From: Will Deacon <will@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: elver@google.com, tglx@linutronix.de, paulmck@kernel.org,
mingo@kernel.org, peterz@infradead.org, will@kernel.org
Subject: [PATCH v5 13/18] locking/barriers: Use '__unqual_scalar_typeof' for load-acquire macros
Date: Mon, 11 May 2020 21:41:45 +0100 [thread overview]
Message-ID: <20200511204150.27858-14-will@kernel.org> (raw)
In-Reply-To: <20200511204150.27858-1-will@kernel.org>
Passing volatile-qualified pointers to the asm-generic implementations of
the load-acquire macros results in a re-load from the stack due to the
temporary result variable inheriting the volatile semantics thanks to the
use of 'typeof()'.
Define these temporary variables using 'unqual_scalar_typeof' to drop
the volatile qualifier in the case that they are scalar types.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Will Deacon <will@kernel.org>
---
include/asm-generic/barrier.h | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/include/asm-generic/barrier.h b/include/asm-generic/barrier.h
index 85b28eb80b11..2eacaf7d62f6 100644
--- a/include/asm-generic/barrier.h
+++ b/include/asm-generic/barrier.h
@@ -128,10 +128,10 @@ do { \
#ifndef __smp_load_acquire
#define __smp_load_acquire(p) \
({ \
- typeof(*p) ___p1 = READ_ONCE(*p); \
+ __unqual_scalar_typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
__smp_mb(); \
- ___p1; \
+ (typeof(*p))___p1; \
})
#endif
@@ -183,10 +183,10 @@ do { \
#ifndef smp_load_acquire
#define smp_load_acquire(p) \
({ \
- typeof(*p) ___p1 = READ_ONCE(*p); \
+ __unqual_scalar_typeof(*p) ___p1 = READ_ONCE(*p); \
compiletime_assert_atomic_type(*p); \
barrier(); \
- ___p1; \
+ (typeof(*p))___p1; \
})
#endif
@@ -229,14 +229,14 @@ do { \
#ifndef smp_cond_load_relaxed
#define smp_cond_load_relaxed(ptr, cond_expr) ({ \
typeof(ptr) __PTR = (ptr); \
- typeof(*ptr) VAL; \
+ __unqual_scalar_typeof(*ptr) VAL; \
for (;;) { \
VAL = READ_ONCE(*__PTR); \
if (cond_expr) \
break; \
cpu_relax(); \
} \
- VAL; \
+ (typeof(*ptr))VAL; \
})
#endif
@@ -250,10 +250,10 @@ do { \
*/
#ifndef smp_cond_load_acquire
#define smp_cond_load_acquire(ptr, cond_expr) ({ \
- typeof(*ptr) _val; \
+ __unqual_scalar_typeof(*ptr) _val; \
_val = smp_cond_load_relaxed(ptr, cond_expr); \
smp_acquire__after_ctrl_dep(); \
- _val; \
+ (typeof(*ptr))_val; \
})
#endif
--
2.26.2.645.ge9eca65c58-goog
next prev parent reply other threads:[~2020-05-11 20:43 UTC|newest]
Thread overview: 127+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-11 20:41 [PATCH v5 00/18] Rework READ_ONCE() to improve codegen Will Deacon
2020-05-11 20:41 ` [PATCH v5 01/18] sparc32: mm: Fix argument checking in __srmmu_get_nocache() Will Deacon
2020-05-12 14:37 ` [tip: locking/kcsan] " tip-bot2 for Will Deacon
2020-05-11 20:41 ` [PATCH v5 02/18] sparc32: mm: Restructure sparc32 MMU page-table layout Will Deacon
2020-05-12 14:37 ` [tip: locking/kcsan] " tip-bot2 for Will Deacon
2020-05-11 20:41 ` [PATCH v5 03/18] sparc32: mm: Change pgtable_t type to pte_t * instead of struct page * Will Deacon
2020-05-12 14:36 ` [tip: locking/kcsan] " tip-bot2 for Will Deacon
2020-05-11 20:41 ` [PATCH v5 04/18] sparc32: mm: Reduce allocation size for PMD and PTE tables Will Deacon
2020-05-12 14:36 ` [tip: locking/kcsan] " tip-bot2 for Will Deacon
2020-05-17 0:00 ` [PATCH v5 04/18] " Guenter Roeck
2020-05-17 0:07 ` Guenter Roeck
2020-05-18 8:37 ` Will Deacon
2020-05-18 9:18 ` Mike Rapoport
2020-05-18 9:48 ` Guenter Roeck
2020-05-18 14:23 ` Mike Rapoport
2020-05-18 16:08 ` Guenter Roeck
2020-05-18 18:11 ` Ira Weiny
2020-05-18 18:14 ` Ira Weiny
2020-05-18 18:09 ` Guenter Roeck
2020-05-18 18:21 ` Ira Weiny
2020-05-18 19:15 ` Mike Rapoport
2020-05-19 16:40 ` Guenter Roeck
2020-05-20 17:03 ` Mike Rapoport
2020-05-20 19:03 ` Guenter Roeck
2020-05-20 19:51 ` Mike Rapoport
2020-05-21 23:02 ` Guenter Roeck
2020-05-24 12:32 ` Mike Rapoport
2020-05-24 14:01 ` Guenter Roeck
2020-05-26 13:26 ` Will Deacon
2020-05-26 14:01 ` Will Deacon
2020-05-26 15:21 ` Mike Rapoport
2020-05-26 16:18 ` Guenter Roeck
2020-05-26 16:29 ` Mike Rapoport
2020-05-26 17:15 ` Guenter Roeck
2020-05-11 20:41 ` [PATCH v5 05/18] compiler/gcc: Raise minimum GCC version for kernel builds to 4.8 Will Deacon
2020-05-12 14:36 ` [tip: locking/kcsan] " tip-bot2 for Will Deacon
2020-05-11 20:41 ` [PATCH v5 06/18] netfilter: Avoid assigning 'const' pointer to non-const pointer Will Deacon
2020-05-12 14:36 ` [tip: locking/kcsan] " tip-bot2 for Will Deacon
2020-05-11 20:41 ` [PATCH v5 07/18] net: tls: " Will Deacon
2020-05-12 14:36 ` [tip: locking/kcsan] " tip-bot2 for Will Deacon
2020-05-11 20:41 ` [PATCH v5 08/18] fault_inject: Don't rely on "return value" from WRITE_ONCE() Will Deacon
2020-05-12 14:36 ` [tip: locking/kcsan] " tip-bot2 for Will Deacon
2020-05-11 20:41 ` [PATCH v5 09/18] arm64: csum: Disable KASAN for do_csum() Will Deacon
2020-05-12 14:36 ` [tip: locking/kcsan] " tip-bot2 for Will Deacon
2020-05-11 20:41 ` [PATCH v5 10/18] READ_ONCE: Simplify implementations of {READ,WRITE}_ONCE() Will Deacon
2020-05-12 14:36 ` [tip: locking/kcsan] " tip-bot2 for Will Deacon
2020-05-11 20:41 ` [PATCH v5 11/18] READ_ONCE: Enforce atomicity for {READ,WRITE}_ONCE() memory accesses Will Deacon
2020-05-12 14:36 ` [tip: locking/kcsan] " tip-bot2 for Will Deacon
2020-05-11 20:41 ` [PATCH v5 12/18] READ_ONCE: Drop pointer qualifiers when reading from scalar types Will Deacon
2020-05-12 14:36 ` [tip: locking/kcsan] " tip-bot2 for Will Deacon
2020-05-11 20:41 ` Will Deacon [this message]
2020-05-12 14:36 ` [tip: locking/kcsan] locking/barriers: Use '__unqual_scalar_typeof' for load-acquire macros tip-bot2 for Will Deacon
2020-05-11 20:41 ` [PATCH v5 14/18] arm64: barrier: Use '__unqual_scalar_typeof' for acquire/release macros Will Deacon
2020-05-12 14:36 ` [tip: locking/kcsan] " tip-bot2 for Will Deacon
2020-05-11 20:41 ` [PATCH v5 15/18] gcov: Remove old GCC 3.4 support Will Deacon
2020-05-12 14:36 ` [tip: locking/kcsan] " tip-bot2 for Will Deacon
2020-05-11 20:41 ` [PATCH v5 16/18] kcsan: Rework data_race() so that it can be used by READ_ONCE() Will Deacon
2020-05-12 14:36 ` [tip: locking/kcsan] " tip-bot2 for Will Deacon
2020-05-11 20:41 ` [PATCH v5 17/18] READ_ONCE: Use data_race() to avoid KCSAN instrumentation Will Deacon
2020-05-12 8:23 ` Peter Zijlstra
2020-05-12 9:49 ` Will Deacon
2020-05-12 14:36 ` [tip: locking/kcsan] " tip-bot2 for Will Deacon
2020-05-20 22:17 ` Borislav Petkov
2020-05-20 22:30 ` Marco Elver
2020-05-21 7:25 ` Borislav Petkov
2020-05-21 9:37 ` Marco Elver
2020-05-21 3:30 ` Nathan Chancellor
2020-05-22 16:08 ` [tip: locking/kcsan] compiler.h: Avoid nested statement expression in data_race() tip-bot2 for Marco Elver
2020-05-11 20:41 ` [PATCH v5 18/18] linux/compiler.h: Remove redundant '#else' Will Deacon
2020-05-12 14:36 ` [tip: locking/kcsan] " tip-bot2 for Will Deacon
2020-05-12 8:18 ` [PATCH v5 00/18] Rework READ_ONCE() to improve codegen Peter Zijlstra
2020-05-12 17:53 ` Marco Elver
2020-05-12 18:55 ` Marco Elver
2020-05-12 19:07 ` Peter Zijlstra
2020-05-12 20:31 ` Marco Elver
2020-05-13 11:10 ` Peter Zijlstra
2020-05-13 11:14 ` Peter Zijlstra
2020-05-13 11:48 ` Marco Elver
2020-05-13 12:32 ` Peter Zijlstra
2020-05-13 12:40 ` Will Deacon
2020-05-13 13:15 ` Marco Elver
2020-05-13 13:24 ` Peter Zijlstra
2020-05-13 13:58 ` Marco Elver
2020-05-14 11:21 ` Peter Zijlstra
2020-05-14 11:24 ` Peter Zijlstra
2020-05-14 11:35 ` Peter Zijlstra
2020-05-14 12:01 ` Will Deacon
2020-05-14 12:27 ` Peter Zijlstra
2020-05-14 13:07 ` Marco Elver
2020-05-14 13:14 ` Peter Zijlstra
2020-05-14 12:20 ` Peter Zijlstra
2020-05-14 14:13 ` Peter Zijlstra
2020-05-14 14:20 ` Marco Elver
2020-05-15 9:20 ` Peter Zijlstra
2020-05-13 16:50 ` Will Deacon
2020-05-13 17:32 ` Marco Elver
2020-05-13 17:47 ` Will Deacon
2020-05-13 18:54 ` Marco Elver
2020-05-13 21:25 ` Will Deacon
2020-05-14 7:31 ` Marco Elver
2020-05-14 11:05 ` Will Deacon
2020-05-14 13:35 ` Marco Elver
2020-05-14 13:47 ` Peter Zijlstra
2020-05-14 13:50 ` Peter Zijlstra
2020-05-14 13:56 ` Peter Zijlstra
2020-05-14 14:24 ` Peter Zijlstra
2020-05-14 15:09 ` Thomas Gleixner
2020-05-14 15:29 ` Marco Elver
2020-05-14 19:37 ` Thomas Gleixner
2020-05-15 13:55 ` David Laight
2020-05-15 14:04 ` Marco Elver
2020-05-15 14:07 ` Peter Zijlstra
2020-05-14 15:38 ` Paul E. McKenney
2020-05-22 16:08 ` [tip: locking/kcsan] kcsan: Restrict supported compilers tip-bot2 for Marco Elver
2020-06-03 18:52 ` [PATCH v5 00/18] Rework READ_ONCE() to improve codegen Borislav Petkov
2020-06-03 19:23 ` Marco Elver
2020-06-03 22:05 ` Borislav Petkov
2020-06-08 17:32 ` Martin Liška
2020-06-08 19:56 ` Marco Elver
2020-06-09 11:55 ` Martin Liška
2020-06-09 12:36 ` Martin Liška
2020-06-09 13:45 ` Marco Elver
2020-05-22 16:08 ` [tip: locking/kcsan] kcsan: Remove 'noinline' from __no_kcsan_or_inline tip-bot2 for Marco Elver
2020-05-13 13:21 ` [PATCH v5 00/18] Rework READ_ONCE() to improve codegen David Laight
2020-05-13 16:32 ` Thomas Gleixner
2020-05-12 21:14 ` Will Deacon
2020-05-12 22:00 ` Marco Elver
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