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if: Remove ifnet_rwlock

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It no longer serves any purpose, as evidenced by the fact that we never take it
without ifnet_sxlock.

Sponsored by:	Modirum MDPay
Differential Revision:	https://reviews.freebsd.org/D27278
This commit is contained in:
Kristof Provost 2020-11-25 10:56:38 +00:00
parent 6b8f0ba8e2
commit a60100fdfc
2 changed files with 6 additions and 29 deletions
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10
sys/net/if.c
View File

@ -306,15 +306,9 @@ 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);
struct sx ifnet_sxlock;
SX_SYSINIT_FLAGS(ifnet_sx, &ifnet_sxlock, "ifnet_sx", SX_RECURSE);

25
sys/net/if_var.h
View File

@ -593,29 +593,12 @@ struct ifmultiaddr {
struct epoch_context ifma_epoch_ctx;
};
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_ASSERT() do { \
sx_assert(&ifnet_sxlock, SA_XLOCKED); \
rw_assert(&ifnet_rwlock, RA_WLOCKED); \
} while (0)
#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_WLOCK_ASSERT() sx_assert(&ifnet_sxlock, SA_XLOCKED)
#define IFNET_RLOCK() sx_slock(&ifnet_sxlock)
#define IFNET_RUNLOCK() sx_sunlock(&ifnet_sxlock)