* [PATCH] HID: simplify implement() a bit
@ 2016-04-06 17:19 Dmitry Torokhov
2016-04-06 21:31 ` Doug Anderson
2016-04-07 13:46 ` Jiri Kosina
0 siblings, 2 replies; 3+ messages in thread
From: Dmitry Torokhov @ 2016-04-06 17:19 UTC (permalink / raw)
To: Jiri Kosina; +Cc: Benjamin Tissoires, Doug Anderson, linux-input, linux-kernel
The 'size' variable is not really needed, and we can also shift constant
in the loop body when masking off existing bits.
Also we do not have to us 64 bit calculations if we take an extra
branch.
Suggested-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
drivers/hid/hid-core.c | 33 +++++++++++++++------------------
1 file changed, 15 insertions(+), 18 deletions(-)
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 264cc49..9673dea 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1129,49 +1129,46 @@ EXPORT_SYMBOL_GPL(hid_field_extract);
static void __implement(u8 *report, unsigned offset, int n, u32 value)
{
unsigned int idx = offset / 8;
- unsigned int size = offset + n;
unsigned int bit_shift = offset % 8;
int bits_to_set = 8 - bit_shift;
- u8 bit_mask = 0xff << bit_shift;
while (n - bits_to_set >= 0) {
- report[idx] &= ~bit_mask;
+ report[idx] &= ~(0xff << bit_shift);
report[idx] |= value << bit_shift;
value >>= bits_to_set;
n -= bits_to_set;
bits_to_set = 8;
- bit_mask = 0xff;
bit_shift = 0;
idx++;
}
/* last nibble */
if (n) {
- if (size % 8)
- bit_mask &= (1U << (size % 8)) - 1;
- report[idx] &= ~bit_mask;
- report[idx] |= (value << bit_shift) & bit_mask;
+ u8 bit_mask = ((1U << n) - 1);
+ report[idx] &= ~(bit_mask << bit_shift);
+ report[idx] |= value << bit_shift;
}
}
static void implement(const struct hid_device *hid, u8 *report,
unsigned offset, unsigned n, u32 value)
{
- u64 m;
-
- if (n > 32) {
+ if (unlikely(n > 32)) {
hid_warn(hid, "%s() called with n (%d) > 32! (%s)\n",
__func__, n, current->comm);
n = 32;
+ } else if (n < 32) {
+ u32 m = (1U << n) - 1;
+
+ if (unlikely(value > m)) {
+ hid_warn(hid,
+ "%s() called with too large value %d (n: %d)! (%s)\n",
+ __func__, value, n, current->comm);
+ WARN_ON(1);
+ value &= m;
+ }
}
- m = (1ULL << n) - 1;
- if (value > m)
- hid_warn(hid, "%s() called with too large value %d! (%s)\n",
- __func__, value, current->comm);
- WARN_ON(value > m);
- value &= m;
-
__implement(report, offset, n, value);
}
--
2.8.0.rc3.226.g39d4020
--
Dmitry
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] HID: simplify implement() a bit
2016-04-06 17:19 [PATCH] HID: simplify implement() a bit Dmitry Torokhov
@ 2016-04-06 21:31 ` Doug Anderson
2016-04-07 13:46 ` Jiri Kosina
1 sibling, 0 replies; 3+ messages in thread
From: Doug Anderson @ 2016-04-06 21:31 UTC (permalink / raw)
To: Dmitry Torokhov
Cc: Jiri Kosina, Benjamin Tissoires, linux-input, linux-kernel
Dmitry,
On Wed, Apr 6, 2016 at 10:19 AM, Dmitry Torokhov
<dmitry.torokhov@gmail.com> wrote:
> The 'size' variable is not really needed, and we can also shift constant
> in the loop body when masking off existing bits.
>
> Also we do not have to us 64 bit calculations if we take an extra
> branch.
>
> Suggested-by: Doug Anderson <dianders@chromium.org>
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> ---
> drivers/hid/hid-core.c | 33 +++++++++++++++------------------
> 1 file changed, 15 insertions(+), 18 deletions(-)
Reviewed-by: Douglas Anderson <dianders@chromium.org>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] HID: simplify implement() a bit
2016-04-06 17:19 [PATCH] HID: simplify implement() a bit Dmitry Torokhov
2016-04-06 21:31 ` Doug Anderson
@ 2016-04-07 13:46 ` Jiri Kosina
1 sibling, 0 replies; 3+ messages in thread
From: Jiri Kosina @ 2016-04-07 13:46 UTC (permalink / raw)
To: Dmitry Torokhov
Cc: Benjamin Tissoires, Doug Anderson, linux-input, linux-kernel
On Wed, 6 Apr 2016, Dmitry Torokhov wrote:
> The 'size' variable is not really needed, and we can also shift constant
> in the loop body when masking off existing bits.
>
> Also we do not have to us 64 bit calculations if we take an extra
> branch.
>
> Suggested-by: Doug Anderson <dianders@chromium.org>
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Applied to for-4.7/upstream. Thanks!
--
Jiri Kosina
SUSE Labs
^ permalink raw reply [flat|nested] 3+ messages in thread
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2016-04-06 17:19 [PATCH] HID: simplify implement() a bit Dmitry Torokhov
2016-04-06 21:31 ` Doug Anderson
2016-04-07 13:46 ` Jiri Kosina
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