From: "Mathieu J. Poirier" <mathieu.poirier@xxxxxxxxxx>
Some devices have too few buttons, which it makes it hard to have
a reset combo that won't trigger automatically. As such a
timeout functionality that requires the combination to be held for
a given amount of time before triggering is introduced.
If a key combo is recognized and held for a 'timeout' amount of time,
the system triggers a reset. If the timeout value is omitted the
driver simply ignores the functionality.
Signed-off-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
---
Changes for v4:
- Cancel timer if more keys are pressed after a valid combo.
- Trigger reset right away if timeout hasn't been set.
- Modifying miscellaneous names.
drivers/tty/sysrq.c | 55 ++++++++++++++++++++++++++++++++++++++-------------
1 file changed, 41 insertions(+), 14 deletions(-)
diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
index 7953dfa..766878a 100644
--- a/drivers/tty/sysrq.c
+++ b/drivers/tty/sysrq.c
@@ -42,6 +42,7 @@
#include <linux/input.h>
#include <linux/uaccess.h>
#include <linux/moduleparam.h>
+#include <linux/jiffies.h>
#include <asm/ptrace.h>
#include <asm/irq_regs.h>
@@ -50,6 +51,9 @@
static int __read_mostly sysrq_enabled = SYSRQ_DEFAULT_ENABLE;
static bool __read_mostly sysrq_always_enabled;
+unsigned short platform_sysrq_reset_seq[] __weak = { KEY_RESERVED };
+int sysrq_reset_downtime_ms __weak;
+
static bool sysrq_on(void)
{
return sysrq_enabled || sysrq_always_enabled;
@@ -584,6 +588,7 @@ struct sysrq_state {
int reset_seq_len;
int reset_seq_cnt;
int reset_seq_version;
+ struct timer_list keyreset_timer;
};
#define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */
@@ -617,29 +622,51 @@ static void sysrq_parse_reset_sequence(struct sysrq_state *state)
state->reset_seq_version = sysrq_reset_seq_version;
}
-static bool sysrq_detect_reset_sequence(struct sysrq_state *state,
+static void sysrq_do_reset(unsigned long dummy)
+{
+ __handle_sysrq(sysrq_xlate[KEY_B], false);
+}
+
+static void sysrq_handle_reset_request(struct sysrq_state *state)
+{
+ if (sysrq_reset_downtime_ms)
+ mod_timer(&state->keyreset_timer,
+ jiffies + msecs_to_jiffies(sysrq_reset_downtime_ms));
+ else
+ sysrq_do_reset(0);
+}
+
+static void sysrq_detect_reset_sequence(struct sysrq_state *state,
unsigned int code, int value)
{
if (!test_bit(code, state->reset_keybit)) {
/*
* Pressing any key _not_ in reset sequence cancels
- * the reset sequence.
+ * the reset sequence. Also cancelling the timer in
+ * case additional keys were pressed after a reset
+ * has been requested.
*/
- if (value && state->reset_seq_cnt)
+ if (value && state->reset_seq_cnt) {
state->reset_canceled = true;
+ del_timer(&state->keyreset_timer);
+ }
} else if (value == 0) {
- /* key release */
+ /*
+ * Key release - all keys in the reset sequence need
+ * to be pressed and held for the reset timeout
+ * to hold.
+ */
+ del_timer(&state->keyreset_timer);
+
if (--state->reset_seq_cnt == 0)
state->reset_canceled = false;
} else if (value == 1) {
/* key press, not autorepeat */
if (++state->reset_seq_cnt == state->reset_seq_len &&
- !state->reset_canceled) {
- return true;
+ !state->reset_canceled) {
+ sysrq_handle_reset_request(state);
}
}
-
- return false;
}
static void sysrq_reinject_alt_sysrq(struct work_struct *work)
@@ -746,10 +773,8 @@ static bool sysrq_handle_keypress(struct sysrq_state *sysrq,
if (was_active)
schedule_work(&sysrq->reinject_work);
- if (sysrq_detect_reset_sequence(sysrq, code, value)) {
- /* Force emergency reboot */
- __handle_sysrq(sysrq_xlate[KEY_B], false);
- }
+ /* Check for reset sequence */
+ sysrq_detect_reset_sequence(sysrq, code, value);
} else if (value == 0 && test_and_clear_bit(code, sysrq->key_down)) {
/*
@@ -810,6 +835,7 @@ static int sysrq_connect(struct input_handler *handler,
sysrq->handle.handler = handler;
sysrq->handle.name = "sysrq";
sysrq->handle.private = sysrq;
+ setup_timer(&sysrq->keyreset_timer, sysrq_do_reset, 0);
error = input_register_handle(&sysrq->handle);
if (error) {
@@ -839,6 +865,7 @@ static void sysrq_disconnect(struct input_handle *handle)
input_close_device(handle);
cancel_work_sync(&sysrq->reinject_work);
+ del_timer_sync(&sysrq->keyreset_timer);
input_unregister_handle(handle);
kfree(sysrq);
}
@@ -868,8 +895,6 @@ static struct input_handler sysrq_handler = {
static bool sysrq_handler_registered;
-unsigned short platform_sysrq_reset_seq[] __weak = { KEY_RESERVED };
-
static inline void sysrq_register_handler(void)
{
unsigned short key;
@@ -929,6 +954,8 @@ static struct kernel_param_ops param_ops_sysrq_reset_seq = {
module_param_array_named(reset_seq, sysrq_reset_seq, sysrq_reset_seq,
&sysrq_reset_seq_len, 0644);
+module_param_named(sysrq_downtime_ms, sysrq_reset_downtime_ms, int, 0644);
+
#else
static inline void sysrq_register_handler(void)
--
1.7.9.5
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