[RFC PATCH 04/11] net: add simple socket-like dst cache helpers
From: Paolo Abeni <pabeni@redhat.com>
Date: 2017-09-22 21:07:04
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
It will be used by later patches to reduce code duplication. Signed-off-by: Paolo Abeni <pabeni@redhat.com> --- include/net/dst.h | 20 ++++++++++++++++++++ net/core/dst.c | 12 ++++++++++++ 2 files changed, 32 insertions(+)
diff --git a/include/net/dst.h b/include/net/dst.h
index 93568bd0a352..4fcca0e368c6 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h@@ -485,6 +485,26 @@ static inline struct dst_entry *dst_check(struct dst_entry *dst, u32 cookie) return dst; } +/* update the cache with dst, assuming the latter already carries a refcount */ +static inline bool __dst_update(struct dst_entry **cache, struct dst_entry *dst) +{ + struct dst_entry *old = xchg(cache, dst); + + dst_release(old); + return old != dst; +} +bool dst_update(struct dst_entry **cache, struct dst_entry *dst); +static inline struct dst_entry *dst_access(struct dst_entry **cache, + u32 cookie) +{ + struct dst_entry *dst = READ_ONCE(*cache); + + if (!dst) + return NULL; + + return dst_check(dst, cookie); +} + /* Flags for xfrm_lookup flags argument. */ enum { XFRM_LOOKUP_ICMP = 1 << 0,
diff --git a/net/core/dst.c b/net/core/dst.c
index a6c47da7d0f8..4076f9af45d7 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c@@ -205,6 +205,18 @@ void dst_release_immediate(struct dst_entry *dst) } EXPORT_SYMBOL(dst_release_immediate); +/* update the cache with dst, assuming the latter does not carry a refcount */ +bool dst_update(struct dst_entry **cache, struct dst_entry *dst) +{ + if (likely(*cache == dst)) + return false; + + if (dst_hold_safe(dst)) + return __dst_update(cache, dst); + return false; +} +EXPORT_SYMBOL_GPL(dst_update); + u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old) { struct dst_metrics *p = kmalloc(sizeof(*p), GFP_ATOMIC);
--
2.13.5