linux-kernel - checkpatch: comparisons with a constant on the left

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Date:   Fri, 11 Oct 2019 10:52:25 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Joe Perches <joe@...ches.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        linux-kernel@...r.kernel.org
Subject: checkpatch: comparisons with a constant on the left

Hi Joe,

I noticed that this code

	#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 18, 0)

triggers checkpatch's warning:

	"WARNING: Comparisons should place the constant on
		  the right side of the test"

Both LINUX_VERSION_CODE and KERNEL_VERSION are constants, so
I'm wondering if it's worth it to improve that check a tiny
bit.

E.g. something utterly trivial:

---
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index cf7543a9d1b2..8a1964c3d9a5 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -4855,6 +4855,7 @@ sub process {
 			my $to = $4;
 			my $newcomp = $comp;
 			if ($lead !~ /(?:$Operators|\.)\s*$/ &&
+			    $to !~ /^KERNEL_VERSION.*/ &&
 			    $to !~ /^(?:Constant|[A-Z_][A-Z0-9_]*)$/ &&
 			    WARN("CONSTANT_COMPARISON",
 				 "Comparisons should place the constant on the right side of the test\n" . $herecurr) &&
---

I'm sure you'll have a better idea.

	-ss