-useless-if-before-free -l $(lid -knone free) | xargs -0 \
- perl -0x3b -pi -e \
- 's/\bif\s*\(\s*(\S+?)(?:\s*!=\s*NULL)?\s*\)\s+(free\s*\((?:\s*\([^)]+\))?\s*\1\s*\))/$2/s'
-
-# Or, with git:
-git ls-files -z |xargs -0 perl -0x3b -pi -e '...'
+free=xfree
+git grep -l -z "$free *(" \
+ | xargs -0 useless-if-before-free -l --name="$free" \
+ | xargs -0 perl -0x3b -pi -e \
+ 's/\bif\s*\(\s*(\S+?)(?:\s*!=\s*(?:0|NULL))?\s*\)\s+('"$free"'\s*\((?:\s*\([^)]+\))?\s*\1\s*\))/$2/s'
+
+# Use the following to remove redundant uses of kfree inside braces.
+# Note that -0777 puts perl in slurp-whole-file mode;
+# but we have plenty of memory, these days...
+free=kfree
+git grep -l -z "$free *(" \
+ | xargs -0 useless-if-before-free -l --name="$free" \
+ | xargs -0 perl -0777 -pi -e \
+ 's/\bif\s*\(\s*(\S+?)(?:\s*!=\s*(?:0|NULL))?\s*\)\s*\{\s*('"$free"'\s*\((?:\s*\([^)]+\))?\s*\1\s*\);)\s*\}[^\n]*$/$2/gms'