On Wed, 24 May 2017, Doug Anderson wrote: > * Matthias has been sending out individual patches that take each > particular case into account to try to remove the warnings. In some > cases this removes totally dead code. In other cases this adds > __maybe_unused. ...and as a last resort it uses #ifdef. In each of > these individual patches we wouldn't want a list of all other patches, > I think. >
Again, I defer to maintainers like Andrew and Ingo who have to deal with an enormous amount of patches on how they would like to handle it; I don't think myself or anybody else who doesn't deal with a large number of patches should be mandating how it's handled. For reference, the patchset that this patch originated from added 8 lines and removed 1, so I disagree that this cleans anything up; in reality, it obfuscates the code and makes the #ifdef nesting more complex. > If you just want a list of things in response to this thread... > > Clang's behavior has found some dead code, as shown by: > > * https://patchwork.kernel.org/patch/9732161/ > ring-buffer: Remove unused function __rb_data_page_index() > * https://patchwork.kernel.org/patch/9735027/ > r8152: Remove unused function usb_ocp_read() > * https://patchwork.kernel.org/patch/9735053/ > net1080: Remove unused function nc_dump_ttl() > * https://patchwork.kernel.org/patch/9741513/ > crypto: rng: Remove unused function __crypto_rng_cast() > * https://patchwork.kernel.org/patch/9741539/ > x86/ioapic: Remove unused function IO_APIC_irq_trigger() > * https://patchwork.kernel.org/patch/9741549/ > ASoC: Intel: sst: Remove unused function sst_restore_shim64() > * https://patchwork.kernel.org/patch/9743225/ > ASoC: cht_bsw_max98090_ti: Remove unused function cht_get_codec_dai() > > ...plus more examples... > Let us please not confuse the matter by suggesting that you cannot continue to do this work by simply removing the __attribute__((unused)) and emailing kernel-janitors to cleanup unused code (which should already be significantly small by the sheer fact that it is inlined). > However, clang's behavior has also led to patches that add a > "__maybe_unused" attribute (usually no increase in LOC unless it > causes word wrap) and also added a handful of #ifdefs, as you've > pointed out. The example we already talked about was: > The good work to remove truly dead code may easily continue while not adding more and more LOC to suppress these warnings for a compiler that is very heavily in the minority.
