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Fix wrap-around in memusage.

This commit is contained in:
Andreas Schwab 2009-10-29 11:25:20 -07:00 committed by Ulrich Drepper
parent d94760f944
commit 22bc5239e1
2 changed files with 10 additions and 4 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
2009-10-29 Andreas Schwab <schwab@redhat.com>
* malloc/memusage.c (update_data): Fix index wraparound handling
so that buffer_cnt is actually reset.
2009-10-29 Ulrich Drepper <drepper@redhat.com>
[BZ #10784]

9
malloc/memusage.c
View File

@ -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);