path: root/drivers/hid/hid-debug.c
diff options
authorRasmus Villemoes <linux@rasmusvillemoes.dk>2015-11-24 13:33:47 +0100
committerJiri Kosina <jkosina@suse.cz>2015-11-27 00:02:59 +0100
commit92529623d242cea4440958d7bcebdf291f4ab15e (patch)
tree642b9391e9d698fd623a640582264c7f33ba3042 /drivers/hid/hid-debug.c
parentcc8a9d79222c6b259ea9eceef21b94a5610616f0 (diff)
HID: debug: improve hid_debug_event()
The code in hid_debug_event() causes horrible code generation. First, we do a strlen() call for every byte we copy (we're doing a store to global memory, so gcc has no way of proving that strlen(buf) doesn't change). Second, since both i, list->tail and HID_DEBUG_BUFSIZE have signed type, the modulo computation has to take into account the possibility that list->tail+i is negative, so it's not just a simple and. Fix the former by simply not doing strlen() at all (we have to load buf[i] anyway, so testing it is almost free) and the latter by changing i to unsigned. This cuts 29% (69 bytes) of the size of the function. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'drivers/hid/hid-debug.c')
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/hid/hid-debug.c b/drivers/hid/hid-debug.c
index 2886b645ced7..acfb522a432a 100644
--- a/drivers/hid/hid-debug.c
+++ b/drivers/hid/hid-debug.c
@@ -659,13 +659,13 @@ EXPORT_SYMBOL_GPL(hid_dump_device);
/* enqueue string to 'events' ring buffer */
void hid_debug_event(struct hid_device *hdev, char *buf)
- int i;
+ unsigned i;
struct hid_debug_list *list;
unsigned long flags;
spin_lock_irqsave(&hdev->debug_list_lock, flags);
list_for_each_entry(list, &hdev->debug_list, node) {
- for (i = 0; i < strlen(buf); i++)
+ for (i = 0; buf[i]; i++)
list->hid_debug_buf[(list->tail + i) % HID_DEBUG_BUFSIZE] =
list->tail = (list->tail + i) % HID_DEBUG_BUFSIZE;

Privacy Policy