Emerson, Am 03.01.19 um 21:58 schrieb Emerson Gomes: > However, the underflow scenario only seem to be possible if the peers are > sending relative values, rather than absolute ones.
I don't believe so. My hypothetical timeline was created with absolute values in mind. > Apparently both cases (absolut and offset values) exist. > I am looking at src/peers.c to understand how the peer protocol works and > maybe create the patch you proposed (do not decrement counter if already 0). I attached a patch which I believe fixes the issue (checking for 0 when decrementing, not touching the peers). > However it seems that a real fix would require some big changes on the > protocol itself. Yes I agree. > One potencial implementation I could imagine, would be to, rather than > broadcasting absolute values or offsets, each neighbor peer could report > the amount of connection it has locally only, and it would be up to the > local node to resolve the actual value by adding up the different values > received from all neighbors. Yes, that probably would be the most reliable implementation. It takes up more memory and processing power, though. > Not even sure if my understading is correct, but it's task currently out of > my reach. > Should I do a bug report somewhere? :) > I suspect that the developers will notice this thread. A proper issue tracker is a wish of mine as well (https://www.mail-archive.com/[email protected]/msg32239.html). Best regards Tim Düsterhus
From 10a271fb167c23d6db628f225bdc8be15d1a400a Mon Sep 17 00:00:00 2001 From: Tim Duesterhus <[email protected]> Date: Fri, 4 Jan 2019 00:11:59 +0100 Subject: [PATCH] BUG/MINOR: stick_table: Prevent conn_cur from underflowing When using the peers feature a race condition could prevent a connection from being properly counted. When this connection exits it is being "uncounted" nonetheless, leading to a possible underflow (-1) of the conn_curr stick table entry. --- include/proto/session.h | 3 ++- include/proto/stream.h | 6 ++++-- 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/include/proto/session.h b/include/proto/session.h index d54e9454..0b7d08d9 100644 --- a/include/proto/session.h +++ b/include/proto/session.h @@ -62,7 +62,8 @@ static inline void session_store_counters(struct session *sess) if (ptr) { HA_RWLOCK_WRLOCK(STK_SESS_LOCK, &ts->lock); - stktable_data_cast(ptr, conn_cur)--; + if (stktable_data_cast(ptr, conn_cur) > 0) + stktable_data_cast(ptr, conn_cur)--; HA_RWLOCK_WRUNLOCK(STK_SESS_LOCK, &ts->lock); diff --git a/include/proto/stream.h b/include/proto/stream.h index f4482097..a8c29921 100644 --- a/include/proto/stream.h +++ b/include/proto/stream.h @@ -103,7 +103,8 @@ static inline void stream_store_counters(struct stream *s) if (ptr) { HA_RWLOCK_WRLOCK(STK_SESS_LOCK, &ts->lock); - stktable_data_cast(ptr, conn_cur)--; + if (stktable_data_cast(ptr, conn_cur) > 0) + stktable_data_cast(ptr, conn_cur)--; HA_RWLOCK_WRUNLOCK(STK_SESS_LOCK, &ts->lock); @@ -141,7 +142,8 @@ static inline void stream_stop_content_counters(struct stream *s) if (ptr) { HA_RWLOCK_WRLOCK(STK_SESS_LOCK, &ts->lock); - stktable_data_cast(ptr, conn_cur)--; + if (stktable_data_cast(ptr, conn_cur) > 0) + stktable_data_cast(ptr, conn_cur)--; HA_RWLOCK_WRUNLOCK(STK_SESS_LOCK, &ts->lock); -- 2.20.1
