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perf_counter: Fix perf_output_copy() WARN to account for overflow 

The simple reservation test in perf_output_copy() failed to take
unsigned int overflow into account, fix this.

[ Impact: fix false positive warning with more than 4GB of profiling data ]

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-05-13 21:26:19 +02:00 committed by Ingo Molnar
parent a026dfecc0
commit 53020fe81e
1 changed files with 5 additions and 1 deletions
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6
kernel/perf_counter.c
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@ -1927,7 +1927,11 @@ static void perf_output_copy(struct perf_output_handle *handle,
handle->offset = offset;
WARN_ON_ONCE(handle->offset > handle->head);
/*
* Check we didn't copy past our reservation window, taking the
* possible unsigned int wrap into account.
*/
WARN_ON_ONCE(((int)(handle->head - handle->offset)) < 0);
}
#define perf_output_put(handle, x) \