Re: [PATCH v14 02/12] powerpc/irq: use memblock functions returning virtual address

On Thu, Jan 24, 2019 at 04:51:53PM +0000, Mark Rutland wrote:

On Thu, Jan 24, 2019 at 04:19:33PM +0000, Christophe Leroy wrote:

quoted

Since only the virtual address of allocated blocks is used,
lets use functions returning directly virtual address.

Those functions have the advantage of also zeroing the block.

Suggested-by: Mike Rapoport <redacted>
Acked-by: Mike Rapoport <redacted>
Signed-off-by: Christophe Leroy <redacted>

[...]

quoted

+static void *__init alloc_stack(void)
+{
+	void *ptr = memblock_alloc(THREAD_SIZE, THREAD_SIZE);
+
+	if (!ptr)
+		panic("cannot allocate stacks");
+
+	return ptr;
+}

I believe memblock_alloc() will panic() if it cannot allocate memory,
since that goes:

 memblock_alloc()
 -> memblock_alloc_try_nid()
    -> panic()

So you can get rid of the panic() here, or if you want a custom panic
message, you can use memblock_alloc_nopanic().

As we've already discussed it in [1], I'm working on removing the
_nopanic() versions and dropping the panic() calls from memblock_alloc()
and friends.

I've posted v2 of the patches earlier this week [2].
 

[...]

[1] https://lore.kernel.org/lkml/20190108143428.GB14063@rapoport-lnx/ (local) 
[2] https://lore.kernel.org/lkml/1548057848-15136-1-git-send-email-rppt@linux.ibm.com/ (local)

quoted

 static void *__init alloc_stack(unsigned long limit, int cpu)
 {
-	unsigned long pa;
+	void *ptr;
 
 	BUILD_BUG_ON(STACK_INT_FRAME_SIZE % 16);
 
-	pa = memblock_alloc_base_nid(THREAD_SIZE, THREAD_SIZE, limit,
-					early_cpu_to_node(cpu), MEMBLOCK_NONE);
-	if (!pa) {
-		pa = memblock_alloc_base(THREAD_SIZE, THREAD_SIZE, limit);
-		if (!pa)
-			panic("cannot allocate stacks");
-	}
+	ptr = memblock_alloc_try_nid(THREAD_SIZE, THREAD_SIZE,
+				     MEMBLOCK_LOW_LIMIT, limit,
+				     early_cpu_to_node(cpu));
+	if (!ptr)
+		panic("cannot allocate stacks");

The same applies here -- memblock_alloc_try_nid() will panic itself
rather than returning NULL.

Otherwise, this looks like a nice cleanup. With the panics removed (or
using the _nopanic() allocators), feel free to add:

Acked-by: Mark Rutland <mark.rutland@arm.com>

Thanks,
Mark.

-- 
Sincerely yours,
Mike.