Hi, Roger Quadros <rogerq@xxxxxx> writes: > On 06/04/17 13:45, Felipe Balbi wrote: >> >> Hi, >> >> Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx> writes: >>> Hello. >>> >>> On 4/6/2017 1:17 PM, Felipe Balbi wrote: >>> >>>> From: Roger Quadros <rogerq@xxxxxx> >>>> >>>> We must make sure that our macros are safe against expressions passed >>>> as arguments. We have see one problem where GTXFIFOSIZ(n) was failling >>> >>> "Seen" and "failing". >>> >>>> when passed the expression (epnum >> 1) as argument. The problem was >>>> caused by operator precedence between >> and *. >>>> >>>> To make sure macros are safe, we just wrap argument with () when using >>>> it. >>>> >>>> Signed-off-by: Roger Quadros <rogerq@xxxxxx> >>>> Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx> >>>> --- >>>> >>>> As discussed over IRC, Roger figured out what was the problem >>>> with "Bryan's patch". It turns out that GTXFIFOSIZ() macro wasn't >>>> safe against expression arguments. >>>> >>>> Roger provided a patch, which I'm now sending to linux-usb in his >>>> regard. >>>> >>>> drivers/usb/dwc3/core.h | 26 +++++++++++++------------- >>>> 1 file changed, 13 insertions(+), 13 deletions(-) >>>> >>>> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h >>>> index 459ecf3afa48..8a0fbcd99638 100644 >>>> --- a/drivers/usb/dwc3/core.h >>>> +++ b/drivers/usb/dwc3/core.h >>> [...] >>>> @@ -460,7 +460,7 @@ >>>> #define DWC3_DEPCMD_CMD(x) ((x) & 0xf) >>>> >>>> /* The EP number goes 0..31 so ep0 is always out and ep1 is always in */ >>>> -#define DWC3_DALEPENA_EP(n) BIT(n) >>>> +#define DWC3_DALEPENA_EP(n) BIT((n)) >>> >>> Why do we need double parens? >> >> I don't know (i.e. don't wanna care) how BIT() is implemented. But I >> still want to be able to: >> >> DWC3_DALEPENA_EP(dwc->num_eps - (dep->epnum >> 1) + whatever_number_I_want); >> > > Caller needs to assume that macro is sane so I'd avoid the double parens. > > fyi. > #define BIT(nr) (1UL << (nr)) fair enough, fixed on 'next' and 'testing/next' -- balbi -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
