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From 22bc5239e1c7d97b0642af6c135af994586f8e82 Mon Sep 17 00:00:00 2001
From: Andreas Schwab <schwab@redhat.com>
Date: Thu, 29 Oct 2009 11:25:20 -0700
Subject: [PATCH 3/3] Fix wrap-around in memusage.
---
malloc/memusage.c | 9 +++++----
1 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/malloc/memusage.c b/malloc/memusage.c
index fcd58dc..382261c 100644
--- a/malloc/memusage.c
+++ b/malloc/memusage.c
@@ -163,15 +163,16 @@ update_data (struct header *result, size_t len, size_t old_len)
if (fd != -1)
{
uatomic32_t idx = catomic_exchange_and_add (&buffer_cnt, 1);
- if (idx >= 2 * buffer_size)
+ if (idx + 1 >= 2 * buffer_size)
{
/* We try to reset the counter to the correct range. If
this fails because of another thread increasing the
counter it does not matter since that thread will take
care of the correction. */
- uatomic32_t reset = idx % (2 * buffer_size);
- catomic_compare_and_exchange_val_acq (&buffer_cnt, reset, idx);
- idx = reset;
+ uatomic32_t reset = (idx + 1) % (2 * buffer_size);
+ catomic_compare_and_exchange_val_acq (&buffer_cnt, reset, idx + 1);
+ if (idx >= 2 * buffer_size)
+ idx = reset - 1;
}
assert (idx < 2 * DEFAULT_BUFFER_SIZE);
--
1.6.3.3
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