diff options
| -rw-r--r-- | Documentation/admin-guide/sysrq.rst | 11 | ||||
| -rw-r--r-- | drivers/tty/sysrq.c | 19 |
2 files changed, 26 insertions, 4 deletions
diff --git a/Documentation/admin-guide/sysrq.rst b/Documentation/admin-guide/sysrq.rst index 51906e47327b..2f2e5bd440f9 100644 --- a/Documentation/admin-guide/sysrq.rst +++ b/Documentation/admin-guide/sysrq.rst @@ -75,10 +75,19 @@ On other submit a patch to be included in this section. On all - Write a character to /proc/sysrq-trigger. e.g.:: + Write a single character to /proc/sysrq-trigger. + Only the first character is processed, the rest of the string is + ignored. However, it is not recommended to write any extra characters + as the behavior is undefined and might change in the future versions. + E.g.:: echo t > /proc/sysrq-trigger + Alternatively, write multiple characters prepended by underscore. + This way, all characters will be processed. E.g.:: + + echo _reisub > /proc/sysrq-trigger + The :kbd:`<command key>` is case sensitive. What are the 'command' keys? diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index 6b4a28bcf2f5..02217e3c916b 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -1150,16 +1150,29 @@ EXPORT_SYMBOL(unregister_sysrq_key); #ifdef CONFIG_PROC_FS /* * writing 'C' to /proc/sysrq-trigger is like sysrq-C + * Normally, only the first character written is processed. + * However, if the first character is an underscore, + * all characters are processed. */ static ssize_t write_sysrq_trigger(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { - if (count) { + bool bulk = false; + size_t i; + + for (i = 0; i < count; i++) { char c; - if (get_user(c, buf)) + 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; |