Re: [PATCH v3 09/17] memblock: make memblock_debug and related functionality private

[Andrew Morton]

On Tue, 18 Aug 2020 18:16:26 +0300 Mike Rapoport <rppt@xxxxxxxxxx> wrote:

> From: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> 
> The only user of memblock_dbg() outside memblock was s390 setup code and it
> is converted to use pr_debug() instead.
> This allows to stop exposing memblock_debug and memblock_dbg() to the rest
> of the kernel.
> 
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -137,7 +137,10 @@ struct memblock_type physmem = {
>  	     i < memblock_type->cnt;					\
>  	     i++, rgn = &memblock_type->regions[i])
>  
> -int memblock_debug __initdata_memblock;
> +#define memblock_dbg(fmt, ...) \
> +	if (memblock_debug) printk(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
> +

checkpatch doesn't like this much.

ERROR: Macros starting with if should be enclosed by a do - while loop to avoid possible if/else logic defects
#101: FILE: mm/memblock.c:140:
+#define memblock_dbg(fmt, ...) \
+	if (memblock_debug) printk(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)

WARNING: Prefer [subsystem eg: netdev]_info([subsystem]dev, ... then dev_info(dev, ... then pr_info(...  to printk(KERN_INFO ...
#102: FILE: mm/memblock.c:141:
+	if (memblock_debug) printk(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)

ERROR: trailing statements should be on next line
#102: FILE: mm/memblock.c:141:
+	if (memblock_debug) printk(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)


The first one is significant:

	if (foo)
		memblock_dbg(...);
	else
		save_the_world();

could end up inadvertently destroying the planet.

This?

--- a/mm/memblock.c~memblock-make-memblock_debug-and-related-functionality-private-fix
+++ a/mm/memblock.c
@@ -137,8 +137,11 @@ struct memblock_type physmem = {
 	     i < memblock_type->cnt;					\
 	     i++, rgn = &memblock_type->regions[i])
 
-#define memblock_dbg(fmt, ...) \
-	if (memblock_debug) printk(KERN_INFO pr_fmt(fmt), ##__VA_ARGS__)
+#define memblock_dbg(fmt, ...)						\
+	do {								\
+		if (memblock_debug)					\
+			pr_info(fmt, ##__VA_ARGS__);			\
+	} while (0)
 
 static int memblock_debug __initdata_memblock;
 static bool system_has_some_mirror __initdata_memblock = false;
_