panic: add note that 'panic_print' parameter is deprecated

Just like for 'panic_print's systcl interface, add similar note for setup
of kernel cmdline parameter and parameter under /sys/module/kernel/.

Also add __core_param_cb() macro, which enables to add special get/set
operation for a kernel parameter.

Link: https://lkml.kernel.org/r/20250825025701.81921-4-feng.tang@linux.alibaba.com
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Askar Safin <safinaskar@zohomail.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
index 3a25122d83e2802e6e6a1475a52816251498b26a..6907aedc4f7484277127ba1b2539e99ffd12aacd 100644 (file)
--- a/include/linux/moduleparam.h
+++ b/include/linux/moduleparam.h
@@ -349,6 +349,19 @@ static inline void kernel_param_unlock(struct module *mod)
        __module_param_call("", name, &param_ops_##type, &var, perm,    \
                            -1, KERNEL_PARAM_FL_UNSAFE)
 
+/**
+ * __core_param_cb - similar like core_param, with a set/get ops instead of type.
+ * @name: the name of the cmdline and sysfs parameter (often the same as var)
+ * @var: the variable
+ * @ops: the set & get operations for this parameter.
+ * @perm: visibility in sysfs
+ *
+ * Ideally this should be called 'core_param_cb', but the name has been
+ * used for module core parameter, so add the '__' prefix
+ */
+#define __core_param_cb(name, ops, arg, perm) \
+       __module_param_call("", name, ops, arg, perm, -1, 0)
+
 #endif /* !MODULE */
 
 /**

diff --git a/kernel/panic.c b/kernel/panic.c
index 72fcbb5a071badba7769087f56d906ad90fbd6c3..12a10e17ab4ab2b222d9bc37136f70f3799826d2 100644 (file)
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -937,12 +937,29 @@ EXPORT_SYMBOL(__stack_chk_fail);
 #endif
 
 core_param(panic, panic_timeout, int, 0644);
-core_param(panic_print, panic_print, ulong, 0644);
 core_param(pause_on_oops, pause_on_oops, int, 0644);
 core_param(panic_on_warn, panic_on_warn, int, 0644);
 core_param(crash_kexec_post_notifiers, crash_kexec_post_notifiers, bool, 0644);
 core_param(panic_console_replay, panic_console_replay, bool, 0644);
 
+static int panic_print_set(const char *val, const struct kernel_param *kp)
+{
+       pr_info_once("Kernel: 'panic_print' parameter will be obsoleted by both 'panic_sys_info' and 'panic_console_replay'\n");
+       return  param_set_ulong(val, kp);
+}
+
+static int panic_print_get(char *val, const struct kernel_param *kp)
+{
+       pr_info_once("Kernel: 'panic_print' parameter will be obsoleted by both 'panic_sys_info' and 'panic_console_replay'\n");
+       return  param_get_ulong(val, kp);
+}
+
+static const struct kernel_param_ops panic_print_ops = {
+       .set    = panic_print_set,
+       .get    = panic_print_get,
+};
+__core_param_cb(panic_print, &panic_print_ops, &panic_print, 0644);
+
 static int __init oops_setup(char *s)
 {
        if (!s)