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Message-Id: <20230504200527.1935944-2-mathieu.desnoyers@efficios.com>
Date: Thu, 4 May 2023 16:05:15 -0400
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
"Paul E. McKenney" <paulmck@...nel.org>,
Joel Fernandes <joel@...lfernandes.org>,
Josh Triplett <josh@...htriplett.org>,
Boqun Feng <boqun.feng@...il.com>,
Steven Rostedt <rostedt@...dmis.org>,
Lai Jiangshan <jiangshanlai@...il.com>,
Zqiang <qiang1.zhang@...el.com>
Subject: [RFC PATCH 01/13] rcu: rcupdate.h: Fix parentheses around macro parameter use
linux/rcupdate.h macros use the *p parameter without parentheses, e.g.:
typeof(*p)
rather than
typeof(*(p))
The following test-case shows how it can generate confusion due to C
operator precedence being reversed compared to the expectations:
#define m(p) \
do { \
__typeof__(*p) v = 0; \
} while (0)
void fct(unsigned long long *p1)
{
m(p1 + 1); /* works */
m(1 + p1); /* broken */
}
Add missing parentheses around macro parameter use in the following
pattern to ensure operator precedence behaves as expected:
- m(&p) is changed for m(&(p)).
Remove useless parentheses in the following macro argument usage
patterns:
- m((x), y) is changed for m(x, y), because comma has the lowest
operator precedence, and thus the extra parentheses are useless.
- "(_r_a_p__v) where _r_a_p__v is a variable and not a macro parameter,
is changed for "_r_a_p__v",
An extra whitespace is also removed in kvfree_rcu_arg_2() for
consistency.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: "Paul E. McKenney" <paulmck@...nel.org>
Cc: Joel Fernandes <joel@...lfernandes.org>
Cc: Josh Triplett <josh@...htriplett.org>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Lai Jiangshan <jiangshanlai@...il.com>
Cc: Zqiang <qiang1.zhang@...el.com>
---
include/linux/rcupdate.h | 46 ++++++++++++++++++++--------------------
1 file changed, 23 insertions(+), 23 deletions(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index dcd2cf1e8326..4f26c3080953 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -215,7 +215,7 @@ void rcu_tasks_trace_qs_blkd(struct task_struct *t);
\
if (likely(!READ_ONCE((t)->trc_reader_special.b.need_qs)) && \
likely(!___rttq_nesting)) { \
- rcu_trc_cmpxchg_need_qs((t), 0, TRC_NEED_QS_CHECKED); \
+ rcu_trc_cmpxchg_need_qs(t, 0, TRC_NEED_QS_CHECKED); \
} else if (___rttq_nesting && ___rttq_nesting != INT_MIN && \
!READ_ONCE((t)->trc_reader_special.b.blocked)) { \
rcu_tasks_trace_qs_blkd(t); \
@@ -227,7 +227,7 @@ void rcu_tasks_trace_qs_blkd(struct task_struct *t);
#define rcu_tasks_qs(t, preempt) \
do { \
- rcu_tasks_classic_qs((t), (preempt)); \
+ rcu_tasks_classic_qs(t, preempt); \
rcu_tasks_trace_qs(t); \
} while (0)
@@ -430,16 +430,16 @@ static inline void rcu_preempt_sleep_check(void) { }
#ifdef __CHECKER__
#define rcu_check_sparse(p, space) \
- ((void)(((typeof(*p) space *)p) == p))
+ ((void)(((typeof(*(p)) space *)(p)) == (p)))
#else /* #ifdef __CHECKER__ */
#define rcu_check_sparse(p, space)
#endif /* #else #ifdef __CHECKER__ */
#define __unrcu_pointer(p, local) \
({ \
- typeof(*p) *local = (typeof(*p) *__force)(p); \
+ typeof(*(p)) *local = (typeof(*(p)) *__force)(p); \
rcu_check_sparse(p, __rcu); \
- ((typeof(*p) __force __kernel *)(local)); \
+ ((typeof(*(p)) __force __kernel *)(local)); \
})
/**
* unrcu_pointer - mark a pointer as not being RCU protected
@@ -452,29 +452,29 @@ static inline void rcu_preempt_sleep_check(void) { }
#define __rcu_access_pointer(p, local, space) \
({ \
- typeof(*p) *local = (typeof(*p) *__force)READ_ONCE(p); \
+ typeof(*(p)) *local = (typeof(*(p)) *__force)READ_ONCE(p); \
rcu_check_sparse(p, space); \
- ((typeof(*p) __force __kernel *)(local)); \
+ ((typeof(*(p)) __force __kernel *)(local)); \
})
#define __rcu_dereference_check(p, local, c, space) \
({ \
/* Dependency order vs. p above. */ \
- typeof(*p) *local = (typeof(*p) *__force)READ_ONCE(p); \
+ typeof(*(p)) *local = (typeof(*(p)) *__force)READ_ONCE(p); \
RCU_LOCKDEP_WARN(!(c), "suspicious rcu_dereference_check() usage"); \
rcu_check_sparse(p, space); \
- ((typeof(*p) __force __kernel *)(local)); \
+ ((typeof(*(p)) __force __kernel *)(local)); \
})
#define __rcu_dereference_protected(p, local, c, space) \
({ \
RCU_LOCKDEP_WARN(!(c), "suspicious rcu_dereference_protected() usage"); \
rcu_check_sparse(p, space); \
- ((typeof(*p) __force __kernel *)(p)); \
+ ((typeof(*(p)) __force __kernel *)(p)); \
})
#define __rcu_dereference_raw(p, local) \
({ \
/* Dependency order vs. p above. */ \
typeof(p) local = READ_ONCE(p); \
- ((typeof(*p) __force __kernel *)(local)); \
+ ((typeof(*(p)) __force __kernel *)(local)); \
})
#define rcu_dereference_raw(p) __rcu_dereference_raw(p, __UNIQUE_ID(rcu))
@@ -520,10 +520,10 @@ do { \
uintptr_t _r_a_p__v = (uintptr_t)(v); \
rcu_check_sparse(p, __rcu); \
\
- if (__builtin_constant_p(v) && (_r_a_p__v) == (uintptr_t)NULL) \
- WRITE_ONCE((p), (typeof(p))(_r_a_p__v)); \
+ if (__builtin_constant_p(v) && _r_a_p__v == (uintptr_t)NULL) \
+ WRITE_ONCE(p, (typeof(p))_r_a_p__v); \
else \
- smp_store_release(&p, RCU_INITIALIZER((typeof(p))_r_a_p__v)); \
+ smp_store_release(&(p), RCU_INITIALIZER((typeof(p))_r_a_p__v));\
} while (0)
/**
@@ -539,8 +539,8 @@ do { \
*/
#define rcu_replace_pointer(rcu_ptr, ptr, c) \
({ \
- typeof(ptr) __tmp = rcu_dereference_protected((rcu_ptr), (c)); \
- rcu_assign_pointer((rcu_ptr), (ptr)); \
+ typeof(ptr) __tmp = rcu_dereference_protected(rcu_ptr, c); \
+ rcu_assign_pointer(rcu_ptr, ptr); \
__tmp; \
})
@@ -571,7 +571,7 @@ do { \
* down multi-linked structures after a grace period has elapsed. However,
* rcu_dereference_protected() is normally preferred for this use case.
*/
-#define rcu_access_pointer(p) __rcu_access_pointer((p), __UNIQUE_ID(rcu), __rcu)
+#define rcu_access_pointer(p) __rcu_access_pointer(p, __UNIQUE_ID(rcu), __rcu)
/**
* rcu_dereference_check() - rcu_dereference with debug checking
@@ -607,7 +607,7 @@ do { \
* annotated as __rcu.
*/
#define rcu_dereference_check(p, c) \
- __rcu_dereference_check((p), __UNIQUE_ID(rcu), \
+ __rcu_dereference_check(p, __UNIQUE_ID(rcu), \
(c) || rcu_read_lock_held(), __rcu)
/**
@@ -623,7 +623,7 @@ do { \
* rcu_read_lock() but also rcu_read_lock_bh() into account.
*/
#define rcu_dereference_bh_check(p, c) \
- __rcu_dereference_check((p), __UNIQUE_ID(rcu), \
+ __rcu_dereference_check(p, __UNIQUE_ID(rcu), \
(c) || rcu_read_lock_bh_held(), __rcu)
/**
@@ -639,7 +639,7 @@ do { \
* only rcu_read_lock() but also rcu_read_lock_sched() into account.
*/
#define rcu_dereference_sched_check(p, c) \
- __rcu_dereference_check((p), __UNIQUE_ID(rcu), \
+ __rcu_dereference_check(p, __UNIQUE_ID(rcu), \
(c) || rcu_read_lock_sched_held(), \
__rcu)
@@ -651,7 +651,7 @@ do { \
* rcu_read_lock_held().
*/
#define rcu_dereference_raw_check(p) \
- __rcu_dereference_check((p), __UNIQUE_ID(rcu), 1, __rcu)
+ __rcu_dereference_check(p, __UNIQUE_ID(rcu), 1, __rcu)
/**
* rcu_dereference_protected() - fetch RCU pointer when updates prevented
@@ -670,7 +670,7 @@ do { \
* but very ugly failures.
*/
#define rcu_dereference_protected(p, c) \
- __rcu_dereference_protected((p), __UNIQUE_ID(rcu), (c), __rcu)
+ __rcu_dereference_protected(p, __UNIQUE_ID(rcu), c, __rcu)
/**
@@ -1021,7 +1021,7 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
#define KVFREE_GET_MACRO(_1, _2, NAME, ...) NAME
#define kvfree_rcu_arg_2(ptr, rhf) \
do { \
- typeof (ptr) ___p = (ptr); \
+ typeof(ptr) ___p = (ptr); \
\
if (___p) { \
BUILD_BUG_ON(!__is_kvfree_rcu_offset(offsetof(typeof(*(ptr)), rhf))); \
--
2.25.1
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