[PATCH 01/11] tty/sysrq: alpha: export and use __sysrq_get_key_op()

Emil Velikov
2020-05-13T21:46:42Z

Export a pointer to the sysrq_get_key_op(). This way we can cleanly
unregister it, instead of the current solutions of modifuing it inplace.

Since __sysrq_get_key_op() is no longer used externally, let's make it
a static function.

This patch will allow us to limit access to each and every sysrq op and
constify the sysrq handling.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-kernel@vger.kernel.org
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: linux-alpha@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.
---
arch/alpha/kernel/setup.c | 13 +++++++++++--
drivers/tty/sysrq.c | 4 +++-
include/linux/sysrq.h | 2 +-
3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/arch/alpha/kernel/setup.c b/arch/alpha/kernel/setup.c
index f19aa577354b..dd7f770f23cf 100644
--- a/arch/alpha/kernel/setup.c
+++ b/arch/alpha/kernel/setup.c
@@ -430,6 +430,15 @@ register_cpus(void)

arch_initcall(register_cpus);

+#ifdef CONFIG_MAGIC_SYSRQ
+static struct sysrq_key_op srm_sysrq_reboot_op = {
+ .handler = machine_halt,
+ .help_msg = "reboot(b)",
+ .action_msg = "Resetting",
+ .enable_mask = SYSRQ_ENABLE_BOOT,
+};
+#endif
+
void __init
setup_arch(char **cmdline_p)
{
@@ -550,8 +559,8 @@ setup_arch(char **cmdline_p)
/* If we're using SRM, make sysrq-b halt back to the prom,
not auto-reboot. */
if (alpha_using_srm) {
- struct sysrq_key_op *op = __sysrq_get_key_op('b');
- op->handler = (void *) machine_halt;
+ unregister_sysrq_key('b', __sysrq_reboot_op);
+ register_sysrq_key('b', &srm_sysrq_reboot_op);
}
#endif

diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
index 0dc3878794fd..1741134cabca 100644
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -172,6 +172,8 @@ static struct sysrq_key_op sysrq_reboot_op = {
.enable_mask = SYSRQ_ENABLE_BOOT,
};

+struct sysrq_key_op *__sysrq_reboot_op = &sysrq_reboot_op;
+
static void sysrq_handle_sync(int key)
{
emergency_sync();
@@ -516,7 +518,7 @@ static int sysrq_key_table_key2index(int key)
/*
* get and put functions for the table, exposed to modules.
*/
-struct sysrq_key_op *__sysrq_get_key_op(int key)
+static struct sysrq_key_op *__sysrq_get_key_op(int key)
{
struct sysrq_key_op *op_p = NULL;
int i;
diff --git a/include/linux/sysrq.h b/include/linux/sysrq.h
index 8e159e16850f..9b51f98e5f60 100644
--- a/include/linux/sysrq.h
+++ b/include/linux/sysrq.h
@@ -47,7 +47,7 @@ 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);
-struct sysrq_key_op *__sysrq_get_key_op(int key);
+extern struct sysrq_key_op *__sysrq_reboot_op;

int sysrq_toggle_support(int enable_mask);
int sysrq_mask(void);
--
2.25.1