On Thu, 25 Aug 2022, David Hildenbrand [off-list ref] wrote:

On 24.08.22 18:52, Joe Perches wrote:

quoted

On Wed, 2022-08-24 at 18:31 +0200, David Hildenbrand wrote:

quoted

checkpatch does not point out that VM_BUG_ON() and friends should be
avoided, however, Linus notes:

    VM_BUG_ON() has the exact same semantics as BUG_ON. It is literally
    no different, the only difference is "we can make the code smaller
    because these are less important". [1]

So let's warn on VM_BUG_ON() and friends as well. While at it, make it
clearer that the kernel really shouldn't be crashed.

Note that there are some other *_BUG_ON flavors, but they are not all
bad: for example, KVM_BUG_ON() only triggers a WARN_ON_ONCE and then
flags KVM as being buggy, so we'll not care about them for now here.

[]

quoted

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl

[]

quoted

@@ -4695,12 +4695,12 @@ sub process {
 			}
 		}
 
-# avoid BUG() or BUG_ON()
-		if ($line =~ /\b(?:BUG|BUG_ON)\b/) {
+# do not use BUG(), BUG_ON(), VM_BUG_ON() and friends.
+		if ($line =~ /\b(?:BUG|BUG_ON|VM_BUG_ON|VM_BUG_ON_[A-Z]+)\b/) {

Perhaps better as something like the below to pick up more variants

Trying to find more possible variants and exceptions

CI_BUG_ON(
-> Bad with CONFIG_DRM_I915_DEBUG
GEM_BUG_ON(
-> Bad with CONFIG_DRM_I915_DEBUG_GEM_ONCE

These are hidden behind debug knobs that we use in our CI to
specifically catch "should not happen" cases fast and loud. Should not
be a problem for regular users.

BR,
Jani.

So an extended versions of your proposal like (ignoring do_BUG and handle_BUG, people are smart enough to figure that out)

if ($line =~ /\b(?!AA_|BUILD_|DCCP_|IDA_|KVM_|RWLOCK_|snd_|SPIN_)(?:[a-zA-Z_]*_)?BUG(?:_ON)?(?:_[A-Z_]+)?\s*\(/

?

-- 
Jani Nikula, Intel Open Source Graphics Center