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session: avoid debug half-open session pool contention

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Half-opens are only allocated from main with worker barrier but can be
cleaned up, i.e., session_half_open_free, from main without a barrier.
In debug images, the free_bitmap can grow while workers peek the
sessions pool, e.g., session_half_open_migrate_notify, and as a result
crash while validating the session. To avoid, proactively grow bitmap in
debug images.

Type: fix

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: I2410793f933fb638651fe8dc08ba78e9bee0bd77
This commit is contained in:
Florin Coras
2022-02-09 19:17:02 -08:00
committed by Florin Coras
parent 794599bcca
commit f8c8809d00
1 changed files with 11 additions and 0 deletions
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11
src/vnet/session/session.h
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@@ -676,6 +676,17 @@ ho_session_alloc (void)
s = session_alloc (0);
s->session_state = SESSION_STATE_CONNECTING;
s->flags |= SESSION_F_HALF_OPEN;
/* Not ideal. Half-opens are only allocated from main with worker barrier
* but can be cleaned up, i.e., session_half_open_free, from main without
* a barrier. In debug images, the free_bitmap can grow while workers peek
* the sessions pool, e.g., session_half_open_migrate_notify, and as a
* result crash while validating the session. To avoid this, grow the bitmap
* now. */
if (CLIB_DEBUG)
{
session_t *sp = session_main.wrk[0].sessions;
clib_bitmap_validate (pool_header (sp)->free_bitmap, s->session_index);
}
return s;
}