[PATCH v3 4/5] panic: add 'panic_sys_info=' setup option for kernel cmdline

[Feng Tang <feng.tang@linux.alibaba.com>]

'panic_sys_info=' sysctl interface is already added for runtime setting.
Add counterpart kernel cmdline option for boottime setting.

Suggested-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
---
 Documentation/admin-guide/kernel-parameters.txt | 15 +++++++++++++++
 kernel/panic.c                                  |  9 +++++++++
 2 files changed, 24 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index abb2ade021ee..39ddef7c5857 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4541,6 +4541,21 @@
 			Use this option carefully, maybe worth to setup a
 			bigger log buffer with "log_buf_len" along with this.
 
+	panic_sys_info= A comma separated list of extra information to be dumped
+                        on panic.
+                        Format: val[,val...]
+                        Where @val can be any of the following:
+
+                        tasks:          print all tasks info
+                        mem:            print system memory info
+			timers:         print timers info
+                        locks:          print locks info if CONFIG_LOCKDEP is on
+                        ftrace:         print ftrace buffer
+                        all_bt:         print all CPUs backtrace (if available in the arch)
+                        blocked_tasks:  print only tasks in uninterruptible (blocked) state
+
+                        This is a human readable alternative to the 'panic_print' option.
+
 	parkbd.port=	[HW] Parallel port number the keyboard adapter is
 			connected to, default is 0.
 			Format: <parport#>
diff --git a/kernel/panic.c b/kernel/panic.c
index d7aa427dc23c..d9d4fcd5e318 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -143,6 +143,15 @@ static __init int kernel_panic_sysctls_init(void)
 late_initcall(kernel_panic_sysctls_init);
 #endif
 
+/* The format is "panic_sys_info=tasks,mem,locks,ftrace,..." */
+static int __init setup_panic_sys_info(char *buf)
+{
+	/* There is no risk of race in kernel boot phase */
+	panic_print = sys_info_parse_param(buf);
+	return 1;
+}
+__setup("panic_sys_info=", setup_panic_sys_info);
+
 static atomic_t warn_count = ATOMIC_INIT(0);
 
 #ifdef CONFIG_SYSFS
-- 
2.43.5