On Thu, Feb 07, 2019 at 05:59:48PM +1100, Andrew Donnellan wrote: > On 7/2/19 5:37 pm, Segher Boessenkool wrote: > >On Thu, Feb 07, 2019 at 04:33:23PM +1100, Andrew Donnellan wrote: > >>Some older gccs (<GCC 7), when invoked with -fsanitize-coverage=trace-pc, > >>cause a spurious uninitialised variable warning in dt_cpu_ftrs.c: > >> > >> arch/powerpc/kernel/dt_cpu_ftrs.c: In function > >> ‘cpufeatures_process_feature’: > >> arch/powerpc/kernel/dt_cpu_ftrs.c:686:7: warning: ‘m’ may be used > >> uninitialized in this function [-Wmaybe-uninitialized] > >> if (m->cpu_ftr_bit_mask) > > > >It seems to me the warning is correct? If enable_unknown is false and no > >cpu_feature is found, it will in > > > > if (m->cpu_ftr_bit_mask) > > cur_cpu_spec->cpu_features |= m->cpu_ftr_bit_mask; > > > >enable random features (whatever was last in the table), or indeed access > >via NULL if the table is length 0? So maybe this should be > > > > if (known && m->cpu_ftr_bit_mask) > > cur_cpu_spec->cpu_features |= m->cpu_ftr_bit_mask; > > > >instead? (The code would be much clearer if all the known vs. !known > >codepath was fully separated here). > > The table is never length 0, it's a statically defined array.
Sure, and presumably that is why newer GCC doesn't warn. But what about the other point? Is this code ever correct? Enabling random features (in cur_cpu_spec->cpu_features) when the name isn't found seems wrong. Segher
