Re: [PATCH v3 1/2] RISC-V: Define sys_riscv_flush_icache when SMP=n

[Palmer Dabbelt]

On Tue, 14 Aug 2018 06:39:23 PDT (-0700), Christoph Hellwig wrote:
> >  SYSCALL_DEFINE3(riscv_flush_icache, uintptr_t, start, uintptr_t, end,
> >  	uintptr_t, flags)
> >  {
> > +#ifdef CONFIG_SMP
> >  	struct mm_struct *mm = current->mm;
> >  	bool local = (flags & SYS_RISCV_FLUSH_ICACHE_LOCAL) != 0;
> > +#endif
> >
> >  	/* Check the reserved flags. */
> >  	if (unlikely(flags & ~SYS_RISCV_FLUSH_ICACHE_ALL))
> >  		return -EINVAL;
> >
> > +	/*
> > +	 * Without CONFIG_SMP flush_icache_mm is a just a flush_icache_all(),
> > +	 * which generates unused variable warnings all over this function.
> > +	 */
> > +#ifdef CONFIG_SMP
> >  	flush_icache_mm(mm, local);
> > +#else
> > +	flush_icache_all();
> > +#endif
>
> Eeek.
>
> Something like an unconditional:
>
> 	flush_icache_mm(current->mm, flags & SYS_RISCV_FLUSH_ICACHE_LOCAL);
>
> should solve those issues.
>
> Also in the longer run we should turn the !SMP flush_icache_mm stub
> into an inline function to solve this problem for all potential
> callers.  Excepte that flush_icache_mm happens to be a RISC-V specific
> API without any other callers.  So for now I think the above is what
> I'd do, but this area has a lot of room for cleanup.

Thanks, that's a lot cleaner.  I missed this for the PR, but I'll submit a 
cleanup patch after RC1.