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

From: Palmer Dabbelt
Date: Mon Aug 20 2018 - 19:30:46 EST

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;

/* 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);
+ flush_icache_all();


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.