[PATCH] checkpatch: warn on Rust unwrap and expect calls

Rust panic paths are discouraged in kernel code because panics currently
lead to BUG-like behavior. Add a checkpatch warning for newly added Rust
uses of unwrap(), unwrap_err(), expect() and expect_err() so contributors
notice them during patch review.

Suggested-by: Miguel Ojeda <[email protected]>
Link: https://github.com/Rust-for-Linux/linux/issues/1191
Signed-off-by: Harish-CS <[email protected]>
---
 Documentation/dev-tools/checkpatch.rst | 4 ++++
 scripts/checkpatch.pl                  | 9 +++++++++
 2 files changed, 13 insertions(+)

diff --git a/Documentation/dev-tools/checkpatch.rst b/Documentation/dev-tools/checkpatch.rst
index 6139a08c34cd..afa9787c1b9f 100644
--- a/Documentation/dev-tools/checkpatch.rst
+++ b/Documentation/dev-tools/checkpatch.rst
@@ -303,6 +303,10 @@ API usage
 
     See: https://www.kernel.org/doc/html/latest/process/deprecated.html#bug-and-bug-on
 
+  **RUST_PANIC_METHODS**
+    Rust methods that panic, such as unwrap() and expect(), should be
+    avoided.  Handle the error explicitly instead.
+
   **CONSIDER_KSTRTO**
     The simple_strtol(), simple_strtoll(), simple_strtoul(), and
     simple_strtoull() functions explicitly ignore overflows, which
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 2b7a42bbdd94..5bdb065370ea 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3972,6 +3972,15 @@ sub process {
 			}
 		}
 
+# avoid Rust panicking methods
+		if ($realfile =~ /\.rs$/ &&
+		    $line =~ /^\+.*\.(?:unwrap(?:_err)?|expect(?:_err)?)\s*\(/) {
+			my $msg_level = \&WARN;
+			$msg_level = \&CHK if ($file);
+			&{$msg_level}("RUST_PANIC_METHODS",
+				      "Avoid Rust panicking methods such as unwrap() and expect(); handle the error instead\n" . $herecurr);
+		}
+
 # check for .L prefix local symbols in .S files
 		if ($realfile =~ /\.S$/ &&
 		    $line =~ /^\+\s*(?:[A-Z]+_)?SYM_[A-Z]+_(?:START|END)(?:_[A-Z_]+)?\s*\(\s*\.L/) {
-- 
2.50.1 (Apple Git-155)