Re: [PATCH net-next v4 3/5] net/ipv6: Remove expired routes with a separated list of routes.
From: David Ahern <dsahern@kernel.org>
Date: 2024-02-07 15:58:06
On 2/5/24 2:40 PM, thinker.li@gmail.com wrote:
From: Kui-Feng Lee <redacted> FIB6 GC walks trees of fib6_tables to remove expired routes. Walking a tree can be expensive if the number of routes in a table is big, even if most of them are permanent. Checking routes in a separated list of routes having expiration will avoid this potential issue. Signed-off-by: Kui-Feng Lee <redacted> --- include/net/ip6_fib.h | 47 ++++++++++++++++++++++++++++++++- net/ipv6/addrconf.c | 41 ++++++++++++++++++++++++----- net/ipv6/ip6_fib.c | 60 +++++++++++++++++++++++++++++++++++++++---- net/ipv6/ndisc.c | 10 +++++++- net/ipv6/route.c | 13 ++++++++-- 5 files changed, 155 insertions(+), 16 deletions(-)
one nit below, but otherwise Reviewed-by: David Ahern <dsahern@kernel.org>
quoted hunk ↗ jump to hunk
@@ -498,6 +510,39 @@ void fib6_gc_cleanup(void); int fib6_init(void); +/* Add the route to the gc list if it is not already there + * + * The callers should hold f6i->fib6_table->tb6_lock and make sure the + * route is on a table.
The last comment is not correct given the fib6_node check below.
+ */
+static inline void fib6_add_gc_list(struct fib6_info *f6i)
+{
+ /* If fib6_node is null, the f6i is not in (or removed from) the
+ * table.
+ *
+ * There is a gap between finding the f6i from the table and
+ * calling this function without the protection of the tb6_lock.
+ * This check makes sure the f6i is not added to the gc list when
+ * it is not on the table.
+ */
+ if (!rcu_dereference_protected(f6i->fib6_node,
+ lockdep_is_held(&f6i->fib6_table->tb6_lock)))
+ return;
+
+ if (hlist_unhashed(&f6i->gc_link))
+ hlist_add_head(&f6i->gc_link, &f6i->fib6_table->tb6_gc_hlist);
+}
+