Return-path: Received: from mail-pa0-f41.google.com ([209.85.220.41]:35109 "EHLO mail-pa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755752AbbCCOlA (ORCPT ); Tue, 3 Mar 2015 09:41:00 -0500 Message-ID: <54F5C813.4030505@gmail.com> (sfid-20150303_154128_013572_0AB8C45C) Date: Tue, 03 Mar 2015 22:41:23 +0800 From: Fred Chou MIME-Version: 1.0 To: Eric Dumazet CC: ath9k-devel@qca.qualcomm.com, kvalo@codeaurora.org, linux-wireless@vger.kernel.org, ath9k-devel@lists.ath9k.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ath9k_htc: avoid memcpy when downloading firmware References: <1425356643-2707-1-git-send-email-fred.chou.nd@gmail.com> <1425362407.5130.161.camel@edumazet-glaptop2.roam.corp.google.com> In-Reply-To: <1425362407.5130.161.camel@edumazet-glaptop2.roam.corp.google.com> Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: 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 >> >> 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 >> --- >> 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.