1e1ef 100644
--- a/sys/net/route/fib_algo.c
+++ b/sys/net/route/fib_algo.c
@@ -1561,6 +1561,17 @@ replace_rtables_family(struct fib_dp **pdp, struct fib_data *fd, struct fib_dp *
 	FIB_MOD_LOCK();
 	old_fdh = get_fib_dp_header(*pdp);
 
+	if (old_fdh->fdh_idx[fd->fd_fibnum].f == dp->f) {
+		/*
+		 * Function is the same, data pointer needs update.
+		 * Perform in-line replace without reallocation.
+		 */
+		old_fdh->fdh_idx[fd->fd_fibnum].arg = dp->arg;
+		FD_PRINTF(LOG_DEBUG, fd, "FDH %p inline update", old_fdh);
+		FIB_MOD_UNLOCK();
+		return (true);
+	}
+
 	new_fdh = alloc_fib_dp_array(old_fdh->fdh_num_tables, false);
 	FD_PRINTF(LOG_DEBUG, fd, "OLD FDH: %p NEW FDH: %p", old_fdh, new_fdh);
 	if (new_fdh == NULL) {