linux-kernel - [PATCH 3/3] rust: macros: Allow specifying multiple module aliases

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Message-Id: <20230224-rust-macros-v1-3-b39fae46e102@asahilina.net>
Date:   Fri, 24 Feb 2023 16:25:57 +0900
From:   Asahi Lina <lina@...hilina.net>
To:     Miguel Ojeda <ojeda@...nel.org>,
        Alex Gaynor <alex.gaynor@...il.com>,
        Wedson Almeida Filho <wedsonaf@...il.com>,
        Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>,
        Björn Roy Baron <bjorn3_gh@...tonmail.com>
Cc:     rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org,
        asahi@...ts.linux.dev, Asahi Lina <lina@...hilina.net>,
        Finn Behrens <me@...enk.dev>,
        Sumera Priyadarsini <sylphrenadin@...il.com>
Subject: [PATCH 3/3] rust: macros: Allow specifying multiple module aliases

Modules can (and usually do) have multiple alias tags, in order to
specify multiple possible device matches for autoloading. Allow this by
changing the alias ModuleInfo field to an Option<Vec<String>>.

Note: For normal device IDs this is autogenerated by modpost (which is
not properly integrated with Rust support yet), so it is useful to be
able to manually add device match aliases for now, and should still be
useful in the future for corner cases that modpost does not handle.

This pulls in the expect_group() helper from the rfl/rust branch
(with credit to authors).

Co-developed-by: Miguel Ojeda <ojeda@...nel.org>
Signed-off-by: Miguel Ojeda <ojeda@...nel.org>
Co-developed-by: Finn Behrens <me@...enk.dev>
Signed-off-by: Finn Behrens <me@...enk.dev>
Co-developed-by: Sumera Priyadarsini <sylphrenadin@...il.com>
Signed-off-by: Sumera Priyadarsini <sylphrenadin@...il.com>
Signed-off-by: Asahi Lina <lina@...hilina.net>
---
 rust/macros/helpers.rs | 10 +++++++++-
 rust/macros/module.rs  | 30 +++++++++++++++++++++++++-----
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/rust/macros/helpers.rs b/rust/macros/helpers.rs
index 65706ecc007e..15bf0c892421 100644
--- a/rust/macros/helpers.rs
+++ b/rust/macros/helpers.rs
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 
-use proc_macro::{token_stream, Punct, TokenTree};
+use proc_macro::{token_stream, Group, Punct, TokenTree};
 
 pub(crate) fn try_ident(it: &mut token_stream::IntoIter) -> Option<String> {
     if let Some(TokenTree::Ident(ident)) = it.next() {
@@ -56,6 +56,14 @@ pub(crate) fn expect_string_ascii(it: &mut token_stream::IntoIter) -> String {
     string
 }
 
+pub(crate) fn expect_group(it: &mut token_stream::IntoIter) -> Group {
+    if let TokenTree::Group(group) = it.next().expect("Reached end of token stream for Group") {
+        group
+    } else {
+        panic!("Expected Group");
+    }
+}
+
 pub(crate) fn expect_end(it: &mut token_stream::IntoIter) {
     if it.next().is_some() {
         panic!("Expected end");
diff --git a/rust/macros/module.rs b/rust/macros/module.rs
index 07503b242d2d..92cb35c235e1 100644
--- a/rust/macros/module.rs
+++ b/rust/macros/module.rs
@@ -1,9 +1,27 @@
 // SPDX-License-Identifier: GPL-2.0
 
 use crate::helpers::*;
-use proc_macro::{token_stream, Literal, TokenStream, TokenTree};
+use proc_macro::{token_stream, Delimiter, Literal, TokenStream, TokenTree};
 use std::fmt::Write;
 
+fn expect_string_array(it: &mut token_stream::IntoIter) -> Vec<String> {
+    let group = expect_group(it);
+    assert_eq!(group.delimiter(), Delimiter::Bracket);
+    let mut values = Vec::new();
+    let mut it = group.stream().into_iter();
+
+    while let Some(val) = try_string(&mut it) {
+        assert!(val.is_ascii(), "Expected ASCII string");
+        values.push(val);
+        match it.next() {
+            Some(TokenTree::Punct(punct)) => assert_eq!(punct.as_char(), ','),
+            None => break,
+            _ => panic!("Expected ',' or end of array"),
+        }
+    }
+    values
+}
+
 struct ModInfoBuilder<'a> {
     module: &'a str,
     counter: usize,
@@ -78,7 +96,7 @@ struct ModuleInfo {
     name: String,
     author: Option<String>,
     description: Option<String>,
-    alias: Option<String>,
+    alias: Option<Vec<String>>,
 }
 
 impl ModuleInfo {
@@ -112,7 +130,7 @@ impl ModuleInfo {
                 "author" => info.author = Some(expect_string(it)),
                 "description" => info.description = Some(expect_string(it)),
                 "license" => info.license = expect_string_ascii(it),
-                "alias" => info.alias = Some(expect_string_ascii(it)),
+                "alias" => info.alias = Some(expect_string_array(it)),
                 _ => panic!(
                     "Unknown key \"{}\". Valid keys are: {:?}.",
                     key, EXPECTED_KEYS
@@ -163,8 +181,10 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream {
         modinfo.emit("description", &description);
     }
     modinfo.emit("license", &info.license);
-    if let Some(alias) = info.alias {
-        modinfo.emit("alias", &alias);
+    if let Some(aliases) = info.alias {
+        for alias in aliases {
+            modinfo.emit("alias", &alias);
+        }
     }
 
     // Built-in modules also export the `file` modinfo string.

-- 
2.35.1