The want was to have some separate object section for netlink messages
so all netlink messages could be specifically listed by some tool but
the effect is duplicating static const char arrays in the object code.
It seems unused presently so change the macro to avoid the local static
declarations until such time as these actually are wanted and used.
This reduces object size ~8KB in an x86-64 defconfig without modules.
$ size vmlinux.o*
text data bss dec hex filename
20110471 3460344 741760 24312575 172faff vmlinux.o.new
20119444 3460344 741760 24321548 1731e0c vmlinux.o.old
Signed-off-by: Joe Perches <[email protected]>
---
include/linux/netlink.h | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 61b1c7fcc401e..4bb32ae134aa8 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -89,13 +89,12 @@ struct netlink_ext_ack {
* to the lack of an output buffer.)
*/
#define NL_SET_ERR_MSG(extack, msg) do { \
- static const char __msg[] = msg; \
struct netlink_ext_ack *__extack = (extack); \
\
- do_trace_netlink_extack(__msg); \
+ do_trace_netlink_extack(msg); \
\
if (__extack) \
- __extack->_msg = __msg; \
+ __extack->_msg = msg; \
} while (0)
#define NL_SET_ERR_MSG_MOD(extack, msg) \
@@ -111,13 +110,12 @@ struct netlink_ext_ack {
#define NL_SET_BAD_ATTR(extack, attr) NL_SET_BAD_ATTR_POLICY(extack, attr, NULL)
#define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) do { \
- static const char __msg[] = msg; \
struct netlink_ext_ack *__extack = (extack); \
\
- do_trace_netlink_extack(__msg); \
+ do_trace_netlink_extack(msg); \
\
if (__extack) { \
- __extack->_msg = __msg; \
+ __extack->_msg = msg; \
__extack->bad_attr = (attr); \
__extack->policy = (pol); \
} \
On 8/9/21 1:04 PM, Joe Perches wrote:
> The want was to have some separate object section for netlink messages
> so all netlink messages could be specifically listed by some tool but
> the effect is duplicating static const char arrays in the object code.
>
> It seems unused presently so change the macro to avoid the local static
> declarations until such time as these actually are wanted and used.
>
> This reduces object size ~8KB in an x86-64 defconfig without modules.
>
> $ size vmlinux.o*
> text data bss dec hex filename
> 20110471 3460344 741760 24312575 172faff vmlinux.o.new
> 20119444 3460344 741760 24321548 1731e0c vmlinux.o.old
>
> Signed-off-by: Joe Perches <[email protected]>
Seems reasonable.
Acked-by: Jonathan Toppins <[email protected]>
On Mon, 09 Aug 2021 10:04:00 -0700 Joe Perches wrote:
> The want was to have some separate object section for netlink messages
> so all netlink messages could be specifically listed by some tool but
> the effect is duplicating static const char arrays in the object code.
>
> It seems unused presently so change the macro to avoid the local static
> declarations until such time as these actually are wanted and used.
>
> This reduces object size ~8KB in an x86-64 defconfig without modules.
>
> $ size vmlinux.o*
> text data bss dec hex filename
> 20110471 3460344 741760 24312575 172faff vmlinux.o.new
> 20119444 3460344 741760 24321548 1731e0c vmlinux.o.old
>
> Signed-off-by: Joe Perches <[email protected]>
I guess we can bring it back when it's needed.
> diff --git a/include/linux/netlink.h b/include/linux/netlink.h
> index 61b1c7fcc401e..4bb32ae134aa8 100644
> --- a/include/linux/netlink.h
> +++ b/include/linux/netlink.h
> @@ -89,13 +89,12 @@ struct netlink_ext_ack {
> * to the lack of an output buffer.)
> */
> #define NL_SET_ERR_MSG(extack, msg) do { \
> - static const char __msg[] = msg; \
> struct netlink_ext_ack *__extack = (extack); \
> \
> - do_trace_netlink_extack(__msg); \
> + do_trace_netlink_extack(msg); \
> \
> if (__extack) \
> - __extack->_msg = __msg; \
> + __extack->_msg = msg; \
> } while (0)
But you've made us evaluate msg multiple times now.
Given extack is carefully evaluated only once this stands out.
> #define NL_SET_ERR_MSG_MOD(extack, msg) \
> @@ -111,13 +110,12 @@ struct netlink_ext_ack {
> #define NL_SET_BAD_ATTR(extack, attr) NL_SET_BAD_ATTR_POLICY(extack, attr, NULL)
>
> #define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) do { \
> - static const char __msg[] = msg; \
> struct netlink_ext_ack *__extack = (extack); \
> \
> - do_trace_netlink_extack(__msg); \
> + do_trace_netlink_extack(msg); \
> \
> if (__extack) { \
> - __extack->_msg = __msg; \
> + __extack->_msg = msg; \
> __extack->bad_attr = (attr); \
> __extack->policy = (pol); \
Same here.
On Tue, 2021-08-10 at 13:30 -0700, Jakub Kicinski wrote:
> On Mon, 09 Aug 2021 10:04:00 -0700 Joe Perches wrote:
> > The want was to have some separate object section for netlink messages
> > so all netlink messages could be specifically listed by some tool but
> > the effect is duplicating static const char arrays in the object code.
> >
> > It seems unused presently so change the macro to avoid the local static
> > declarations until such time as these actually are wanted and used.
> >
> > This reduces object size ~8KB in an x86-64 defconfig without modules.
[]
> > diff --git a/include/linux/netlink.h b/include/linux/netlink.h
[]
> > @@ -89,13 +89,12 @@ struct netlink_ext_ack {
> > ??* to the lack of an output buffer.)
> > ??*/
> > ?#define NL_SET_ERR_MSG(extack, msg) do { \
> > - static const char __msg[] = msg; \
> > ? struct netlink_ext_ack *__extack = (extack); \
> > ? \
> > - do_trace_netlink_extack(__msg); \
> > + do_trace_netlink_extack(msg); \
> > ? \
> > ? if (__extack) \
> > - __extack->_msg = __msg; \
> > + __extack->_msg = msg; \
> > ?} while (0)
>
> But you've made us evaluate msg multiple times now.
> Given extack is carefully evaluated only once this stands out.
msg is always a const char array so no evaluation is done.
It's just a pointer.
In fact, this could either become a static inline or a
simple function call to reduce object size even further.
For instance:
$ size vmlinux.o.nl_func.*
text data bss dec hex filename
19974564 3457991 741312 24173867 170dd2b vmlinux.o.nl_func.new
19992097 3457967 741312 24191376 1712190 vmlinux.o.nl_func.old
---
include/linux/netlink.h | 29 ++++++++++-------------------
net/netlink/af_netlink.c | 13 +++++++++++++
2 files changed, 23 insertions(+), 19 deletions(-)
diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 61b1c7fcc401e..fe80c2704cc23 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -82,21 +82,16 @@ struct netlink_ext_ack {
u8 cookie_len;
};
+void netlink_set_err_msg(struct netlink_ext_ack *extack, const char *msg);
/* Always use this macro, this allows later putting the
* message into a separate section or such for things
* like translation or listing all possible messages.
* Currently string formatting is not supported (due
* to the lack of an output buffer.)
*/
-#define NL_SET_ERR_MSG(extack, msg) do { \
- static const char __msg[] = msg; \
- struct netlink_ext_ack *__extack = (extack); \
- \
- do_trace_netlink_extack(__msg); \
- \
- if (__extack) \
- __extack->_msg = __msg; \
-} while (0)
+
+#define NL_SET_ERR_MSG(extack, msg) \
+ netlink_set_err_msg(extack, msg)
#define NL_SET_ERR_MSG_MOD(extack, msg) \
NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)
@@ -110,16 +105,12 @@ struct netlink_ext_ack {
#define NL_SET_BAD_ATTR(extack, attr) NL_SET_BAD_ATTR_POLICY(extack, attr, NULL)
-#define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) do { \
- static const char __msg[] = msg; \
- struct netlink_ext_ack *__extack = (extack); \
- \
- do_trace_netlink_extack(__msg); \
- \
- if (__extack) { \
- __extack->_msg = __msg; \
- __extack->bad_attr = (attr); \
- __extack->policy = (pol); \
+#define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) \
+do { \
+ netlink_set_err_msg(extack, msg); \
+ if (extack) { \
+ extack->bad_attr = (attr); \
+ extack->policy = (pol); \
} \
} while (0)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 24b7cf447bc55..b6d035f0d343b 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2561,6 +2561,19 @@ int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 portid,
}
EXPORT_SYMBOL(nlmsg_notify);
+/**
+ * nl_set_err_msg -
+ */
+
+void netlink_set_err_msg(struct netlink_ext_ack *extack, const char *msg)
+{
+ do_trace_netlink_extack(msg);
+
+ if (extack)
+ extack->_msg = msg;
+}
+EXPORT_SYMBOL(netlink_set_err_msg);
+
#ifdef CONFIG_PROC_FS
struct nl_seq_iter {
struct seq_net_private p;