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Make kmutex_t typesafe in all cases.
When HAVE_MUTEX_OWNER and CONFIG_SMP are defined, kmutex_t is just a typedef for struct mutex. This is generally OK but has the downside that it can make mistakes such as mutex_lock(&kmutex_var) to pass by unnoticed until someone compiles the code without HAVE_MUTEX_OWNER or CONFIG_SMP (in which case kmutex_t is a real struct). Note that the correct API to call should have been mutex_enter() rather than mutex_lock(). We prevent these kind of mistakes by making kmutex_t a real structure with only one field. This makes kmutex_t typesafe and it shouldn't have any impact on the generated assembly code. Signed-off-by: Ricardo M. Correia <ricardo.correia@oracle.com> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
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@ -37,14 +37,20 @@ typedef enum {
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#if defined(HAVE_MUTEX_OWNER) && defined(CONFIG_SMP)
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typedef struct mutex kmutex_t;
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/*
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* We define a 1-field struct rather than a straight typedef to enforce type
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* safety.
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*/
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typedef struct {
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struct mutex m;
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} kmutex_t;
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static inline kthread_t *
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mutex_owner(kmutex_t *mp)
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{
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struct thread_info *owner;
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struct thread_info *owner;
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owner = ACCESS_ONCE(mp->owner);
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owner = ACCESS_ONCE(mp->m.owner);
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if (owner)
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return owner->task;
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@ -54,7 +60,7 @@ mutex_owner(kmutex_t *mp)
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static inline int
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mutex_owned(kmutex_t *mp)
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{
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return (ACCESS_ONCE(mp->owner) == current_thread_info());
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return (ACCESS_ONCE(mp->m.owner) == current_thread_info());
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}
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#define MUTEX_HELD(mp) mutex_owned(mp)
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@ -65,31 +71,31 @@ mutex_owned(kmutex_t *mp)
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static struct lock_class_key __key; \
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ASSERT(type == MUTEX_DEFAULT); \
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\
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__mutex_init((mp), #mp, &__key); \
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__mutex_init(&(mp)->m, #mp, &__key); \
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})
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#undef mutex_destroy
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#define mutex_destroy(mp) \
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({ \
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VERIFY3P(mutex_owner(mp), ==, NULL); \
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VERIFY3P(mutex_owner(mp), ==, NULL); \
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})
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#define mutex_tryenter(mp) mutex_trylock(mp)
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#define mutex_enter(mp) mutex_lock(mp)
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#define mutex_tryenter(mp) mutex_trylock(&(mp)->m)
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#define mutex_enter(mp) mutex_lock(&(mp)->m)
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/* mutex->owner is not cleared when CONFIG_DEBUG_MUTEXES is set */
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#ifdef CONFIG_DEBUG_MUTEXES
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# define mutex_exit(mp) \
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({ \
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mutex_unlock(mp); \
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(mp)->owner = NULL; \
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mutex_unlock(&(mp)->m); \
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(mp)->m.owner = NULL; \
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})
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#else
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# define mutex_exit(mp) mutex_unlock(mp)
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# define mutex_exit(mp) mutex_unlock(&(mp)->m)
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#endif /* CONFIG_DEBUG_MUTEXES */
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#ifdef HAVE_GPL_ONLY_SYMBOLS
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# define mutex_enter_nested(mp, sc) mutex_lock_nested(mp, sc)
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# define mutex_enter_nested(mp, sc) mutex_lock_nested(&(mp)->m, sc)
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#else
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# define mutex_enter_nested(mp, sc) mutex_enter(mp)
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#endif /* HAVE_GPL_ONLY_SYMBOLS */
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@ -172,7 +178,7 @@ mutex_owner(kmutex_t *mp)
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#undef mutex_destroy
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#define mutex_destroy(mp) \
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({ \
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VERIFY3P(mutex_owner(mp), ==, NULL); \
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VERIFY3P(mutex_owner(mp), ==, NULL); \
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})
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#define mutex_tryenter(mp) \
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