tracing/ipv4/ipv6: Use static array for name field in fib*_lookup_table event

The fib_lookup_table and fib6_lookup_table events declare name as a
dynamic_array, but also give it a fixed size, which defeats the purpose of
the dynamic array, especially since the dynamic array also includes meta
data in the event to specify its size.

Since the size of the name is at most 16 bytes (defined by IFNAMSIZ),
it is not worth spending the effort to determine the size of the string.

Just use a fixed size array and copy into it. This will save 4 bytes that
are used for the meta data that saves the size and position of a dynamic
array, and even slightly speed up the event processing.

Link: https://lkml.kernel.org/r/20220704091436.3705edbf@rorschach.local.home
Cc: David S. Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Acked-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/include/trace/events/fib.h b/include/trace/events/fib.h
index 6f2a4dc35e37eae4d302055d195ac2fc2b67089b..c2300c407f58325768032b4b7bcd7e83714f7564 100644 (file)
--- a/include/trace/events/fib.h
+++ b/include/trace/events/fib.h
@@ -32,7 +32,7 @@ TRACE_EVENT(fib_table_lookup,
                __array(        __u8,   gw6,    16      )
                __field(        u16,    sport           )
                __field(        u16,    dport           )
-               __dynamic_array(char,  name,   IFNAMSIZ )
+               __array(char,  name,   IFNAMSIZ )
        ),
 
        TP_fast_assign(
@@ -66,7 +66,7 @@ TRACE_EVENT(fib_table_lookup,
                }
 
                dev = nhc ? nhc->nhc_dev : NULL;
-               __assign_str(name, dev ? dev->name : "-");
+               strlcpy(__entry->name, dev ? dev->name : "-", IFNAMSIZ);
 
                if (nhc) {
                        if (nhc->nhc_gw_family == AF_INET) {
@@ -95,7 +95,7 @@ TRACE_EVENT(fib_table_lookup,
                  __entry->tb_id, __entry->oif, __entry->iif, __entry->proto,
                  __entry->src, __entry->sport, __entry->dst, __entry->dport,
                  __entry->tos, __entry->scope, __entry->flags,
-                 __get_str(name), __entry->gw4, __entry->gw6, __entry->err)
+                 __entry->name, __entry->gw4, __entry->gw6, __entry->err)
 );
 #endif /* _TRACE_FIB_H */
 

diff --git a/include/trace/events/fib6.h b/include/trace/events/fib6.h
index c6abdcc77c1276df9a947af435295b1d4e9cd766..6e821eb7945033dc6ec89964e3b30fa3027966d0 100644 (file)
--- a/include/trace/events/fib6.h
+++ b/include/trace/events/fib6.h
@@ -31,7 +31,7 @@ TRACE_EVENT(fib6_table_lookup,
                __field(        u16,    dport           )
                __field(        u8,     proto           )
                __field(        u8,     rt_type         )
-               __dynamic_array(        char,   name,   IFNAMSIZ )
+               __array(                char,   name,   IFNAMSIZ )
                __array(                __u8,   gw,     16       )
        ),
 
@@ -63,9 +63,9 @@ TRACE_EVENT(fib6_table_lookup,
                }
 
                if (res->nh && res->nh->fib_nh_dev) {
-                       __assign_str(name, res->nh->fib_nh_dev);
+                       strlcpy(__entry->name, res->nh->fib_nh_dev->name, IFNAMSIZ);
                } else {
-                       __assign_str(name, "-");
+                       strcpy(__entry->name, "-");
                }
                if (res->f6i == net->ipv6.fib6_null_entry) {
                        struct in6_addr in6_zero = {};
@@ -83,7 +83,7 @@ TRACE_EVENT(fib6_table_lookup,
                  __entry->tb_id, __entry->oif, __entry->iif, __entry->proto,
                  __entry->src, __entry->sport, __entry->dst, __entry->dport,
                  __entry->tos, __entry->scope, __entry->flags,
-                 __get_str(name), __entry->gw, __entry->err)
+                 __entry->name, __entry->gw, __entry->err)
 );
 
 #endif /* _TRACE_FIB6_H */