From: Jim Cromie <jim.cromie@gmail.com>
To: jbaron@akamai.com, daniel.vetter@ffwll.ch,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
amd-gfx@lists.freedesktop.org,
intel-gvt-dev@lists.freedesktop.org,
intel-gfx@lists.freedesktop.org
Cc: jani.nikula@intel.com, ville.syrjala@linux.intel.com,
seanpaul@chromium.org, robdclark@gmail.com,
gregkh@linuxfoundation.org, Jim Cromie <jim.cromie@gmail.com>,
Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Tom Rix <trix@redhat.com>,
linux-sparse@vger.kernel.org, llvm@lists.linux.dev
Subject: [PATCH v4 18/21] compiler.h: RFC - s/__LINE__/__COUNTER__/ in __UNIQUE_ID fallback
Date: Thu, 13 Jul 2023 10:36:23 -0600 [thread overview]
Message-ID: <20230713163626.31338-19-jim.cromie@gmail.com> (raw)
In-Reply-To: <20230713163626.31338-1-jim.cromie@gmail.com>
We currently have 3 defns for __UNIQUE_ID(); gcc and clang are using
__COUNTER__ for real uniqueness, 3rd just uses __LINE__, which should
fail on this (and harder to avoid situations):
DECLARE_FOO(); DECLARE_FOO();
Its 2023, can we haz a no-fallback __UNIQUE_ID ?
NOTE:
This also changes __UNIQUE_ID_ to _kaUID_. Ive been getting
lkp-reports of collisions on names which should be unique; this
shouldnt happen on gcc & clang, but does on some older ones, on some
platforms, on some allyes & rand-configs. Like this:
mips64-linux-ld:
drivers/gpu/drm/display/drm_dp_helper.o:(__dyndbg_class_users+0x0):
multiple definition of `__UNIQUE_ID_ddebug_class_user405';
drivers/gpu/drm/drm_gem_shmem_helper.o:(__dyndbg_class_users+0x0):
first defined here
Like above, the collision reports appear to always be 3-digit
counters, which look like line-numbers. Changing to _kaUID_ in this
defn should make it more obvious (in *.i file) when a fallback has
happened. To be clear, I havent seen it yet. Nor have I seen the
multiple-defn problem above since adding this patch.
Lets see what lkp-robot says about this.
CC: Luc Van Oostenryck <luc.vanoostenryck@gmail.com> (maintainer:SPARSE CHECKER)
CC: Nathan Chancellor <nathan@kernel.org> (supporter:CLANG/LLVM BUILD SUPPORT)
CC: Nick Desaulniers <ndesaulniers@google.com> (supporter:CLANG/LLVM BUILD SUPPORT)
CC: Tom Rix <trix@redhat.com> (reviewer:CLANG/LLVM BUILD SUPPORT)
CC: linux-sparse@vger.kernel.org (open list:SPARSE CHECKER)
CC: linux-kernel@vger.kernel.org (open list)
CC: llvm@lists.linux.dev (open list:CLANG/LLVM BUILD SUPPORT)
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
include/linux/compiler.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index d7779a18b24f..677d6c47cd9e 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -177,9 +177,9 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
__asm__ ("" : "=r" (var) : "0" (var))
#endif
-/* Not-quite-unique ID. */
+/* JFTI: to fix Not-quite-unique ID */
#ifndef __UNIQUE_ID
-# define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)
+# define __UNIQUE_ID(prefix) __PASTE(__PASTE(_kaUID_, prefix), __COUNTER__)
#endif
/**
--
2.41.0
next parent reply other threads:[~2023-07-13 16:38 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20230713163626.31338-1-jim.cromie@gmail.com>
2023-07-13 16:36 ` Jim Cromie [this message]
2023-07-13 17:19 ` [PATCH v4 18/21] compiler.h: RFC - s/__LINE__/__COUNTER__/ in __UNIQUE_ID fallback Nathan Chancellor
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