linux-kernel - [PATCH] compiler.h: unify __UNIQUE

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Message-ID: <20230831-unique_id-v1-1-28bacd18eb1d@google.com>
Date:   Thu, 31 Aug 2023 09:33:40 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Nathan Chancellor <nathan@...nel.org>, Tom Rix <trix@...hat.com>,
        Luc Van Oostenryck <luc.vanoostenryck@...il.com>,
        llvm@...ts.linux.dev, linux-kernel@...r.kernel.org,
        linux-sparse@...r.kernel.org,
        Rusty Russell <rusty@...tcorp.com.au>,
        Jan Beulich <jbeulich@...e.com>, Arnd Bergmann <arnd@...db.de>,
        Michal Marek <mmarek@...e.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: [PATCH] compiler.h: unify __UNIQUE_ID

commit 6f33d58794ef ("__UNIQUE_ID()")
added a fallback definition of __UNIQUE_ID because gcc 4.2 and older did
not support __COUNTER__.

Also, this commit is effectively a revert of
commit b41c29b0527c ("Kbuild: provide a __UNIQUE_ID for clang")
which mentions clang 2.6+ supporting __COUNTER__.

Documentation/process/changes.rst currently lists the minimum supported
version of these compilers as:
- gcc: 5.1
- clang: 11.0.0
It should be safe to say that __COUNTER__ is well supported by this
point.

Signed-off-by: Nick Desaulniers <ndesaulniers@...gle.com>
---
 include/linux/compiler-clang.h | 5 -----
 include/linux/compiler-gcc.h   | 2 --
 include/linux/compiler.h       | 5 +----
 3 files changed, 1 insertion(+), 11 deletions(-)

diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
index 9b673fefcef8..ddab1ef22bee 100644
--- a/include/linux/compiler-clang.h
+++ b/include/linux/compiler-clang.h
@@ -14,11 +14,6 @@
 #undef __cleanup
 #define __cleanup(func) __maybe_unused __attribute__((__cleanup__(func)))
 
-/* same as gcc, this was present in clang-2.6 so we can assume it works
- * with any version that can compile the kernel
- */
-#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
-
 /* all clang versions usable with the kernel support KASAN ABI version 5 */
 #define KASAN_ABI_VERSION 5
 
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 7af9e34ec261..2ceba3fe4ec1 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -39,8 +39,6 @@
 #define __noretpoline __attribute__((__indirect_branch__("keep")))
 #endif
 
-#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
-
 #if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
 #define __latent_entropy __attribute__((latent_entropy))
 #endif
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index d7779a18b24f..174099fdc485 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -177,10 +177,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 	__asm__ ("" : "=r" (var) : "0" (var))
 #endif
 
-/* Not-quite-unique ID. */
-#ifndef __UNIQUE_ID
-# define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
-#endif
+#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
 
 /**
  * data_race - mark an expression as containing intentional data races

---
base-commit: b97d64c722598ffed42ece814a2cb791336c6679
change-id: 20230831-unique_id-483938cc20aa

Best regards,
-- 
Nick Desaulniers <ndesaulniers@...gle.com>