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Reuse hash table bucket entries if they're stale 32+ seconds
[flowspec-xdp]
/
xdp.c
diff --git
a/xdp.c
b/xdp.c
index 6a8c19e4f852bad1e108093332043d0033f8e55b..ad6ab82db97feedc53f88f9f9f3f067d65bcbb7f 100644
(file)
--- a/
xdp.c
+++ b/
xdp.c
@@
-185,6
+185,11
@@
struct {
#define RATE_BUCKET_BITS (RATE_BUCKET_DECIMAL_BITS + RATE_BUCKET_INTEGER_BITS)
#define RATE_TIME_MASK ((1ULL << (64 - RATE_BUCKET_BITS)) - 1)
#define RATE_BUCKET_BITS (RATE_BUCKET_DECIMAL_BITS + RATE_BUCKET_INTEGER_BITS)
#define RATE_TIME_MASK ((1ULL << (64 - RATE_BUCKET_BITS)) - 1)
+// Time going backwards 10ms+ or forward 32sec+ implies we should consider it
+// an overflow, or at least stale enough that we should reset the entry.
+#define RATE_MIN_TIME_OFFSET -10000000LL
+#define RATE_MAX_TIME_OFFSET 32000000000LL
+
#ifdef RATE_CNT
struct ratelimit {
struct bpf_spin_lock lock;
#ifdef RATE_CNT
struct ratelimit {
struct bpf_spin_lock lock;
@@
-232,7
+237,7
@@
struct persrc_rate##IPV##_ptr { \
}; \
\
__attribute__((always_inline)) \
}; \
\
__attribute__((always_inline)) \
-static inline struct persrc_rate##IPV##_ptr get_v##IPV##_persrc_ratelimit(IP_TYPE key, void *map, size_t map_limit) { \
+static inline struct persrc_rate##IPV##_ptr get_v##IPV##_persrc_ratelimit(IP_TYPE key, void *map, size_t map_limit
, int64_t cur_time_masked
) { \
struct persrc_rate##IPV##_ptr res = { .rate = NULL, .lock = NULL }; \
uint64_t hash = siphash(&key, sizeof(key), COMPILE_TIME_RAND); \
\
struct persrc_rate##IPV##_ptr res = { .rate = NULL, .lock = NULL }; \
uint64_t hash = siphash(&key, sizeof(key), COMPILE_TIME_RAND); \
\
@@
-253,7
+258,13
@@
static inline struct persrc_rate##IPV##_ptr get_v##IPV##_persrc_ratelimit(IP_TYP
res.rate = &first_bucket[i]; \
res.lock = &buckets->lock; \
return res; \
res.rate = &first_bucket[i]; \
res.lock = &buckets->lock; \
return res; \
- } else if (min_sent_time > (first_bucket[i].sent_time & RATE_TIME_MASK)) { \
+ } \
+ int64_t time_offset = ((int64_t)cur_time_masked) - (first_bucket[i].sent_time & RATE_TIME_MASK); \
+ if (time_offset < RATE_MIN_TIME_OFFSET || time_offset > RATE_MAX_TIME_OFFSET) { \
+ min_sent_idx = i; \
+ break; \
+ } \
+ if ((first_bucket[i].sent_time & RATE_TIME_MASK) < min_sent_time) { \
min_sent_time = first_bucket[i].sent_time & RATE_TIME_MASK; \
min_sent_idx = i; \
} \
min_sent_time = first_bucket[i].sent_time & RATE_TIME_MASK; \
min_sent_idx = i; \
} \