git: f9668e42b44f - main - Add rib_walk_from() wrapper for selective rib tree traversal.

[Alexander V. Chernikov]

The branch main has been updated by melifaro:

URL: https://cgit.FreeBSD.org/src/commit/?id=f9668e42b44f22c9ab213eb9a4792d5acfcf6903

commit f9668e42b44f22c9ab213eb9a4792d5acfcf6903
Author:     Alexander V. Chernikov <melifaro at FreeBSD.org>
AuthorDate: 2021-04-25 11:59:40 +0000
Commit:     Alexander V. Chernikov <melifaro at FreeBSD.org>
CommitDate: 2021-04-28 08:09:45 +0000

    Add rib_walk_from() wrapper for selective rib tree traversal.
    
    Provide wrapper for the rnh_walktree_from() rib callback.
    As currently `struct rib_head` is considered internal to the
     routing subsystem, this wrapper is necessary to maintain isolation
     from the external code.
    
    Differential Revision: https://reviews.freebsd.org/D29971
    MFC after:      1 week
---
 sys/net/route/route_ctl.h     |  6 ++++++
 sys/net/route/route_helpers.c | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/sys/net/route/route_ctl.h b/sys/net/route/route_ctl.h
index 46dba759f8df..4fe45cc8a970 100644
--- a/sys/net/route/route_ctl.h
+++ b/sys/net/route/route_ctl.h
@@ -62,6 +62,10 @@ int rib_add_redirect(u_int fibnum, struct sockaddr *dst,
   struct sockaddr *gateway, struct sockaddr *author, struct ifnet *ifp,
   int flags, int expire_sec);
 
+/* common flags for the functions below */
+#define	RIB_FLAG_WLOCK		0x01	/* Need exclusive rnh lock */
+#define	RIB_FLAG_LOCKED		0x02	/* Do not explicitly acquire rnh lock */
+
 enum rib_walk_hook {
 	RIB_WALK_HOOK_PRE,	/* Hook is called before iteration */
 	RIB_WALK_HOOK_POST,	/* Hook is called after iteration */
@@ -77,6 +81,8 @@ void rib_walk_ext_internal(struct rib_head *rnh, bool wlock,
     rib_walktree_f_t *wa_f, rib_walk_hook_f_t *hook_f, void *arg);
 void rib_walk_ext_locked(struct rib_head *rnh, rib_walktree_f_t *wa_f,
     rib_walk_hook_f_t *hook_f, void *arg);
+void rib_walk_from(uint32_t fibnum, int family, uint32_t flags, struct sockaddr *prefix,
+    struct sockaddr *mask, rib_walktree_f_t *wa_f, void *arg);
 
 void rib_walk_del(u_int fibnum, int family, rib_filter_f_t *filter_f,
     void *arg, bool report);
diff --git a/sys/net/route/route_helpers.c b/sys/net/route/route_helpers.c
index 782e160ca51b..5d29197cc4fb 100644
--- a/sys/net/route/route_helpers.c
+++ b/sys/net/route/route_helpers.c
@@ -128,6 +128,38 @@ rib_walk(uint32_t fibnum, int family, bool wlock, rib_walktree_f_t *wa_f,
 	rib_walk_ext(fibnum, family, wlock, wa_f, NULL, arg);
 }
 
+/*
+ * Calls @wa_f with @arg for each entry in the table matching @prefix/@mask.
+ *
+ * The following flags are supported:
+ *  RIB_FLAG_WLOCK: acquire exclusive lock
+ *  RIB_FLAG_LOCKED: Assumes the table is already locked & skip locking
+ *
+ * By default, table is traversed under read lock.
+ */
+void
+rib_walk_from(uint32_t fibnum, int family, uint32_t flags, struct sockaddr *prefix,
+    struct sockaddr *mask, rib_walktree_f_t *wa_f, void *arg)
+{
+	RIB_RLOCK_TRACKER;
+	struct rib_head *rnh = rt_tables_get_rnh(fibnum, family);
+
+	if (rnh == NULL)
+		return;
+
+	if (flags & RIB_FLAG_WLOCK)
+		RIB_WLOCK(rnh);
+	else if (!(flags & RIB_FLAG_LOCKED))
+		RIB_RLOCK(rnh);
+
+	rnh->rnh_walktree_from(&rnh->head, prefix, mask, (walktree_f_t *)wa_f, arg);
+
+	if (flags & RIB_FLAG_WLOCK)
+		RIB_WUNLOCK(rnh);
+	else if (!(flags & RIB_FLAG_LOCKED))
+		RIB_RUNLOCK(rnh);
+}
+
 /*
  * Iterates over all existing fibs in system calling
  *  @hook_f function before/after traversing each fib.