Hi Joe, On Wed, Jun 05, 2019 at 07:28:53PM -0700, Joe Perches wrote: > On Thu, 2019-06-06 at 09:08 +0800, Kefeng Wang wrote: > > On 2019/6/5 22:42, Pali Rohár wrote: > > > On Wednesday 05 June 2019 22:24:28 Kefeng Wang wrote: > > > > IS_ERR(_OR_NULL) already contain an 'unlikely' compiler flag, > > > > so no need to do that again from its callers. Drop it. > > > Hi! I already reviewed this patch and rejected it, see: > > > https://patchwork.kernel.org/patch/10817475/ > > OK, please ignore it. > > I think the stated reason of better readability isn't > particularly sensible as the object code produced is > actually slightly larger. > > x86-64 defconfig (gcc 8.3.0) > > $ size drivers/input/mouse/alps.o* > text data bss dec hex filename > 29416 56 0 29472 7320 drivers/input/mouse/alps.o.new > 29432 56 0 29488 7330 drivers/input/mouse/alps.o.old If gcc produces worse code for double unlikely, you should probably report it to gcc folks, no? Or double unlikely turns into likely? > > Also if this unlikely is _really_ useful, perhaps the > !IS_ERR immediately after could also use likely as the > test seems only done for an OOM condition. No, once you take the IS_ERR_OR_NULL(priv->dev3) == true branch it stops being hot path and additional annotations are completely unneeded. And if we failed to create and register priv->dev3 device - that's an error and system is degraded. Can't do much here. Thanks. -- Dmitry
