Merge branch 'for-6.13-force-console' into for-linus

Author: pmladek

drivers/tty/sysrq.c

@@ -582,7 +582,6 @@ static void __sysrq_put_key_op(u8 key, const struct sysrq_key_op *op_p)
 void __handle_sysrq(u8 key, bool check_mask)
 {
 	const struct sysrq_key_op *op_p;
-	int orig_log_level;
 	int orig_suppress_printk;
 	int i;
 
@@ -592,13 +591,12 @@ void __handle_sysrq(u8 key, bool check_mask)
 	rcu_sysrq_start();
 	rcu_read_lock();
 	/*
-	 * Raise the apparent loglevel to maximum so that the sysrq header
-	 * is shown to provide the user with positive feedback.  We do not
-	 * simply emit this at KERN_EMERG as that would change message
-	 * routing in the consumers of /proc/kmsg.
+	 * Enter in the force_console context so that sysrq header is shown to
+	 * provide the user with positive feedback.  We do not simply emit this
+	 * at KERN_EMERG as that would change message routing in the consumers
+	 * of /proc/kmsg.
 	 */
-	orig_log_level = console_loglevel;
-	console_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
+	printk_force_console_enter();
 
 	op_p = __sysrq_get_key_op(key);
 	if (op_p) {
@@ -608,11 +606,11 @@ void __handle_sysrq(u8 key, bool check_mask)
 		 */
 		if (!check_mask || sysrq_on_mask(op_p->enable_mask)) {
 			pr_info("%s\n", op_p->action_msg);
-			console_loglevel = orig_log_level;
+			printk_force_console_exit();
 			op_p->handler(key);
 		} else {
 			pr_info("This sysrq operation is disabled.\n");
-			console_loglevel = orig_log_level;
+			printk_force_console_exit();
 		}
 	} else {
 		pr_info("HELP : ");
@@ -630,7 +628,7 @@ void __handle_sysrq(u8 key, bool check_mask)
 			}
 		}
 		pr_cont("\n");
-		console_loglevel = orig_log_level;
+		printk_force_console_exit();
 	}
 	rcu_read_unlock();
 	rcu_sysrq_end();

include/linux/printk.h

@@ -166,6 +166,9 @@ __printf(1, 2) __cold int _printk_deferred(const char *fmt, ...);
 extern void __printk_deferred_enter(void);
 extern void __printk_deferred_exit(void);
 
+extern void printk_force_console_enter(void);
+extern void printk_force_console_exit(void);
+
 /*
  * The printk_deferred_enter/exit macros are available only as a hack for
  * some code paths that need to defer all printk console printing. Interrupts
@@ -229,6 +232,14 @@ static inline void printk_deferred_exit(void)
 {
 }
 
+static inline void printk_force_console_enter(void)
+{
+}
+
+static inline void printk_force_console_exit(void)
+{
+}
+
 static inline int printk_ratelimit(void)
 {
 	return 0;

kernel/printk/internal.h

@@ -53,6 +53,8 @@ int devkmsg_sysctl_set_loglvl(const struct ctl_table *table, int write,
 
 /* Flags for a single printk record. */
 enum printk_info_flags {
+	/* always show on console, ignore console_loglevel */
+	LOG_FORCE_CON	= 1,
 	LOG_NEWLINE	= 2,	/* text ended with a newline */
 	LOG_CONT	= 8,	/* text is a fragment of a continuation line */
 };
@@ -90,6 +92,7 @@ bool printk_percpu_data_ready(void);
 
 void defer_console_output(void);
 bool is_printk_legacy_deferred(void);
+bool is_printk_force_console(void);
 
 u16 printk_parse_prefix(const char *text, int *level,
 			enum printk_info_flags *flags);

kernel/printk/printk.c

@@ -1337,11 +1337,11 @@ static void boot_delay_msec(int level)
 {
 	unsigned long long k;
 	unsigned long timeout;
+	bool suppress = !is_printk_force_console() &&
+			suppress_message_printing(level);
 
-	if ((boot_delay == 0 || system_state >= SYSTEM_RUNNING)
-		|| suppress_message_printing(level)) {
+	if ((boot_delay == 0 || system_state >= SYSTEM_RUNNING) || suppress)
 		return;
-	}
 
 	k = (unsigned long long)loops_per_msec * boot_delay;
 
@@ -2291,13 +2291,19 @@ int vprintk_store(int facility, int level,
 	if (dev_info)
 		flags |= LOG_NEWLINE;
 
+	if (is_printk_force_console())
+		flags |= LOG_FORCE_CON;
+
 	if (flags & LOG_CONT) {
 		prb_rec_init_wr(&r, reserve_size);
 		if (prb_reserve_in_last(&e, prb, &r, caller_id, PRINTKRB_RECORD_MAX)) {
 			text_len = printk_sprint(&r.text_buf[r.info->text_len], reserve_size,
 						 facility, &flags, fmt, args);
 			r.info->text_len += text_len;
 
+			if (flags & LOG_FORCE_CON)
+				r.info->flags |= LOG_FORCE_CON;
+
 			if (flags & LOG_NEWLINE) {
 				r.info->flags |= LOG_NEWLINE;
 				prb_final_commit(&e);
@@ -2965,6 +2971,7 @@ bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
 	struct printk_info info;
 	struct printk_record r;
 	size_t len = 0;
+	bool force_con;
 
 	/*
 	 * Formatting extended messages requires a separate buffer, so use the
@@ -2983,9 +2990,13 @@ bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
 
 	pmsg->seq = r.info->seq;
 	pmsg->dropped = r.info->seq - seq;
+	force_con = r.info->flags & LOG_FORCE_CON;
 
-	/* Skip record that has level above the console loglevel. */
-	if (may_suppress && suppress_message_printing(r.info->level))
+	/*
+	 * Skip records that are not forced to be printed on consoles and that
+	 * has level above the console loglevel.
+	 */
+	if (!force_con && may_suppress && suppress_message_printing(r.info->level))
 		goto out;
 
 	if (is_extended) {

kernel/printk/printk_safe.c

@@ -12,6 +12,24 @@
 
 #include "internal.h"
 
+/* Context where printk messages are never suppressed */
+static atomic_t force_con;
+
+void printk_force_console_enter(void)
+{
+	atomic_inc(&force_con);
+}
+
+void printk_force_console_exit(void)
+{
+	atomic_dec(&force_con);
+}
+
+bool is_printk_force_console(void)
+{
+	return atomic_read(&force_con);
+}
+
 static DEFINE_PER_CPU(int, printk_context);
 
 /* Can be preempted by NMI. */