On 03/19/2016 05:51 AM, Paul Mackerras wrote: > On Fri, Mar 18, 2016 at 08:23:24PM +0530, Shreyas B Prabhu wrote: >> Hi Paul, >> >> On 03/17/2016 04:45 PM, Paul Mackerras wrote: >>> On Mon, Feb 29, 2016 at 05:52:59PM +0530, Shreyas B. Prabhu wrote: >>>> Before entering any idle state which can result in a state loss >>>> we currently save the context in the stack before entering idle. >>>> Encapsulate these steps in a macro IDLE_STATE_PREP. Move this >>>> and other macros to commonly accessible location. >>> >>> There are two problems with this. First, your new macro does much >>> more than create a stack frame and save some registers. It also >>> messes with interrupts and potentially executes a blr instruction. >>> That is not what people would expect from the name of the macro or the >>> comments around it. It also means that it would be hard to reuse the >>> macro in another place. >>> >>> Secondly, I don't think this change helps readability. Since the >>> macro is only used in one place, it doesn't reduce the total number of >>> lines of code, in fact it increases it slightly. >> >> This patch was in preparation for support for new POWER ISA v3 idle >> states. The idea was to have the common idle preparation steps in a >> macro which be reused while adding support for the new idle states. With >> this context do you think this macro with better comments make sense? > > No, it still does too many disparate things. In particular it's a bad > idea to embed a blr inside a macro unless the name makes it very clear > that the macro can cause a return (e.g. the macro name is > RETURN_IF_<something>). Yours would need to be called > MAKE_STACK_FRAME_AND_SAVE_SPRS_AND_HARD_DISABLE_AND_RETURN_IF_IRQ_OCCURRED > or something. :) >
Ok :) . I'll drop this patch and work this differently. Thanks, Shreyas _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev