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.