perf_counter: sanity check on the output API
Ensure we never write more than we said we would. Signed-off-by: Peter 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: Ingo Molnar <mingo@elte.hu>
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@ -1422,6 +1422,7 @@ struct perf_output_handle {
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struct perf_counter *counter;
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struct perf_counter *counter;
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struct perf_mmap_data *data;
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struct perf_mmap_data *data;
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unsigned int offset;
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unsigned int offset;
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unsigned int head;
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int wakeup;
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int wakeup;
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};
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};
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@ -1447,6 +1448,7 @@ static int perf_output_begin(struct perf_output_handle *handle,
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handle->counter = counter;
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handle->counter = counter;
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handle->data = data;
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handle->data = data;
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handle->offset = offset;
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handle->offset = offset;
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handle->head = head;
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handle->wakeup = (offset >> PAGE_SHIFT) != (head >> PAGE_SHIFT);
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handle->wakeup = (offset >> PAGE_SHIFT) != (head >> PAGE_SHIFT);
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return 0;
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return 0;
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@ -1485,6 +1487,8 @@ static void perf_output_copy(struct perf_output_handle *handle,
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} while (len);
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} while (len);
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handle->offset = offset;
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handle->offset = offset;
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WARN_ON_ONCE(handle->offset > handle->head);
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}
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}
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#define perf_output_put(handle, x) \
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#define perf_output_put(handle, x) \
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