Messages in this thread Patch in this message | | | From | David Kilroy <> | Subject | [PATCH v2] check spinlock_t/rwlock_t argument type on non-SMP builds | Date | Wed, 22 Jul 2009 19:11:35 +0100 |
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When writing code for UP without CONFIG_DEBUG_SPINLOCK it's easy to get the first argument to the spinlock/rwlock functions wrong. This is because the parameter is not actually used in this configuration.
Typically you will only find out it's wrong * by rebuilding with CONFIG_SMP or CONFIG_DEBUG_SPINLOCK * after you've submitted your beautiful patch series.
The first means a long wait, and the latter is a bit late.
Change the intermediate macros into inline functions.
Signed-off-by: David Kilroy <kilroyd@googlemail.com> Cc: Ingo Molnar <mingo@elte.hu> ---
The previous version of this patch achieved the typechecking by explicitly calling typecheck() within the macros. This version, at the behest of Ingo, turns the macros into proper C functions. One benefit of this is that the compiler no longer complains about how net/ipv4/route.c passes NULL into spinlock_xx()
I've made the functions static inline, so there should be minimal impact on generated code (assuming the compiler is listening). I haven't done any comparisons yet.
In an allyesconfig build, compiler warnings are unchanged. One side-effect of this is that sparse (with -Wcontext) reports certain locking errors against spinlock_api_up.h instead of the file containing the function doing the spinlock call. For example:
CHECK kernel/rtmutex.c kernel/rtmutex.c:149:5: warning: symbol 'max_lock_depth' was not declared. Should it be static? kernel/rtmutex.c:291:2: warning: context imbalance in 'rt_mutex_adjust_prio_chain' - different lock contexts for basic block kernel/rtmutex.c:675:3: warning: context imbalance in '__rt_mutex_slowlock' - unexpected unlock kernel/rtmutex.c:1029:5: warning: context imbalance in 'rt_mutex_start_proxy_lock' - wrong count at exit CC kernel/rtmutex.o
becomes...
CHECK kernel/rtmutex.c kernel/rtmutex.c:149:5: warning: symbol 'max_lock_depth' was not declared. Should it be static? kernel/rtmutex.c:291:2: warning: context imbalance in 'rt_mutex_adjust_prio_chain' - different lock contexts for basic block include/linux/spinlock_api_up.h:103:3: warning: context imbalance in '__rt_mutex_slowlock' - unexpected unlock kernel/rtmutex.c:1029:5: warning: context imbalance in 'rt_mutex_start_proxy_lock' - wrong count at exit CC kernel/rtmutex.o
This might just be my version of sparse. I tried adding the __acquires() tag to the inline functions, but sparse didn't behave any differently.
Ingo - is this what you were thinking of?
Thanks,
Dave.
--- include/linux/spinlock.h | 6 +- include/linux/spinlock_api_up.h | 118 +++++++++++++++++++++++++++++---------- 2 files changed, 92 insertions(+), 32 deletions(-)
diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index 252b245..6462de1 100644 --- a/include/linux/spinlock.h +++ b/include/linux/spinlock.h @@ -244,17 +244,17 @@ do { \ #define spin_lock_irqsave(lock, flags) \ do { \ typecheck(unsigned long, flags); \ - _spin_lock_irqsave(lock, flags); \ + _spin_lock_irqsave(lock, &flags); \ } while (0) #define read_lock_irqsave(lock, flags) \ do { \ typecheck(unsigned long, flags); \ - _read_lock_irqsave(lock, flags); \ + _read_lock_irqsave(lock, &flags); \ } while (0) #define write_lock_irqsave(lock, flags) \ do { \ typecheck(unsigned long, flags); \ - _write_lock_irqsave(lock, flags); \ + _write_lock_irqsave(lock, &flags); \ } while (0) #define spin_lock_irqsave_nested(lock, flags, subclass) \ spin_lock_irqsave(lock, flags) diff --git a/include/linux/spinlock_api_up.h b/include/linux/spinlock_api_up.h index 04e1d31..ed9197d 100644 --- a/include/linux/spinlock_api_up.h +++ b/include/linux/spinlock_api_up.h @@ -48,34 +48,94 @@ #define __UNLOCK_IRQRESTORE(lock, flags) \ do { local_irq_restore(flags); __UNLOCK(lock); } while (0) -#define _spin_lock(lock) __LOCK(lock) -#define _spin_lock_nested(lock, subclass) __LOCK(lock) -#define _read_lock(lock) __LOCK(lock) -#define _write_lock(lock) __LOCK(lock) -#define _spin_lock_bh(lock) __LOCK_BH(lock) -#define _read_lock_bh(lock) __LOCK_BH(lock) -#define _write_lock_bh(lock) __LOCK_BH(lock) -#define _spin_lock_irq(lock) __LOCK_IRQ(lock) -#define _read_lock_irq(lock) __LOCK_IRQ(lock) -#define _write_lock_irq(lock) __LOCK_IRQ(lock) -#define _spin_lock_irqsave(lock, flags) __LOCK_IRQSAVE(lock, flags) -#define _read_lock_irqsave(lock, flags) __LOCK_IRQSAVE(lock, flags) -#define _write_lock_irqsave(lock, flags) __LOCK_IRQSAVE(lock, flags) -#define _spin_trylock(lock) ({ __LOCK(lock); 1; }) -#define _read_trylock(lock) ({ __LOCK(lock); 1; }) -#define _write_trylock(lock) ({ __LOCK(lock); 1; }) -#define _spin_trylock_bh(lock) ({ __LOCK_BH(lock); 1; }) -#define _spin_unlock(lock) __UNLOCK(lock) -#define _read_unlock(lock) __UNLOCK(lock) -#define _write_unlock(lock) __UNLOCK(lock) -#define _spin_unlock_bh(lock) __UNLOCK_BH(lock) -#define _write_unlock_bh(lock) __UNLOCK_BH(lock) -#define _read_unlock_bh(lock) __UNLOCK_BH(lock) -#define _spin_unlock_irq(lock) __UNLOCK_IRQ(lock) -#define _read_unlock_irq(lock) __UNLOCK_IRQ(lock) -#define _write_unlock_irq(lock) __UNLOCK_IRQ(lock) -#define _spin_unlock_irqrestore(lock, flags) __UNLOCK_IRQRESTORE(lock, flags) -#define _read_unlock_irqrestore(lock, flags) __UNLOCK_IRQRESTORE(lock, flags) -#define _write_unlock_irqrestore(lock, flags) __UNLOCK_IRQRESTORE(lock, flags) +static inline void _spin_lock(spinlock_t *lock) +{ __LOCK(lock); } + +static inline void _spin_lock_nested(spinlock_t *lock, int subclass) +{ __LOCK(lock); } + +static inline void _read_lock(rwlock_t *lock) +{ __LOCK(lock); } + +static inline void _write_lock(rwlock_t *lock) +{ __LOCK(lock); } + +static inline void _spin_lock_bh(spinlock_t *lock) +{ __LOCK_BH(lock); } + +static inline void _read_lock_bh(rwlock_t *lock) +{ __LOCK_BH(lock); } + +static inline void _write_lock_bh(rwlock_t *lock) +{ __LOCK_BH(lock); } + +static inline void _spin_lock_irq(spinlock_t *lock) +{ __LOCK_IRQ(lock); } + +static inline void _read_lock_irq(rwlock_t *lock) +{ __LOCK_IRQ(lock); } + +static inline void _write_lock_irq(rwlock_t *lock) +{ __LOCK_IRQ(lock); } + +static inline void _spin_lock_irqsave(spinlock_t *lock, unsigned long *flags) +{ __LOCK_IRQSAVE(lock, *flags); } + +static inline void _read_lock_irqsave(rwlock_t *lock, unsigned long *flags) +{ __LOCK_IRQSAVE(lock, *flags); } + +static inline void _write_lock_irqsave(rwlock_t *lock, unsigned long *flags) +{ __LOCK_IRQSAVE(lock, *flags); } + +static inline int _spin_trylock(spinlock_t *lock) +{ __LOCK(lock); return 1; } + +static inline int _read_trylock(rwlock_t *lock) +{ __LOCK(lock); return 1; } + +static inline int _write_trylock(rwlock_t *lock) +{ __LOCK(lock); return 1; } + +static inline int _spin_trylock_bh(spinlock_t *lock) +{ __LOCK(lock); return 1; } + +static inline void _spin_unlock(spinlock_t *lock) +{ __UNLOCK(lock); } + +static inline void _read_unlock(rwlock_t *lock) +{ __UNLOCK(lock); } + +static inline void _write_unlock(rwlock_t *lock) +{ __UNLOCK(lock); } + +static inline void _spin_unlock_bh(spinlock_t *lock) +{ __UNLOCK_BH(lock); } + +static inline void _read_unlock_bh(rwlock_t *lock) +{ __UNLOCK_BH(lock); } + +static inline void _write_unlock_bh(rwlock_t *lock) +{ __UNLOCK_BH(lock); } + +static inline void _spin_unlock_irq(spinlock_t *lock) +{ __UNLOCK_IRQ(lock); } + +static inline void _read_unlock_irq(rwlock_t *lock) +{ __UNLOCK_IRQ(lock); } + +static inline void _write_unlock_irq(rwlock_t *lock) +{ __UNLOCK_IRQ(lock); } + +static inline void _spin_unlock_irqrestore(spinlock_t *lock, + unsigned long flags) +{ __UNLOCK_IRQRESTORE(lock, flags); } + +static inline void _read_unlock_irqrestore(rwlock_t *lock, + unsigned long flags) +{ __UNLOCK_IRQRESTORE(lock, flags); } + +static inline void _write_unlock_irqrestore(rwlock_t *lock, + unsigned long flags) +{ __UNLOCK_IRQRESTORE(lock, flags); } #endif /* __LINUX_SPINLOCK_API_UP_H */ -- 1.6.3.3
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