The local_lock.h is the main entry for the local_lock_t type and
provides wrappers around internal functions prefixed with __ in
local_lock_internal.h.
Move the this_cpu_ptr() dereference of the variable from the internal to
the main header. Since it is all macro implemented, this_cpu_ptr() will
still happen within the preempt/ IRQ disabled section.
This will free the internal implementation (__) to be used on
local_lock_t types which are local variables and must not be accessed
via this_cpu_ptr().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
include/linux/local_lock.h | 20 +++++++++----------
include/linux/local_lock_internal.h | 30 ++++++++++++++---------------
2 files changed, 25 insertions(+), 25 deletions(-)
diff --git a/include/linux/local_lock.h b/include/linux/local_lock.h
index 16a2ee4f8310b..2ba8464195244 100644
--- a/include/linux/local_lock.h
+++ b/include/linux/local_lock.h
@@ -13,13 +13,13 @@
* local_lock - Acquire a per CPU local lock
* @lock: The lock variable
*/
-#define local_lock(lock) __local_lock(lock)
+#define local_lock(lock) __local_lock(this_cpu_ptr(lock))
/**
* local_lock_irq - Acquire a per CPU local lock and disable interrupts
* @lock: The lock variable
*/
-#define local_lock_irq(lock) __local_lock_irq(lock)
+#define local_lock_irq(lock) __local_lock_irq(this_cpu_ptr(lock))
/**
* local_lock_irqsave - Acquire a per CPU local lock, save and disable
@@ -28,19 +28,19 @@
* @flags: Storage for interrupt flags
*/
#define local_lock_irqsave(lock, flags) \
- __local_lock_irqsave(lock, flags)
+ __local_lock_irqsave(this_cpu_ptr(lock), flags)
/**
* local_unlock - Release a per CPU local lock
* @lock: The lock variable
*/
-#define local_unlock(lock) __local_unlock(lock)
+#define local_unlock(lock) __local_unlock(this_cpu_ptr(lock))
/**
* local_unlock_irq - Release a per CPU local lock and enable interrupts
* @lock: The lock variable
*/
-#define local_unlock_irq(lock) __local_unlock_irq(lock)
+#define local_unlock_irq(lock) __local_unlock_irq(this_cpu_ptr(lock))
/**
* local_unlock_irqrestore - Release a per CPU local lock and restore
@@ -49,7 +49,7 @@
* @flags: Interrupt flags to restore
*/
#define local_unlock_irqrestore(lock, flags) \
- __local_unlock_irqrestore(lock, flags)
+ __local_unlock_irqrestore(this_cpu_ptr(lock), flags)
/**
* local_lock_init - Runtime initialize a lock instance
@@ -64,7 +64,7 @@
* locking constrains it will _always_ fail to acquire the lock in NMI or
* HARDIRQ context on PREEMPT_RT.
*/
-#define local_trylock(lock) __local_trylock(lock)
+#define local_trylock(lock) __local_trylock(this_cpu_ptr(lock))
/**
* local_trylock_irqsave - Try to acquire a per CPU local lock, save and disable
@@ -77,7 +77,7 @@
* HARDIRQ context on PREEMPT_RT.
*/
#define local_trylock_irqsave(lock, flags) \
- __local_trylock_irqsave(lock, flags)
+ __local_trylock_irqsave(this_cpu_ptr(lock), flags)
DEFINE_GUARD(local_lock, local_lock_t __percpu*,
local_lock(_T),
@@ -91,10 +91,10 @@ DEFINE_LOCK_GUARD_1(local_lock_irqsave, local_lock_t __percpu,
unsigned long flags)
#define local_lock_nested_bh(_lock) \
- __local_lock_nested_bh(_lock)
+ __local_lock_nested_bh(this_cpu_ptr(_lock))
#define local_unlock_nested_bh(_lock) \
- __local_unlock_nested_bh(_lock)
+ __local_unlock_nested_bh(this_cpu_ptr(_lock))
DEFINE_GUARD(local_lock_nested_bh, local_lock_t __percpu*,
local_lock_nested_bh(_T),
diff --git a/include/linux/local_lock_internal.h b/include/linux/local_lock_internal.h
index 8d5ac16a9b179..b4d7b24882835 100644
--- a/include/linux/local_lock_internal.h
+++ b/include/linux/local_lock_internal.h
@@ -99,14 +99,14 @@ do { \
local_trylock_t *tl; \
local_lock_t *l; \
\
- l = (local_lock_t *)this_cpu_ptr(lock); \
+ l = (local_lock_t *)(lock); \
tl = (local_trylock_t *)l; \
_Generic((lock), \
- __percpu local_trylock_t *: ({ \
+ local_trylock_t *: ({ \
lockdep_assert(tl->acquired == 0); \
WRITE_ONCE(tl->acquired, 1); \
}), \
- __percpu local_lock_t *: (void)0); \
+ local_lock_t *: (void)0); \
local_lock_acquire(l); \
} while (0)
@@ -133,7 +133,7 @@ do { \
local_trylock_t *tl; \
\
preempt_disable(); \
- tl = this_cpu_ptr(lock); \
+ tl = (lock); \
if (READ_ONCE(tl->acquired)) { \
preempt_enable(); \
tl = NULL; \
@@ -150,7 +150,7 @@ do { \
local_trylock_t *tl; \
\
local_irq_save(flags); \
- tl = this_cpu_ptr(lock); \
+ tl = (lock); \
if (READ_ONCE(tl->acquired)) { \
local_irq_restore(flags); \
tl = NULL; \
@@ -167,15 +167,15 @@ do { \
local_trylock_t *tl; \
local_lock_t *l; \
\
- l = (local_lock_t *)this_cpu_ptr(lock); \
+ l = (local_lock_t *)(lock); \
tl = (local_trylock_t *)l; \
local_lock_release(l); \
_Generic((lock), \
- __percpu local_trylock_t *: ({ \
+ local_trylock_t *: ({ \
lockdep_assert(tl->acquired == 1); \
WRITE_ONCE(tl->acquired, 0); \
}), \
- __percpu local_lock_t *: (void)0); \
+ local_lock_t *: (void)0); \
} while (0)
#define __local_unlock(lock) \
@@ -199,11 +199,11 @@ do { \
#define __local_lock_nested_bh(lock) \
do { \
lockdep_assert_in_softirq(); \
- local_lock_acquire(this_cpu_ptr(lock)); \
+ local_lock_acquire((lock)); \
} while (0)
#define __local_unlock_nested_bh(lock) \
- local_lock_release(this_cpu_ptr(lock))
+ local_lock_release((lock))
#else /* !CONFIG_PREEMPT_RT */
@@ -227,7 +227,7 @@ typedef spinlock_t local_trylock_t;
#define __local_lock(__lock) \
do { \
migrate_disable(); \
- spin_lock(this_cpu_ptr((__lock))); \
+ spin_lock((__lock)); \
} while (0)
#define __local_lock_irq(lock) __local_lock(lock)
@@ -241,7 +241,7 @@ typedef spinlock_t local_trylock_t;
#define __local_unlock(__lock) \
do { \
- spin_unlock(this_cpu_ptr((__lock))); \
+ spin_unlock((__lock)); \
migrate_enable(); \
} while (0)
@@ -252,12 +252,12 @@ typedef spinlock_t local_trylock_t;
#define __local_lock_nested_bh(lock) \
do { \
lockdep_assert_in_softirq_func(); \
- spin_lock(this_cpu_ptr(lock)); \
+ spin_lock((lock)); \
} while (0)
#define __local_unlock_nested_bh(lock) \
do { \
- spin_unlock(this_cpu_ptr((lock))); \
+ spin_unlock((lock)); \
} while (0)
#define __local_trylock(lock) \
@@ -268,7 +268,7 @@ do { \
__locked = 0; \
} else { \
migrate_disable(); \
- __locked = spin_trylock(this_cpu_ptr((lock))); \
+ __locked = spin_trylock((lock)); \
if (!__locked) \
migrate_enable(); \
} \
--
2.49.0On Wed, May 14, 2025 at 4:07 AM Sebastian Andrzej Siewior
<bigeasy@linutronix.de> wrote:
>
> The local_lock.h is the main entry for the local_lock_t type and
> provides wrappers around internal functions prefixed with __ in
> local_lock_internal.h.
>
> Move the this_cpu_ptr() dereference of the variable from the internal to
> the main header. Since it is all macro implemented, this_cpu_ptr() will
> still happen within the preempt/ IRQ disabled section.
> This will free the internal implementation (__) to be used on
> local_lock_t types which are local variables and must not be accessed
> via this_cpu_ptr().
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
> include/linux/local_lock.h | 20 +++++++++----------
> include/linux/local_lock_internal.h | 30 ++++++++++++++---------------
> 2 files changed, 25 insertions(+), 25 deletions(-)
>
> diff --git a/include/linux/local_lock.h b/include/linux/local_lock.h
> index 16a2ee4f8310b..2ba8464195244 100644
> --- a/include/linux/local_lock.h
> +++ b/include/linux/local_lock.h
> @@ -13,13 +13,13 @@
> * local_lock - Acquire a per CPU local lock
> * @lock: The lock variable
> */
> -#define local_lock(lock) __local_lock(lock)
> +#define local_lock(lock) __local_lock(this_cpu_ptr(lock))
>
> /**
> * local_lock_irq - Acquire a per CPU local lock and disable interrupts
> * @lock: The lock variable
> */
> -#define local_lock_irq(lock) __local_lock_irq(lock)
> +#define local_lock_irq(lock) __local_lock_irq(this_cpu_ptr(lock))
>
> /**
> * local_lock_irqsave - Acquire a per CPU local lock, save and disable
> @@ -28,19 +28,19 @@
> * @flags: Storage for interrupt flags
> */
> #define local_lock_irqsave(lock, flags) \
> - __local_lock_irqsave(lock, flags)
> + __local_lock_irqsave(this_cpu_ptr(lock), flags)
>
> /**
> * local_unlock - Release a per CPU local lock
> * @lock: The lock variable
> */
> -#define local_unlock(lock) __local_unlock(lock)
> +#define local_unlock(lock) __local_unlock(this_cpu_ptr(lock))
>
> /**
> * local_unlock_irq - Release a per CPU local lock and enable interrupts
> * @lock: The lock variable
> */
> -#define local_unlock_irq(lock) __local_unlock_irq(lock)
> +#define local_unlock_irq(lock) __local_unlock_irq(this_cpu_ptr(lock))
>
> /**
> * local_unlock_irqrestore - Release a per CPU local lock and restore
> @@ -49,7 +49,7 @@
> * @flags: Interrupt flags to restore
> */
> #define local_unlock_irqrestore(lock, flags) \
> - __local_unlock_irqrestore(lock, flags)
> + __local_unlock_irqrestore(this_cpu_ptr(lock), flags)
>
> /**
> * local_lock_init - Runtime initialize a lock instance
> @@ -64,7 +64,7 @@
> * locking constrains it will _always_ fail to acquire the lock in NMI or
> * HARDIRQ context on PREEMPT_RT.
> */
> -#define local_trylock(lock) __local_trylock(lock)
> +#define local_trylock(lock) __local_trylock(this_cpu_ptr(lock))
>
> /**
> * local_trylock_irqsave - Try to acquire a per CPU local lock, save and disable
> @@ -77,7 +77,7 @@
> * HARDIRQ context on PREEMPT_RT.
> */
> #define local_trylock_irqsave(lock, flags) \
> - __local_trylock_irqsave(lock, flags)
> + __local_trylock_irqsave(this_cpu_ptr(lock), flags)
>
> DEFINE_GUARD(local_lock, local_lock_t __percpu*,
> local_lock(_T),
> @@ -91,10 +91,10 @@ DEFINE_LOCK_GUARD_1(local_lock_irqsave, local_lock_t __percpu,
> unsigned long flags)
>
> #define local_lock_nested_bh(_lock) \
> - __local_lock_nested_bh(_lock)
> + __local_lock_nested_bh(this_cpu_ptr(_lock))
>
> #define local_unlock_nested_bh(_lock) \
> - __local_unlock_nested_bh(_lock)
> + __local_unlock_nested_bh(this_cpu_ptr(_lock))
>
> DEFINE_GUARD(local_lock_nested_bh, local_lock_t __percpu*,
> local_lock_nested_bh(_T),
> diff --git a/include/linux/local_lock_internal.h b/include/linux/local_lock_internal.h
> index 8d5ac16a9b179..b4d7b24882835 100644
> --- a/include/linux/local_lock_internal.h
> +++ b/include/linux/local_lock_internal.h
> @@ -99,14 +99,14 @@ do { \
> local_trylock_t *tl; \
> local_lock_t *l; \
> \
> - l = (local_lock_t *)this_cpu_ptr(lock); \
> + l = (local_lock_t *)(lock); \
> tl = (local_trylock_t *)l; \
> _Generic((lock), \
> - __percpu local_trylock_t *: ({ \
> + local_trylock_t *: ({ \
> lockdep_assert(tl->acquired == 0); \
> WRITE_ONCE(tl->acquired, 1); \
> }), \
> - __percpu local_lock_t *: (void)0); \
> + local_lock_t *: (void)0); \
Are you sure this is correct?
Have you tested with gcc 14 or higher?
It looks to me that moving this_cpu_ptr() up one level should
still preserve __seg_gs modifier.
On 2025-05-14 17:46:43 [-0700], Alexei Starovoitov wrote:
>
> Are you sure this is correct?
I hope so.
> Have you tested with gcc 14 or higher?
gcc version 14.2.0 (Debian 14.2.0-19)
> It looks to me that moving this_cpu_ptr() up one level should
> still preserve __seg_gs modifier.
If I compile mm/memcontrol.o as-is I get no warnings. Adding
diff --git a/include/linux/local_lock_internal.h b/include/linux/local_lock_internal.h
index b4d7b24882835..112324bc362c1 100644
--- a/include/linux/local_lock_internal.h
+++ b/include/linux/local_lock_internal.h
@@ -102,11 +102,11 @@ do { \
l = (local_lock_t *)(lock); \
tl = (local_trylock_t *)l; \
_Generic((lock), \
- local_trylock_t *: ({ \
+ __percpu local_trylock_t *: ({ \
lockdep_assert(tl->acquired == 0); \
WRITE_ONCE(tl->acquired, 1); \
}), \
- local_lock_t *: (void)0); \
+ __percpu local_lock_t *: (void)0); \
local_lock_acquire(l); \
} while (0)
@@ -171,11 +171,11 @@ do { \
tl = (local_trylock_t *)l; \
local_lock_release(l); \
_Generic((lock), \
- local_trylock_t *: ({ \
+ __percpu local_trylock_t *: ({ \
lockdep_assert(tl->acquired == 1); \
WRITE_ONCE(tl->acquired, 0); \
}), \
- local_lock_t *: (void)0); \
+ __percpu local_lock_t *: (void)0); \
} while (0)
#define __local_unlock(lock) \
which I assume is what you mean, results in
| In file included from include/linux/preempt.h:11,
| from include/linux/spinlock.h:56,
| from include/linux/swait.h:7,
| from include/linux/completion.h:12,
| from include/linux/crypto.h:15,
| from arch/x86/kernel/asm-offsets.c:9:
| include/linux/local_lock.h: In function ‘class_local_lock_destructor’:
| include/linux/local_lock_internal.h:173:26: error: ‘_Generic’ selector of type ‘struct <anonymous> *’ is not compatible with any association
| 173 | _Generic((lock), \
| | ^
| include/linux/cleanup.h:246:18: note: in definition of macro ‘DEFINE_CLASS’
| 246 | { _type _T = *p; _exit; } \
| | ^~~~~
| include/linux/local_lock.h:82:1: note: in expansion of macro ‘DEFINE_GUARD’
| 82 | DEFINE_GUARD(local_lock, local_lock_t __percpu*,
| | ^~~~~~~~~~~~
| include/linux/local_lock_internal.h:183:17: note: in expansion of macro ‘__local_lock_release’
| 183 | __local_lock_release(lock); \
| | ^~~~~~~~~~~~~~~~~~~~
| include/linux/local_lock.h:37:41: note: in expansion of macro ‘__local_unlock’
| 37 | #define local_unlock(lock) __local_unlock(this_cpu_ptr(lock))
| | ^~~~~~~~~~~~~~
| include/linux/local_lock.h:84:14: note: in expansion of macro ‘local_unlock’
| 84 | local_unlock(_T))
| | ^~~~~~~~~~~~
| include/linux/local_lock.h: In function ‘class_local_lock_constructor’:
| include/linux/local_lock_internal.h:104:26: error: ‘_Generic’ selector of type ‘struct <anonymous> *’ is not compatible with any association
| 104 | _Generic((lock), \
| | ^
| include/linux/cleanup.h:248:13: note: in definition of macro ‘DEFINE_CLASS’
| 248 | { _type t = _init; return t; }
| | ^~~~~
| include/linux/local_lock.h:82:1: note: in expansion of macro ‘DEFINE_GUARD’
| 82 | DEFINE_GUARD(local_lock, local_lock_t __percpu*,
| | ^~~~~~~~~~~~
| include/linux/local_lock_internal.h:116:17: note: in expansion of macro ‘__local_lock_acquire’
| 116 | __local_lock_acquire(lock); \
| | ^~~~~~~~~~~~~~~~~~~~
| include/linux/local_lock.h:16:41: note: in expansion of macro ‘__local_lock’
| 16 | #define local_lock(lock) __local_lock(this_cpu_ptr(lock))
…
Sebastian
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