* [PATCH] usb: renesas_usbhs: Use struct assignment instead of memcpy()
@ 2019-06-13 11:18 Yoshihiro Shimoda
2019-06-17 8:40 ` Simon Horman
2019-06-18 5:59 ` Greg KH
0 siblings, 2 replies; 5+ messages in thread
From: Yoshihiro Shimoda @ 2019-06-13 11:18 UTC (permalink / raw)
To: gregkh; +Cc: linux-usb, linux-renesas-soc, Yoshihiro Shimoda
To avoid the error-proneness of calls to sizeof() in the memcpy,
this patch uses struct assignment instead of memcpy.
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
---
This patch is based on Greg's linux-usb.git / usb-next branch.
Note that mod_host.c also has memcpy but we cannot use struct assignment
for it because the type of urb->setup_patcket is just "unsigned char *".
drivers/usb/renesas_usbhs/common.c | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)
diff --git a/drivers/usb/renesas_usbhs/common.c b/drivers/usb/renesas_usbhs/common.c
index a501ea6..ebbe322 100644
--- a/drivers/usb/renesas_usbhs/common.c
+++ b/drivers/usb/renesas_usbhs/common.c
@@ -651,9 +651,8 @@ static struct renesas_usbhs_platform_info *usbhs_parse_dt(struct device *dev)
return NULL;
dparam = &info->driver_param;
- memcpy(dparam, &data->param, sizeof(data->param));
- memcpy(&info->platform_callback, data->platform_callback,
- sizeof(*data->platform_callback));
+ *dparam = data->param;
+ info->platform_callback = *data->platform_callback;
if (!of_property_read_u32(dev->of_node, "renesas,buswait", &tmp))
dparam->buswait_bwait = tmp;
@@ -714,17 +713,13 @@ static int usbhs_probe(struct platform_device *pdev)
* care platform info
*/
- memcpy(&priv->dparam,
- &info->driver_param,
- sizeof(struct renesas_usbhs_driver_param));
+ priv->dparam = info->driver_param;
if (!info->platform_callback.get_id) {
dev_err(&pdev->dev, "no platform callbacks");
return -EINVAL;
}
- memcpy(&priv->pfunc,
- &info->platform_callback,
- sizeof(struct renesas_usbhs_platform_callback));
+ priv->pfunc = info->platform_callback;
/* set driver callback functions for platform */
dfunc = &info->driver_callback;
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] usb: renesas_usbhs: Use struct assignment instead of memcpy()
2019-06-13 11:18 [PATCH] usb: renesas_usbhs: Use struct assignment instead of memcpy() Yoshihiro Shimoda
@ 2019-06-17 8:40 ` Simon Horman
2019-06-18 5:59 ` Greg KH
1 sibling, 0 replies; 5+ messages in thread
From: Simon Horman @ 2019-06-17 8:40 UTC (permalink / raw)
To: Yoshihiro Shimoda; +Cc: gregkh, linux-usb, linux-renesas-soc
On Thu, Jun 13, 2019 at 08:18:48PM +0900, Yoshihiro Shimoda wrote:
> To avoid the error-proneness of calls to sizeof() in the memcpy,
> this patch uses struct assignment instead of memcpy.
>
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] usb: renesas_usbhs: Use struct assignment instead of memcpy()
2019-06-13 11:18 [PATCH] usb: renesas_usbhs: Use struct assignment instead of memcpy() Yoshihiro Shimoda
2019-06-17 8:40 ` Simon Horman
@ 2019-06-18 5:59 ` Greg KH
2019-06-18 7:26 ` Geert Uytterhoeven
2019-06-18 8:42 ` Yoshihiro Shimoda
1 sibling, 2 replies; 5+ messages in thread
From: Greg KH @ 2019-06-18 5:59 UTC (permalink / raw)
To: Yoshihiro Shimoda; +Cc: linux-usb, linux-renesas-soc
On Thu, Jun 13, 2019 at 08:18:48PM +0900, Yoshihiro Shimoda wrote:
> To avoid the error-proneness of calls to sizeof() in the memcpy,
> this patch uses struct assignment instead of memcpy.
>
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> ---
> This patch is based on Greg's linux-usb.git / usb-next branch.
> Note that mod_host.c also has memcpy but we cannot use struct assignment
> for it because the type of urb->setup_patcket is just "unsigned char *".
>
> drivers/usb/renesas_usbhs/common.c | 13 ++++---------
> 1 file changed, 4 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/usb/renesas_usbhs/common.c b/drivers/usb/renesas_usbhs/common.c
> index a501ea6..ebbe322 100644
> --- a/drivers/usb/renesas_usbhs/common.c
> +++ b/drivers/usb/renesas_usbhs/common.c
> @@ -651,9 +651,8 @@ static struct renesas_usbhs_platform_info *usbhs_parse_dt(struct device *dev)
> return NULL;
>
> dparam = &info->driver_param;
> - memcpy(dparam, &data->param, sizeof(data->param));
> - memcpy(&info->platform_callback, data->platform_callback,
> - sizeof(*data->platform_callback));
> + *dparam = data->param;
> + info->platform_callback = *data->platform_callback;
How are the original calls here "error-prone"? Yes, the compiler will
end up calling memcpy somehow with this change, but it feels "wrong" to
hide a memory copy like this.
So are you _sure_ you want this change?
thanks,
greg k-h
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] usb: renesas_usbhs: Use struct assignment instead of memcpy()
2019-06-18 5:59 ` Greg KH
@ 2019-06-18 7:26 ` Geert Uytterhoeven
2019-06-18 8:42 ` Yoshihiro Shimoda
1 sibling, 0 replies; 5+ messages in thread
From: Geert Uytterhoeven @ 2019-06-18 7:26 UTC (permalink / raw)
To: Greg KH; +Cc: Yoshihiro Shimoda, USB list, Linux-Renesas
Hi Greg,
On Tue, Jun 18, 2019 at 9:17 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> On Thu, Jun 13, 2019 at 08:18:48PM +0900, Yoshihiro Shimoda wrote:
> > To avoid the error-proneness of calls to sizeof() in the memcpy,
> > this patch uses struct assignment instead of memcpy.
> >
> > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> > ---
> > This patch is based on Greg's linux-usb.git / usb-next branch.
> > Note that mod_host.c also has memcpy but we cannot use struct assignment
> > for it because the type of urb->setup_patcket is just "unsigned char *".
> >
> > drivers/usb/renesas_usbhs/common.c | 13 ++++---------
> > 1 file changed, 4 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/usb/renesas_usbhs/common.c b/drivers/usb/renesas_usbhs/common.c
> > index a501ea6..ebbe322 100644
> > --- a/drivers/usb/renesas_usbhs/common.c
> > +++ b/drivers/usb/renesas_usbhs/common.c
> > @@ -651,9 +651,8 @@ static struct renesas_usbhs_platform_info *usbhs_parse_dt(struct device *dev)
> > return NULL;
> >
> > dparam = &info->driver_param;
> > - memcpy(dparam, &data->param, sizeof(data->param));
> > - memcpy(&info->platform_callback, data->platform_callback,
> > - sizeof(*data->platform_callback));
> > + *dparam = data->param;
> > + info->platform_callback = *data->platform_callback;
>
> How are the original calls here "error-prone"? Yes, the compiler will
> end up calling memcpy somehow with this change, but it feels "wrong" to
> hide a memory copy like this.
There are no checks that:
- the source and destination pointers point to the same type,
- the passed size matches the actual object size.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 5+ messages in thread
* RE: [PATCH] usb: renesas_usbhs: Use struct assignment instead of memcpy()
2019-06-18 5:59 ` Greg KH
2019-06-18 7:26 ` Geert Uytterhoeven
@ 2019-06-18 8:42 ` Yoshihiro Shimoda
1 sibling, 0 replies; 5+ messages in thread
From: Yoshihiro Shimoda @ 2019-06-18 8:42 UTC (permalink / raw)
To: Greg KH; +Cc: linux-usb, linux-renesas-soc
Hi Greg,
> From: Greg KH, Sent: Tuesday, June 18, 2019 2:59 PM
>
> On Thu, Jun 13, 2019 at 08:18:48PM +0900, Yoshihiro Shimoda wrote:
> > To avoid the error-proneness of calls to sizeof() in the memcpy,
> > this patch uses struct assignment instead of memcpy.
> >
> > Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> > ---
> > This patch is based on Greg's linux-usb.git / usb-next branch.
> > Note that mod_host.c also has memcpy but we cannot use struct assignment
> > for it because the type of urb->setup_patcket is just "unsigned char *".
> >
> > drivers/usb/renesas_usbhs/common.c | 13 ++++---------
> > 1 file changed, 4 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/usb/renesas_usbhs/common.c b/drivers/usb/renesas_usbhs/common.c
> > index a501ea6..ebbe322 100644
> > --- a/drivers/usb/renesas_usbhs/common.c
> > +++ b/drivers/usb/renesas_usbhs/common.c
> > @@ -651,9 +651,8 @@ static struct renesas_usbhs_platform_info *usbhs_parse_dt(struct device *dev)
> > return NULL;
> >
> > dparam = &info->driver_param;
> > - memcpy(dparam, &data->param, sizeof(data->param));
> > - memcpy(&info->platform_callback, data->platform_callback,
> > - sizeof(*data->platform_callback));
> > + *dparam = data->param;
> > + info->platform_callback = *data->platform_callback;
>
> How are the original calls here "error-prone"?
When I was developing the patch above [1], I had actually confused
about these arguments of memcpy...
[1]
https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git/commit/drivers/usb/renesas_usbhs?h=usb-next&id=be21a02a5a5ec88b12ce535ead715d4bbb173a55
I think this is because object and pointer members are mixed in these structures.
So, as I mentioned on the following email [2], I should try to simplify the code
instead of this patch.
[2]
https://marc.info/?l=linux-usb&m=155748940717665&w=2
> So are you _sure_ you want this change?
I'm sorry, I would like to drop this patch.
Best regards,
Yoshihiro Shimoda
> thanks,
>
> greg k-h
^ permalink raw reply [flat|nested] 5+ messages in thread
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2019-06-13 11:18 [PATCH] usb: renesas_usbhs: Use struct assignment instead of memcpy() Yoshihiro Shimoda
2019-06-17 8:40 ` Simon Horman
2019-06-18 5:59 ` Greg KH
2019-06-18 7:26 ` Geert Uytterhoeven
2019-06-18 8:42 ` Yoshihiro Shimoda
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