2015-03-03 04:20:49

by Fred Chou

Subject: [PATCH] ath9k_htc: avoid memcpy when downloading firmware

From: Fred Chou <[email protected]>

The temporary buffer to hold firmware data is not really needed,
and memcpy can be avoided by using data pointer instead.

Signed-off-by: Fred Chou <[email protected]>
---
drivers/net/wireless/ath/ath9k/hif_usb.c | 12 ++----------
1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
index 10c02f5..0bc35a8 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.c
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
@@ -986,30 +986,22 @@ static int ath9k_hif_usb_download_fw(struct hif_device_usb *hif_dev)
const void *data = hif_dev->fw_data;
size_t len = hif_dev->fw_size;
u32 addr = AR9271_FIRMWARE;
- u8 *buf = kzalloc(4096, GFP_KERNEL);
u32 firm_offset;

- if (!buf)
- return -ENOMEM;
-
while (len) {
transfer = min_t(size_t, len, 4096);
- memcpy(buf, data, transfer);

err = usb_control_msg(hif_dev->udev,
usb_sndctrlpipe(hif_dev->udev, 0),
FIRMWARE_DOWNLOAD, 0x40 | USB_DIR_OUT,
- addr >> 8, 0, buf, transfer, HZ);
- if (err < 0) {
- kfree(buf);
+ addr >> 8, 0, data, transfer, HZ);
+ if (err < 0)
return err;
- }

len -= transfer;
data += transfer;
addr += transfer;
}
- kfree(buf);

if (IS_AR7010_DEVICE(hif_dev->usb_device_id->driver_info))
firm_offset = AR7010_FIRMWARE_TEXT;
--
1.9.1

2015-03-03 06:00:10

by Eric Dumazet

Subject: Re: [PATCH] ath9k_htc: avoid memcpy when downloading firmware

On Tue, 2015-03-03 at 12:24 +0800, Fred Chou wrote:
> From: Fred Chou <[email protected]>
>
> The temporary buffer to hold firmware data is not really needed,
> and memcpy can be avoided by using data pointer instead.
>
> Signed-off-by: Fred Chou <[email protected]>
> ---
> drivers/net/wireless/ath/ath9k/hif_usb.c | 12 ++----------
> 1 file changed, 2 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
> index 10c02f5..0bc35a8 100644
> --- a/drivers/net/wireless/ath/ath9k/hif_usb.c
> +++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
> @@ -986,30 +986,22 @@ static int ath9k_hif_usb_download_fw(struct hif_device_usb *hif_dev)
> const void *data = hif_dev->fw_data;

Here data can be vmalloc() backed.

> size_t len = hif_dev->fw_size;
> u32 addr = AR9271_FIRMWARE;
> - u8 *buf = kzalloc(4096, GFP_KERNEL);

Here buf is kmalloc() backed.

> u32 firm_offset;
>
> - if (!buf)
> - return -ENOMEM;
> -
> while (len) {
> transfer = min_t(size_t, len, 4096);
> - memcpy(buf, data, transfer);
>
> err = usb_control_msg(hif_dev->udev,
> usb_sndctrlpipe(hif_dev->udev, 0),
> FIRMWARE_DOWNLOAD, 0x40 | USB_DIR_OUT,
> - addr >> 8, 0, buf, transfer, HZ);


Are you sure usb_control_msg() accepts vmalloc()ed buffers ?

My guess is the answer is no.

2015-03-03 14:41:00

by Fred Chou

Subject: Re: [PATCH] ath9k_htc: avoid memcpy when downloading firmware

On 3/3/2015 2:00 PM, Eric Dumazet wrote:
> On Tue, 2015-03-03 at 12:24 +0800, Fred Chou wrote:
>> From: Fred Chou <[email protected]>
>>
>> The temporary buffer to hold firmware data is not really needed,
>> and memcpy can be avoided by using data pointer instead.
>>
>> Signed-off-by: Fred Chou <[email protected]>
>> ---
>> drivers/net/wireless/ath/ath9k/hif_usb.c | 12 ++----------
>> 1 file changed, 2 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
>> index 10c02f5..0bc35a8 100644
>> --- a/drivers/net/wireless/ath/ath9k/hif_usb.c
>> +++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
>> @@ -986,30 +986,22 @@ static int ath9k_hif_usb_download_fw(struct hif_device_usb *hif_dev)
>> const void *data = hif_dev->fw_data;
>
> Here data can be vmalloc() backed.
>
>> size_t len = hif_dev->fw_size;
>> u32 addr = AR9271_FIRMWARE;
>> - u8 *buf = kzalloc(4096, GFP_KERNEL);
>
> Here buf is kmalloc() backed.
>
>> u32 firm_offset;
>>
>> - if (!buf)
>> - return -ENOMEM;
>> -
>> while (len) {
>> transfer = min_t(size_t, len, 4096);
>> - memcpy(buf, data, transfer);
>>
>> err = usb_control_msg(hif_dev->udev,
>> usb_sndctrlpipe(hif_dev->udev, 0),
>> FIRMWARE_DOWNLOAD, 0x40 | USB_DIR_OUT,
>> - addr >> 8, 0, buf, transfer, HZ);
>
>
> Are you sure usb_control_msg() accepts vmalloc()ed buffers ?
>
> My guess is the answer is no.
>
>

I agree, and I would like to drop the patch. Thanks.

2015-03-03 14:43:30

by Kalle Valo

Subject: Re: [PATCH] ath9k_htc: avoid memcpy when downloading firmware

Fred Chou <[email protected]> writes:

>> Are you sure usb_control_msg() accepts vmalloc()ed buffers ?
>>
>> My guess is the answer is no.
>>
>>
>
> I agree, and I would like to drop the patch. Thanks.

I dropped it from my queue.

--
Kalle Valo