The user is not supposed to thinker with the underlying sysrq_key_op. Make that explicit by adding a handful of const notations.
Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Jiri Slaby jslaby@suse.com Cc: linux-kernel@vger.kernel.org Signed-off-by: Emil Velikov emil.l.velikov@gmail.com --- Please keep me in the CC list, as I'm not subscribed to the list.
IMHO it would be better if this gets merged this via the tty tree. --- Documentation/admin-guide/sysrq.rst | 10 +++++----- drivers/tty/sysrq.c | 16 ++++++++-------- include/linux/sysrq.h | 16 ++++++++-------- 3 files changed, 21 insertions(+), 21 deletions(-)
diff --git a/Documentation/admin-guide/sysrq.rst b/Documentation/admin-guide/sysrq.rst index a46209f4636c..e6424d8c5846 100644 --- a/Documentation/admin-guide/sysrq.rst +++ b/Documentation/admin-guide/sysrq.rst @@ -231,13 +231,13 @@ prints help, and C) an action_msg string, that will print right before your handler is called. Your handler must conform to the prototype in 'sysrq.h'.
After the ``sysrq_key_op`` is created, you can call the kernel function -``register_sysrq_key(int key, struct sysrq_key_op *op_p);`` this will +``register_sysrq_key(int key, const struct sysrq_key_op *op_p);`` this will register the operation pointed to by ``op_p`` at table key 'key', if that slot in the table is blank. At module unload time, you must call -the function ``unregister_sysrq_key(int key, struct sysrq_key_op *op_p)``, which -will remove the key op pointed to by 'op_p' from the key 'key', if and only if -it is currently registered in that slot. This is in case the slot has been -overwritten since you registered it. +the function ``unregister_sysrq_key(int key, const struct sysrq_key_op *op_p)``, +which will remove the key op pointed to by 'op_p' from the key 'key', if and +only if it is currently registered in that slot. This is in case the slot has +been overwritten since you registered it.
The Magic SysRQ system works by registering key operations against a key op lookup table, which is defined in 'drivers/tty/sysrq.c'. This key table has diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index 1741134cabca..091c64a3cef0 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -518,9 +518,9 @@ static int sysrq_key_table_key2index(int key) /* * get and put functions for the table, exposed to modules. */ -static struct sysrq_key_op *__sysrq_get_key_op(int key) +static const struct sysrq_key_op *__sysrq_get_key_op(int key) { - struct sysrq_key_op *op_p = NULL; + const struct sysrq_key_op *op_p = NULL; int i;
i = sysrq_key_table_key2index(key); @@ -530,7 +530,7 @@ static struct sysrq_key_op *__sysrq_get_key_op(int key) return op_p; }
-static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p) +static void __sysrq_put_key_op(int key, const struct sysrq_key_op *op_p) { int i = sysrq_key_table_key2index(key);
@@ -540,7 +540,7 @@ static void __sysrq_put_key_op(int key, struct sysrq_key_op *op_p)
void __handle_sysrq(int key, bool check_mask) { - struct sysrq_key_op *op_p; + const struct sysrq_key_op *op_p; int orig_log_level; int orig_suppress_printk; int i; @@ -1063,8 +1063,8 @@ int sysrq_toggle_support(int enable_mask) } EXPORT_SYMBOL_GPL(sysrq_toggle_support);
-static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p, - struct sysrq_key_op *remove_op_p) +static int __sysrq_swap_key_ops(int key, const struct sysrq_key_op *insert_op_p, + const struct sysrq_key_op *remove_op_p) { int retval;
@@ -1087,13 +1087,13 @@ static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p, return retval; }
-int register_sysrq_key(int key, struct sysrq_key_op *op_p) +int register_sysrq_key(int key, const struct sysrq_key_op *op_p) { return __sysrq_swap_key_ops(key, op_p, NULL); } EXPORT_SYMBOL(register_sysrq_key);
-int unregister_sysrq_key(int key, struct sysrq_key_op *op_p) +int unregister_sysrq_key(int key, const struct sysrq_key_op *op_p) { return __sysrq_swap_key_ops(key, NULL, op_p); } diff --git a/include/linux/sysrq.h b/include/linux/sysrq.h index 9b51f98e5f60..479028391c08 100644 --- a/include/linux/sysrq.h +++ b/include/linux/sysrq.h @@ -30,10 +30,10 @@ #define SYSRQ_ENABLE_RTNICE 0x0100
struct sysrq_key_op { - void (*handler)(int); - char *help_msg; - char *action_msg; - int enable_mask; + void (* const handler)(int); + const char * const help_msg; + const char * const action_msg; + const int enable_mask; };
#ifdef CONFIG_MAGIC_SYSRQ @@ -45,8 +45,8 @@ struct sysrq_key_op {
void handle_sysrq(int key); void __handle_sysrq(int key, bool check_mask); -int register_sysrq_key(int key, struct sysrq_key_op *op); -int unregister_sysrq_key(int key, struct sysrq_key_op *op); +int register_sysrq_key(int key, const struct sysrq_key_op *op); +int unregister_sysrq_key(int key, const struct sysrq_key_op *op); extern struct sysrq_key_op *__sysrq_reboot_op;
int sysrq_toggle_support(int enable_mask); @@ -62,12 +62,12 @@ static inline void __handle_sysrq(int key, bool check_mask) { }
-static inline int register_sysrq_key(int key, struct sysrq_key_op *op) +static inline int register_sysrq_key(int key, const struct sysrq_key_op *op) { return -EINVAL; }
-static inline int unregister_sysrq_key(int key, struct sysrq_key_op *op) +static inline int unregister_sysrq_key(int key, const struct sysrq_key_op *op) { return -EINVAL; }