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Commit 63e35b25 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf_counter: sanity check on the output API 



Ensure we never write more than we said we would.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Orig-LKML-Reference: <20090325113316.921433024@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 5c148194

kernel/perf_counter.c

+4 −0
Original line number Diff line number Diff line
@@ -1422,6 +1422,7 @@ struct perf_output_handle { 
	struct perf_counter	*counter;

	struct perf_mmap_data	*data;

	unsigned int		offset;

	unsigned int		head;

	int			wakeup;

};
@@ -1447,6 +1448,7 @@ static int perf_output_begin(struct perf_output_handle *handle, 
	handle->counter	= counter;

	handle->data	= data;

	handle->offset	= offset;

	handle->head	= head;

	handle->wakeup	= (offset >> PAGE_SHIFT) != (head >> PAGE_SHIFT);



	return 0;
@@ -1485,6 +1487,8 @@ static void perf_output_copy(struct perf_output_handle *handle, 
	} while (len);



	handle->offset = offset;



	WARN_ON_ONCE(handle->offset > handle->head);

}



#define perf_output_put(handle, x) \