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Tue, 12 Aug 2025 13:06:38 -0700 (PDT) Date: Tue, 12 Aug 2025 16:06:35 -0400 From: Alan Stern To: Thorsten Blum Cc: Greg Kroah-Hartman , linux-usb@vger.kernel.org, usb-storage@lists.one-eyed-alien.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH] usb: storage: realtek_cr: Simplify rts51x_bulk_transport() Message-ID: References: <20250812144358.122154-1-thorsten.blum@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250812144358.122154-1-thorsten.blum@linux.dev> On Tue, Aug 12, 2025 at 04:43:58PM +0200, Thorsten Blum wrote: > Change the function parameter 'buf_len' from 'int' to 'unsigned int' and > only update the local variable 'residue' if needed. > > Update the rts51x_read_status() function signature accordingly. That last part isn't really necessary, is it? It doesn't make the code any clearer, less buggy, or quicker to execute. > Signed-off-by: Thorsten Blum > --- > drivers/usb/storage/realtek_cr.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/drivers/usb/storage/realtek_cr.c b/drivers/usb/storage/realtek_cr.c > index 7dea28c2b8ee..8a4d7c0f2662 100644 > --- a/drivers/usb/storage/realtek_cr.c > +++ b/drivers/usb/storage/realtek_cr.c > @@ -199,7 +199,8 @@ static const struct us_unusual_dev realtek_cr_unusual_dev_list[] = { > #undef UNUSUAL_DEV > > static int rts51x_bulk_transport(struct us_data *us, u8 lun, > - u8 *cmd, int cmd_len, u8 *buf, int buf_len, > + u8 *cmd, int cmd_len, u8 *buf, > + unsigned int buf_len, > enum dma_data_direction dir, int *act_len) > { > struct bulk_cb_wrap *bcb = (struct bulk_cb_wrap *)us->iobuf; > @@ -260,8 +261,8 @@ static int rts51x_bulk_transport(struct us_data *us, u8 lun, > * try to compute the actual residue, based on how much data > * was really transferred and what the device tells us > */ > - if (residue) > - residue = residue < buf_len ? residue : buf_len; > + if (residue > buf_len) > + residue = buf_len; This really has nothing at all to do with whether buf_len is a signed quantity -- it should never be negative. (And I have no idea why the original code includes that test for residue being nonzero.) Much more serious is something you didn't change: Just above these lines it says: residue = bcs->Residue; It should say: residue = le32_to_cpu(bcs->Residue); Alan Stern