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)) cheers, -roger -- 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
