Date: Thu, 17 Aug 2006 15:37:16 -0700 From: John-Mark Gurney <gurney_j@resnet.uoregon.edu> To: Tofig Suleymanov <tofik@oxygen.az> Cc: usb@freebsd.org Subject: Re: USB_ATTACH_SETUP macros question Message-ID: <20060817223716.GW99774@funkthat.com> In-Reply-To: <35069.85.132.32.38.1155816624.squirrel@85.132.32.38> References: <35069.85.132.32.38.1155816624.squirrel@85.132.32.38>
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Tofig Suleymanov wrote this message on Thu, Aug 17, 2006 at 17:10 +0500: > is there anybody to explain why do we have infinite loop inside of > USB_ATTACH_SETUP macros inside of usb_port.h ? How does his loop gets > escaped when we use it in some usb driver ? > > #define USB_ATTACH_SETUP \ > do { \ > sc->sc_dev = self; \ > device_set_desc_copy(self, devinfo); \ > device_printf(self, "%s\n", devinfo); \ > } while (0); The real bug here is the extra ; after the while(0) part... because if you use it as such: if (case) USB_ATTACH_SETUP; else somethingelse; you will get a compile error due to the double semicolon... In cases like this, it is also common to have parens after the macro name so that it looks like a function, and not a simple expresion. -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."
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