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-rw-r--r--Documentation/input/ff.txt4
1 files changed, 3 insertions, 1 deletions
diff --git a/Documentation/input/ff.txt b/Documentation/input/ff.txt
index ded4d5f53109..b3867bf49f8f 100644
--- a/Documentation/input/ff.txt
+++ b/Documentation/input/ff.txt
@@ -49,7 +49,9 @@ This information is subject to change.
#include <linux/input.h>
#include <sys/ioctl.h>
-unsigned long features[1 + FF_MAX/sizeof(unsigned long)];
+#define BITS_TO_LONGS(x) \
+ (((x) + 8 * sizeof (unsigned long) - 1) / (8 * sizeof (unsigned long)))
+unsigned long features[BITS_TO_LONGS(FF_CNT)];
int ioctl(int file_descriptor, int request, unsigned long *features);
"request" must be EVIOCGBIT(EV_FF, size of features array in bytes )