raw_spin_lock_irqsave() flow

raw_spin_lock_irqsave() flow

include/linux/spinlock.h

#define raw_spin_lock_irqsave(lock, flags)            
    do {                        
        typecheck(unsigned long, flags);    
        flags = _raw_spin_lock_irqsave(lock);    
    } while (0)

static inline unsigned long __raw_spin_lock_irqsave(raw_spinlock_t *lock)

static inline void
do_raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long *flags) __acquires(lock)
{
    __acquire(lock);
    arch_spin_lock_flags(&lock->raw_lock, *flags);
}

上面raw_lock是：

arch_spinlock_t raw_lock;

arch_spinlock_t为qspinlock：

typedef struct qspinlock {
    union {
        atomic_t val;

        /*
         * By using the whole 2nd least significant byte for the
         * pending bit, we can allow better optimization of the lock
         * acquisition for the pending bit holder.
         */
#ifdef __LITTLE_ENDIAN
        struct {
            u8    locked;
            u8    pending;
        };
        struct {
            u16    locked_pending;
            u16    tail;
        };
#else
        struct {
            u16    tail;
            u16    locked_pending;
        };
        struct {
            u8    reserved[2];
            u8    pending;
            u8    locked;
        };
#endif
    };
} arch_spinlock_t;

上面arch_spin_lock_flags define为arch_spin_lock()，这个define在qspinlock.h

#ifndef arch_spin_lock_flags
#define arch_spin_lock_flags(lock, flags)    arch_spin_lock(lock)
#endif

4.19includeasm-genericQspinlock.h

#define arch_spin_lock(l)        queued_spin_lock(l)