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netflow: Back-out optimization that could lead to infinite loop

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Commit 924282 (netflow: Do 64-bit division less often.) attempted to
remove the 64-bit division used to break flow records with large byte
counts into multiple NetFlow records.  The calculation to determine the
number of records was incorrect and should have shifted "byte_delta" by
31 instead of 32.  This commit reverts the change (while keeping commit
f22a24 (netflow: Avoid (theoretically) looping 2**32 times.) ), since
the logic is more straight-forward than the optimized version.

Bug #3813
This commit is contained in:
Justin Pettit
2010-10-12 11:24:04 -07:00
parent f1670a487a
commit c06955bc63
1 changed files with 2 additions and 5 deletions
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7
ofproto/netflow.c
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@@ -190,8 +190,8 @@ netflow_expire(struct netflow *nf, struct netflow_flow *nf_flow,
* traffic. We try to evenly distribute the packet and byte counters, * traffic. We try to evenly distribute the packet and byte counters,
* so that the bytes-per-packet lengths don't look wonky across the * so that the bytes-per-packet lengths don't look wonky across the
* records. */ * records. */
while (byte_delta > UINT32_MAX) { while (byte_delta) {
uint32_t n_recs = byte_delta >> 32; int n_recs = (byte_delta + UINT32_MAX - 1) / UINT32_MAX;
uint32_t pkt_count = pkt_delta / n_recs; uint32_t pkt_count = pkt_delta / n_recs;
uint32_t byte_count = byte_delta / n_recs; uint32_t byte_count = byte_delta / n_recs;
@@ -200,9 +200,6 @@ netflow_expire(struct netflow *nf, struct netflow_flow *nf_flow,
pkt_delta -= pkt_count; pkt_delta -= pkt_count;
byte_delta -= byte_count; byte_delta -= byte_count;
} }
if (byte_delta > 0) {
gen_netflow_rec(nf, nf_flow, expired, pkt_delta, byte_delta);
}
} else { } else {
/* In 600 seconds, a 10GbE link can theoretically transmit 75 * 10**10 /* In 600 seconds, a 10GbE link can theoretically transmit 75 * 10**10
* == 175 * 2**32 bytes. The byte counter is bigger than that, so it's * == 175 * 2**32 bytes. The byte counter is bigger than that, so it's