[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] libxc/pm: Fix NULL pointer checks.
>>> On 10.09.13 at 14:48, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote: > On Tue, 2013-09-10 at 13:23 +0100, Jan Beulich wrote: >> >>> On 10.09.13 at 11:29, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote: >> > --- a/tools/libxc/xc_pm.c >> > +++ b/tools/libxc/xc_pm.c >> > @@ -285,7 +285,7 @@ int xc_set_cpufreq_gov(xc_interface *xch, int cpuid, > char *govname) >> > DECLARE_SYSCTL; >> > char *scaling_governor = sysctl.u.pm_op.u.set_gov.scaling_governor; >> > >> > - if ( (xch < 0) || (!govname) ) >> > + if ( !xch || !govname ) >> >> I'm very surprised the compiler didn't reject this - I'm unaware of >> an extension that would allow pointers to be compared by other >> than == and != (plus it's all but clear what e.g. a "negative" >> pointer really is). > > We were just discussing this at lunch and couldn't work it out either, > but indeed both gcc 4.7.[23] and clang 3.2 accept this when building > with -Wall: > int main(int argc, char **argv) > { > if ( argv[1] < 0 ) > printf("ARGV[1] < 0\n"); > else > printf("ARGV[1] >= 0\n"); > return 0; > } Right. The warning is hidden behind -Wextra (i.e. there's no more specific flag controlling this), and there's no way to turn off that behavior altogether. Odd, but I guess we have to live with it (entering this as a bug would just produce another of the many orphaned entries in their bugzilla I'm afraid). Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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