Hello, On Sat, Jun 03, 2017 at 12:01:24PM +0200, rolf.freitag@xxxxxxxx wrote: > Hi, > > compiling cyclictest gives 4 warnings of type > > warning: ignoring return value of 'write' > > and three of type > > warning: ... may be used uninitialized in this function > > So i eleminated the first sort with a trash variable, which adds up > the return values and recycles them (their entropy) at the end via > srand(). This also avoids a write-only variable. > I eleminated the second sort by initializing the variables. > > --- a/src/cyclictest/cyclictest.c > +++ b/src/cyclictest/cyclictest.c > @@ -222,6 +222,7 @@ static int use_fifo = 0; > static pthread_t fifo_threadid; > static int laptop = 0; > static int use_histfile = 0; > +static unsigned int trash; // for unused return values, to avoid compiler warnings because of ignored return values What is the good reason to collect these in a global variable? Ah, later in the patch you use it for srand. Is this a good idea? If so, document it here. Oh, and AFAIK cyclictest uses C comments, not C++. > #ifdef ARCH_HAS_SMI_COUNTER > static int smi = 0; > @@ -491,10 +492,10 @@ static void tracemark(char *fmt, ...) > va_end(ap); > > /* write the tracemark message */ > - write(tracemark_fd, tracebuf, len); > + trash += write(tracemark_fd, tracebuf, len); IMHO that's not very sensible. The compiler tells you, that you ignore the return value of write and that might be a bad thing. So the (more) sensible options are: - add proper error checking and let (here) tracemark fail if the write fails (and retry if the return value is positive but less than len). - you don't care about the return value, so use: (void)write(tracemark_fd, tracebuf, len) - keep the warnings until someone else fixes them properly. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
