Re: [PATCH] btrfs: Fix a C compliance issue

On Sat, Jun 16, 2018 at 01:28:13PM +0300, Nikolay Borisov wrote:

On 16.06.2018 01:36, Bart Van Assche wrote:

quoted

The C programming language does not allow to use preprocessor statements
inside macro arguments (pr_info() is defined as a macro). Hence rework
the pr_info() statement in btrfs_print_mod_info() such that it becomes
compliant. This patch allows tools like sparse to analyze the BTRFS
source code.

Fixes: 62e855771dac ("btrfs: convert printk(KERN_* to use pr_* calls")
Signed-off-by: Bart Van Assche <redacted>
Cc: Jeff Mahoney <redacted>
Cc: David Sterba <dsterba@suse.com>
---
 fs/btrfs/super.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 81107ad49f3a..dd4980df5b8e 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c

@@ -2369,7 +2369,7 @@ static __cold void btrfs_interface_exit(void)
 
 static void __init btrfs_print_mod_info(void)
 {
-	pr_info("Btrfs loaded, crc32c=%s"
+	static const char fmt[] = KERN_INFO "Btrfs loaded, crc32c=%s"
 #ifdef CONFIG_BTRFS_DEBUG
 			", debug=on"
 #endif

@@ -2382,8 +2382,8 @@ static void __init btrfs_print_mod_info(void)
 #ifdef CONFIG_BTRFS_FS_REF_VERIFY
 			", ref-verify=on"
 #endif
-			"\n",
-			crc32c_impl());
+			"\n";
+	printk(fmt, crc32c_impl());

I'd rather not see more printk being added. Nothing prevents from having
the fmt string being passed to pr_info.

So you mean to do

+	static const char fmt[] = "Btrfs loaded, crc32c=%s"
+	pr_info(fmt);

?