@@ -79,6 +79,10 @@ On all
echo t > /proc/sysrq-trigger
+ Alternatively write key combo prepended by underscore. e.g.::
+
+ echo _reisub > /proc/sysrq-trigger
+
The :kbd:`<command key>` is case sensitive.
What are the 'command' keys?
@@ -1150,16 +1150,27 @@ EXPORT_SYMBOL(unregister_sysrq_key);
#ifdef CONFIG_PROC_FS
/*
* writing 'C' to /proc/sysrq-trigger is like sysrq-C
+ * If first character in write is underscore, all characters are interpreted.
*/
static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
- if (count) {
- char c;
+ char bulk = false;
+ size_t i;
- if (get_user(c, buf))
+ for (i = 0; i < count; i++) {
+ bool c;
+
+ if (get_user(c, buf + i))
return -EFAULT;
- __handle_sysrq(c, false);
+
+ if (c == '_')
+ bulk = true;
+ else
+ __handle_sysrq(c, false);
+
+ if (!bulk)
+ break;
}
return count;
Just for convenience. This way we can do: `echo _reisub > /proc/sysrq-trigger` Instead of: `for i in r e i s u b; do echo "$i" > /proc/sysrq-trigger; done;` This can be very useful when trying to execute sysrq combo remotely or from userspace. When sending keys in multiple separate writes, userspace can be killed before whole combo is completed. Therefore putting all keys in single write is more robust approach. Signed-off-by: Tomas Mudrunka <tomas.mudrunka@gmail.com> --- Documentation/admin-guide/sysrq.rst | 4 ++++ drivers/tty/sysrq.c | 19 +++++++++++++++---- 2 files changed, 19 insertions(+), 4 deletions(-)