diff options
| author | Jakub Kicinski <kuba@kernel.org> | 2022-10-19 13:00:09 -0700 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2022-10-19 13:00:10 -0700 |
| commit | 5c624a1d77d3eb2e314b59282b1213fa760d192c (patch) | |
| tree | a063036b4c78b6cde4e1819b602d5137767c0728 /include/linux/netlink.h | |
| parent | a526a3cc9c8d426713f8bebc18ebbe39a8495d82 (diff) | |
| parent | b799f052a987c3fdd315cbac665b9202dd96382b (diff) | |
Merge branch 'netlink-formatted-extacks'
Edward Cree says:
====================
netlink: formatted extacks
Currently, netlink extacks can only carry fixed string messages, which
is limiting when reporting failures in complex systems. This series
adds the ability to return printf-formatted messages, and uses it in
the sfc driver's TC offload code.
Formatted extack messages are limited in length to a fixed buffer size,
currently 80 characters. If the message exceeds this, the full message
will be logged (ratelimited) to the console and a truncated version
returned over netlink.
There is no change to the netlink uAPI; only internal kernel changes
are needed.
====================
Link: https://lore.kernel.org/r/cover.1666102698.git.ecree.xilinx@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'include/linux/netlink.h')
| -rw-r--r-- | include/linux/netlink.h | 29 |
1 files changed, 27 insertions, 2 deletions
diff --git a/include/linux/netlink.h b/include/linux/netlink.h index d51e041d2242..d81bde5a5844 100644 --- a/include/linux/netlink.h +++ b/include/linux/netlink.h @@ -64,6 +64,7 @@ netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg) /* this can be increased when necessary - don't expose to userland */ #define NETLINK_MAX_COOKIE_LEN 20 +#define NETLINK_MAX_FMTMSG_LEN 80 /** * struct netlink_ext_ack - netlink extended ACK report struct @@ -75,6 +76,8 @@ netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg) * @miss_nest: nest missing an attribute (%NULL if missing top level attr) * @cookie: cookie data to return to userspace (for success) * @cookie_len: actual cookie data length + * @_msg_buf: output buffer for formatted message strings - don't access + * directly, use %NL_SET_ERR_MSG_FMT */ struct netlink_ext_ack { const char *_msg; @@ -84,13 +87,13 @@ struct netlink_ext_ack { u16 miss_type; u8 cookie[NETLINK_MAX_COOKIE_LEN]; u8 cookie_len; + char _msg_buf[NETLINK_MAX_FMTMSG_LEN]; }; /* 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.) + * If string formatting is needed use NL_SET_ERR_MSG_FMT. */ #define NL_SET_ERR_MSG(extack, msg) do { \ static const char __msg[] = msg; \ @@ -102,9 +105,31 @@ struct netlink_ext_ack { __extack->_msg = __msg; \ } while (0) +/* We splice fmt with %s at each end even in the snprintf so that both calls + * can use the same string constant, avoiding its duplication in .ro + */ +#define NL_SET_ERR_MSG_FMT(extack, fmt, args...) do { \ + struct netlink_ext_ack *__extack = (extack); \ + \ + if (!__extack) \ + break; \ + if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \ + "%s" fmt "%s", "", ##args, "") >= \ + NETLINK_MAX_FMTMSG_LEN) \ + net_warn_ratelimited("%s" fmt "%s", "truncated extack: ", \ + ##args, "\n"); \ + \ + do_trace_netlink_extack(__extack->_msg_buf); \ + \ + __extack->_msg = __extack->_msg_buf; \ +} while (0) + #define NL_SET_ERR_MSG_MOD(extack, msg) \ NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg) +#define NL_SET_ERR_MSG_FMT_MOD(extack, fmt, args...) \ + NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args) + #define NL_SET_BAD_ATTR_POLICY(extack, attr, pol) do { \ if ((extack)) { \ (extack)->bad_attr = (attr); \ |