内核配置改变导致的panic

经常会因为内核配置改动了一下，从新编译内核后，如果加载以前的驱动，会导致一些错误。

有时甚者内核挂了。

 

以前就从新编译一下驱动就完事，但是没深究。

几天看了mutex的实现，呵呵，看到了原因。

 

如下：

 

struct mutex {
        /* 1: unlocked, 0: locked, negative: locked, possible waiters */
        atomic_t                count;
        spinlock_t              wait_lock;
        struct list_head        wait_list;
#ifdef CONFIG_DEBUG_MUTEXES
        struct thread_info      *owner;
        const char              *name;
        void                    *magic;
#endif
#ifdef CONFIG_DEBUG_LOCK_ALLOC
        struct lockdep_map      dep_map;
#endif
};

 

内核的配置不同，会有以下四种结果：

如果，驱动在CONFIG_DEBUG_MUTEXES跟CONFIG_DEBUG_LOCK_ALLOC都没配置的情况下编译，但是后来内核将CONFIG_DEBUG_MUTEXES跟CONFIG_DEBUG_LOCK_ALLOC都加上，那么，肯定会越界访问了。

 

struct mutex {
        /* 1: unlocked, 0: locked, negative: locked, possible waiters */
        atomic_t                count;
        spinlock_t              wait_lock;
        struct list_head        wait_list;
};

 

struct mutex {
        /* 1: unlocked, 0: locked, negative: locked, possible waiters */
        atomic_t                count;
        spinlock_t              wait_lock;
        struct list_head        wait_list;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
        struct lockdep_map      dep_map;
#endif
};

 

struct mutex {
        /* 1: unlocked, 0: locked, negative: locked, possible waiters */
        atomic_t                count;
        spinlock_t              wait_lock;
        struct list_head        wait_list;
#ifdef CONFIG_DEBUG_MUTEXES
        struct thread_info      *owner;
        const char              *name;
        void                    *magic;
#endif
};

 

struct mutex {
        /* 1: unlocked, 0: locked, negative: locked, possible waiters */
        atomic_t                count;
        spinlock_t              wait_lock;
        struct list_head        wait_list;
#ifdef CONFIG_DEBUG_MUTEXES
        struct thread_info      *owner;
        const char              *name;
        void                    *magic;
#endif
#ifdef CONFIG_DEBUG_LOCK_ALLOC
        struct lockdep_map      dep_map;
#endif
};

 

如果改变你内核的配置，最好从新编译一下你的驱动！！！