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>
---
Changes for v3:
- Cancel timer if any of the key in the combo is released before
the timeout period expires.
drivers/tty/sysrq.c | 44 +++++++++++++++++++++++++++++++++-----------
1 file changed, 33 insertions(+), 11 deletions(-)
diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c
index 7953dfa..2255965 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_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_timeout;
};
#define SYSRQ_KEY_RESET_MAX 20 /* Should be plenty */
@@ -617,7 +622,14 @@ 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_handle_reset_request(struct sysrq_state *state)
+{
+ unsigned long expires = jiffies + msecs_to_jiffies(sysrq_downtime_ms);
+ state->keyreset_timeout.expires = expires;
+ add_timer(&state->keyreset_timeout);
+}
+
+static void sysrq_detect_reset_sequence(struct sysrq_state *state,
unsigned int code, int value)
{
if (!test_bit(code, state->reset_keybit)) {
@@ -628,18 +640,27 @@ static bool sysrq_detect_reset_sequence(struct sysrq_state *state,
if (value && state->reset_seq_cnt)
state->reset_canceled = true;
} 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_timeout);
+
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_handle_reset_timeout(unsigned long data)
+{
+ __handle_sysrq(sysrq_xlate[KEY_B], false);
}
static void sysrq_reinject_alt_sysrq(struct work_struct *work)
@@ -746,10 +767,8 @@ 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 +829,8 @@ static int sysrq_connect(struct input_handler *handler,
sysrq->handle.handler = handler;
sysrq->handle.name = "sysrq";
sysrq->handle.private = sysrq;
+ init_timer(&sysrq->keyreset_timeout);
+ sysrq->keyreset_timeout.function = sysrq_handle_reset_timeout;
error = input_register_handle(&sysrq->handle);
if (error) {
@@ -839,6 +860,7 @@ static void sysrq_disconnect(struct input_handle *handle)
input_close_device(handle);
cancel_work_sync(&sysrq->reinject_work);
+ del_timer(&sysrq->keyreset_timeout);
input_unregister_handle(handle);
kfree(sysrq);
}
@@ -868,8 +890,6 @@ 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 +949,8 @@ 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(sysrq_downtime_ms, int, 0644);
+
#else
static inline void sysrq_register_handler(void)
--
1.7.9.5
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