Author: kp
Date: Fri Dec 11 14:11:41 2020
New Revision: 368552
URL: https://svnweb.freebsd.org/changeset/base/368552
Log:
MFC r368015:
if: Remove ifnet_rwlock
It no longer serves any purpose, as evidenced by the fact that we never take
it
without ifnet_sxlock.
This differs slightly from r368015 in that we keep the ifnet_rwlock instance
(but no longer take the lock) in case there are external users who still take
the lock.
Sponsored by: Modirum MDPay
Modified:
stable/12/sys/net/if.c
stable/12/sys/net/if_var.h
Directory Properties:
stable/12/ (props changed)
Modified: stable/12/sys/net/if.c
==============================================================================
--- stable/12/sys/net/if.c Fri Dec 11 13:23:59 2020 (r368551)
+++ stable/12/sys/net/if.c Fri Dec 11 14:11:41 2020 (r368552)
@@ -305,12 +305,8 @@ VNET_DEFINE(struct ifnet **, ifindex_table);
/*
* The global network interface list (V_ifnet) and related state (such as
- * if_index, if_indexlim, and ifindex_table) are protected by an sxlock and
- * an rwlock. Either may be acquired shared to stablize the list, but both
- * must be acquired writable to modify the list. This model allows us to
- * both stablize the interface list during interrupt thread processing, but
- * also to stablize it over long-running ioctls, without introducing priority
- * inversions and deadlocks.
+ * if_index, if_indexlim, and ifindex_table) are protected by an sxlock.
+ * This may be acquired to stabilise the list, or we may rely on NET_EPOCH.
*/
struct rwlock ifnet_rwlock;
RW_SYSINIT_FLAGS(ifnet_rw, &ifnet_rwlock, "ifnet_rw", RW_RECURSE);
Modified: stable/12/sys/net/if_var.h
==============================================================================
--- stable/12/sys/net/if_var.h Fri Dec 11 13:23:59 2020 (r368551)
+++ stable/12/sys/net/if_var.h Fri Dec 11 14:11:41 2020 (r368552)
@@ -569,27 +569,11 @@ struct ifmultiaddr {
extern struct rwlock ifnet_rwlock;
extern struct sx ifnet_sxlock;
-#define IFNET_WLOCK() do {
\
- sx_xlock(&ifnet_sxlock); \
- rw_wlock(&ifnet_rwlock); \
-} while (0)
-
-#define IFNET_WUNLOCK() do {
\
- rw_wunlock(&ifnet_rwlock); \
- sx_xunlock(&ifnet_sxlock); \
-} while (0)
-
-/*
- * To assert the ifnet lock, you must know not only whether it's for read or
- * write, but also whether it was acquired with sleep support or not.
- */
-#define IFNET_RLOCK_ASSERT() sx_assert(&ifnet_sxlock,
SA_SLOCKED)
+#define IFNET_WLOCK() sx_xlock(&ifnet_sxlock)
+#define IFNET_WUNLOCK() sx_xunlock(&ifnet_sxlock)
+#define IFNET_RLOCK_ASSERT() sx_assert(&ifnet_sxlock, SA_SLOCKED)
#define IFNET_RLOCK_NOSLEEP_ASSERT()
MPASS(in_epoch(net_epoch_preempt))
-#define IFNET_WLOCK_ASSERT() do {
\
- sx_assert(&ifnet_sxlock, SA_XLOCKED); \
- rw_assert(&ifnet_rwlock, RA_WLOCKED); \
-} while (0)
-
+#define IFNET_WLOCK_ASSERT() sx_assert(&ifnet_sxlock, SA_XLOCKED)
#define IFNET_RLOCK() sx_slock(&ifnet_sxlock)
#define IFNET_RLOCK_NOSLEEP() struct epoch_tracker ifnet_rlock_et;
epoch_enter_preempt(net_epoch_preempt, &ifnet_rlock_et)
#define IFNET_RUNLOCK() sx_sunlock(&ifnet_sxlock)
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