On Mon, Mar 23, 2026 at 02:33:07PM +0530, Anshu Kumari wrote:
Hi Everyone,
Please review patch for Bug 134.
Description:- Inorder to rate limit the messages, each logging function uses per-call-site static variables, so each macro expansion tracks its own rate independently. Allows up to LOG_RATELIMIT_BURST messages per window. When a new window starts after suppression, a summary of suppressed messages is logged.
Signed-off-by: Anshu Kumari
Logic looks good to me, and more straightforward than I feared. Nice! Stefano had a bunch of boring procedural things to fix, and I have one more, see below.
--- log.h | 41 +++++++++++++++++++++++++++++++++++++++++ tap.c | 19 ++++++------------- 2 files changed, 47 insertions(+), 13 deletions(-)
diff --git a/log.h b/log.h index 6ceb686..e989760 100644 --- a/log.h +++ b/log.h @@ -48,6 +48,47 @@ void logmsg_perror(int pri, const char *format, ...) passt_exit(EXIT_FAILURE); \ } while (0)
+#define LOG_RATELIMIT_BURST 5 /* Max messages per window per call site */ +#define LOG_RATELIMIT_INTERVAL 1 /* Default rate limit window in seconds */ + +/** + * logmsg_ratelimit() - Rate-limited log message + * @fn: Logging function + * @now: current timestamp + * @intv: Minimum interval in seconds between allowed messages + */ +#define logmsg_ratelimit(fn, now, intv, ...) \ + do { \ + static time_t _rl_last; \
Identifiers starting with _ are reserved for "the system" (vague, I know). The kernel can get away with this, because it controls every part of the build. We're a normal userspace binary, though, linked against the C library, so we should avoid this. Doing something to avoiding shadowing regular variables in the macro is wise though. For this, I usually use _ as a suffix instead of a prefix (see, e.g. flow_log()).
+ static unsigned int _rl_printed; \ + static unsigned int _rl_suppressed; \ + \ + if ((now)->tv_sec - _rl_last > (intv)) { \ + if (_rl_suppressed) \ + fn("(suppressed %u similar messages)", \ + _rl_suppressed); \ + _rl_last = (now)->tv_sec; \ + _rl_printed = 0; \ + _rl_suppressed = 0; \ + } \ + \ + if (_rl_printed < LOG_RATELIMIT_BURST) { \ + fn(__VA_ARGS__); \ + _rl_printed++; \ + } else { \ + _rl_suppressed++; \ + } \ + } while (0) + +#define err_ratelimit(now, intv, ...) \ + logmsg_ratelimit(err, now, intv, __VA_ARGS__) +#define warn_ratelimit(now, intv, ...) \ + logmsg_ratelimit(warn, now, intv, __VA_ARGS__) +#define info_ratelimit(now, intv, ...) \ + logmsg_ratelimit(info, now, intv, __VA_ARGS__) +#define debug_ratelimit(now, intv, ...) \ + logmsg_ratelimit(debug, now, intv, __VA_ARGS__) + extern int log_file; extern int log_trace; extern bool log_conf_parsed; diff --git a/tap.c b/tap.c index 1049e02..0812a8a 100644 --- a/tap.c +++ b/tap.c @@ -686,17 +686,8 @@ static bool tap4_is_fragment(const struct iphdr *iph, const struct timespec *now) { if (ntohs(iph->frag_off) & ~IP_DF) { - /* Ratelimit messages */ - static time_t last_message; - static unsigned num_dropped; - - num_dropped++; - if (now->tv_sec - last_message > FRAGMENT_MSG_RATE) { - warn("Can't process IPv4 fragments (%u dropped)", - num_dropped); - last_message = now->tv_sec; - num_dropped = 0; - } + warn_ratelimit(now, FRAGMENT_MSG_RATE, + "Can't process IPv4 fragment"); return true; } return false; @@ -1115,8 +1106,10 @@ void tap_add_packet(struct ctx *c, struct iov_tail *data, char bufmac[ETH_ADDRSTRLEN];
memcpy(c->guest_mac, eh->h_source, ETH_ALEN); - debug("New guest MAC address observed: %s", - eth_ntop(c->guest_mac, bufmac, sizeof(bufmac))); + info_ratelimit(now, LOG_RATELIMIT_INTERVAL, + "New guest MAC address observed: %s", + eth_ntop(c->guest_mac, bufmac, + sizeof(bufmac))); proto_update_l2_buf(c->guest_mac); }
-- 2.53.0
-- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson