diff options
| author | Rasmus Villemoes <linux@rasmusvillemoes.dk> | 2015-11-24 13:33:47 +0100 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2019-03-25 17:32:34 +0000 |
| commit | 9e23e2c5535a8e7c77ab3a01f92fa4ab5f15e91e (patch) | |
| tree | b1e909caa9a9fff90ad7a459410bd62c39efb80a | |
| parent | f9d19815c8092240f168275e29bd16ad321eeee8 (diff) | |
HID: debug: improve hid_debug_event()
commit 92529623d242cea4440958d7bcebdf291f4ab15e upstream.
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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | drivers/hid/hid-debug.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/hid/hid-debug.c b/drivers/hid/hid-debug.c index 3f6019dc190b..c243ead44fd7 100644 --- a/drivers/hid/hid-debug.c +++ b/drivers/hid/hid-debug.c @@ -658,13 +658,13 @@ 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] = buf[i]; list->tail = (list->tail + i) % HID_DEBUG_BUFSIZE; |