From: Chun-Hung Tseng <henrybear327@gmail.com>
To: luc.vanoostenryck@gmail.com, linux-sparse@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: Chun-Hung Tseng <henrybear327@gmail.com>,
Jim Huang <jserv@ccns.ncku.edu.tw>
Subject: [PATCH] compiler.h: Improve __branch_check__ by using __UNIQUE_ID()
Date: Mon, 17 Jun 2024 14:29:35 +0200 [thread overview]
Message-ID: <20240617122934.2650453-1-henrybear327@gmail.com> (raw)
This commit replaced two hard-to-distinguish variables ______r and
______f to improve code readability and reduce variable name shadowing
issue.
______r is renamed by leveraging __UNIQUE_ID(branch_check) in
___branch_check__, and callers of the affected macros are adjusted.
__UNIQUE_ID(branch_check) will generate unique variable names during
compilation, which eliminates the need for ______r. This avoids the
variable name shadowing issue, or at least makes those wishing to cause
shadowing problems work much harder to do so.
______f in ftrace_likely_data struct is renamed using
__UNIQUE_ID(branch_check_data), following the same rationale above.
The same idea is used for the commit 589a9785ee3a ("min/max: remove sparse
warnings when they're nested"), and commit 24ba53017e18 ("rcu: Replace
________p1 and _________p1 with __UNIQUE_ID(rcu)").
Signed-off-by: Chun-Hung Tseng <henrybear327@gmail.com>
Signed-off-by: Jim Huang <jserv@ccns.ncku.edu.tw>
---
include/linux/compiler.h | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 8c252e073bd8..b95e0990d52f 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -19,20 +19,20 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
#define likely_notrace(x) __builtin_expect(!!(x), 1)
#define unlikely_notrace(x) __builtin_expect(!!(x), 0)
-#define __branch_check__(x, expect, is_constant) ({ \
- long ______r; \
+#define __branch_check__(x, local, local_data, expect, is_constant) ({ \
+ long local; \
static struct ftrace_likely_data \
__aligned(4) \
__section("_ftrace_annotated_branch") \
- ______f = { \
+ local_data = { \
.data.func = __func__, \
.data.file = __FILE__, \
.data.line = __LINE__, \
}; \
- ______r = __builtin_expect(!!(x), expect); \
- ftrace_likely_update(&______f, ______r, \
+ local = __builtin_expect(!!(x), expect); \
+ ftrace_likely_update(&local_data, local, \
expect, is_constant); \
- ______r; \
+ local; \
})
/*
@@ -41,10 +41,14 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
* written by Daniel Walker.
*/
# ifndef likely
-# define likely(x) (__branch_check__(x, 1, __builtin_constant_p(x)))
+# define likely(x) (__branch_check__(x, __UNIQUE_ID(branch_check), \
+ __UNIQUE_ID(branch_check_data), 1, \
+ __builtin_constant_p(x)))
# endif
# ifndef unlikely
-# define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x)))
+# define unlikely(x) (__branch_check__(x, __UNIQUE_ID(branch_check), \
+ __UNIQUE_ID(branch_check_data), 0, \
+ __builtin_constant_p(x)))
# endif
#ifdef CONFIG_PROFILE_ALL_BRANCHES
--
2.34.1
next reply other threads:[~2024-06-17 12:31 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-17 12:29 Chun-Hung Tseng [this message]
-- strict thread matches above, loose matches on Subject: below --
2024-07-19 7:50 [PATCH] compiler.h: Improve __branch_check__ by using __UNIQUE_ID() Chun-Hung Tseng
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