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[24.205.208.113]) by smtp.gmail.com with ESMTPSA id o21-20020ac85a55000000b002e16389b501sm8462867qta.96.2022.03.12.15.48.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 12 Mar 2022 15:48:41 -0800 (PST) Subject: Re: [PATCH] media: stkwebcam: move stk_camera_read_reg() scratch buffer to struct stk_camera To: Pavel Skripkin , mchehab@kernel.org, hverkuil-cisco@xs4all.nl, cai.huoqing@linux.dev, xose.vazquez@gmail.com Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org References: <20220312173049.1410977-1-trix@redhat.com> <65a1d178-8511-a023-2655-94540114086c@gmail.com> From: Tom Rix Message-ID: Date: Sat, 12 Mar 2022 15:48:39 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <65a1d178-8511-a023-2655-94540114086c@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/12/22 11:58 AM, Pavel Skripkin wrote: > On 3/12/22 20:30, trix@redhat.com wrote: >> From: Tom Rix >> >> In stk_camera_read_reg() a single byte buffer is alloc-ed and >> freed on every function call.  Since the size is known, >> move the buffer to the struct stk_camera where it will be alloc-ed >> and freed once. >> >> Signed-off-by: Tom Rix >> --- >>   drivers/media/usb/stkwebcam/stk-webcam.c | 11 ++--------- >>   drivers/media/usb/stkwebcam/stk-webcam.h |  2 ++ >>   2 files changed, 4 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/media/usb/stkwebcam/stk-webcam.c >> b/drivers/media/usb/stkwebcam/stk-webcam.c >> index 5b822214ccc5c..787edb3d47c23 100644 >> --- a/drivers/media/usb/stkwebcam/stk-webcam.c >> +++ b/drivers/media/usb/stkwebcam/stk-webcam.c >> @@ -150,25 +150,18 @@ int stk_camera_write_reg(struct stk_camera >> *dev, u16 index, u8 value) >>   int stk_camera_read_reg(struct stk_camera *dev, u16 index, u8 *value) > > And just random note: there are 4 possible uninit value bugs. > > stk_start_stream() calls stk_camera_read_reg 4 times, but ignores > return values. > > stk_camera_read_reg() should have __must_check annotation and return > value should be checked on each call. > > > If you have time you can take care of it :) Or I will fix it one day... These do show up in my usual static analysis and it why I was looking at this file. And was sidetracked by the short malloc. Unfortunately I looked and there are many other similar instances treewide ~100 These aren't caught in checkpatch, so working on that.. Tom > > > > > > With regards, > Pavel Skripkin >