Ensure we never write more than we said we would. Signed-off-by: Peter Zijlstra --- kernel/perf_counter.c | 4 ++++ 1 file changed, 4 insertions(+) Index: linux-2.6/kernel/perf_counter.c =================================================================== --- linux-2.6.orig/kernel/perf_counter.c +++ linux-2.6/kernel/perf_counter.c @@ -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 handle->counter = counter; handle->data = data; handle->offset = offset; + handle->head = head; handle->wakeup = (offset >> PAGE_SHIFT) != (head >> PAGE_SHIFT); return 0; @@ -1478,6 +1480,8 @@ static void perf_output_copy(struct perf } while (len); handle->offset = offset; + + WARN_ON(handle->offset > handle->head); } #define perf_output_put(handle, x) \ -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/