spin_lock_irqsave() guaranteed that only an uninterrupted CPU execute the
code protected by the lock.
See at this implementation ( optimization = 0.0 ) :
struct s_nested_lock {
spinlock_t lock;
short int pid;
short int count;
};
#define nested_lock(lock, flags) \
if (lock->pid == getpid()) { \
++lock->count; \
} else { \
spin_lock_irqsave(&lock->lock, flags); \
lock->pid = getpid(); \
}
#define nested_unlock(lock, flags) \
if (--lock->count == 0) { \
lock->pid = 0; \
spin_unlock_irqrestore(&lock->lock, flags); \
}
Cheers,
Davide.
-- "Debian, the Freedom in Freedom."
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