Merge branch 'rework/nbcon-base' into for-linus

1 files changed, 73 insertions, 49 deletions

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 95689eccf0fb..be95a6851164 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -102,12 +102,6 @@ DEFINE_STATIC_SRCU(console_srcu);
  */
 int __read_mostly suppress_printk;
 
-/*
- * During panic, heavy printk by other CPUs can delay the
- * panic and risk deadlock on console resources.
- */
-static int __read_mostly suppress_panic_printk;
-
 #ifdef CONFIG_LOCKDEP
 static struct lockdep_map console_lock_dep_map = {
 	.name = "console_lock"
@@ -445,6 +439,12 @@ static int console_msg_format = MSG_FORMAT_DEFAULT;
 static DEFINE_MUTEX(syslog_lock);
 
 #ifdef CONFIG_PRINTK
+/*
+ * During panic, heavy printk by other CPUs can delay the
+ * panic and risk deadlock on console resources.
+ */
+static int __read_mostly suppress_panic_printk;
+
 DECLARE_WAIT_QUEUE_HEAD(log_wait);
 /* All 3 protected by @syslog_lock. */
 /* the next printk record to read by syslog(READ) or /proc/kmsg */
@@ -494,7 +494,7 @@ _DEFINE_PRINTKRB(printk_rb_static, CONFIG_LOG_BUF_SHIFT - PRB_AVGBITS,
 
 static struct printk_ringbuffer printk_rb_dynamic;
 
-static struct printk_ringbuffer *prb = &printk_rb_static;
+struct printk_ringbuffer *prb = &printk_rb_static;
 
 /*
  * We cannot access per-CPU data (e.g. per-CPU flush irq_work) before
@@ -698,9 +698,6 @@ out:
 	return len;
 }
 
-static bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
-				    bool is_extended, bool may_supress);
-
 /* /dev/kmsg - userspace message inject/listen interface */
 struct devkmsg_user {
 	atomic64_t seq;
@@ -2348,22 +2345,6 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre
 
 static u64 syslog_seq;
 
-static size_t record_print_text(const struct printk_record *r,
-				bool syslog, bool time)
-{
-	return 0;
-}
-static ssize_t info_print_ext_header(char *buf, size_t size,
-				     struct printk_info *info)
-{
-	return 0;
-}
-static ssize_t msg_print_ext_body(char *buf, size_t size,
-				  char *text, size_t text_len,
-				  struct dev_printk_info *dev_info) { return 0; }
-static void console_lock_spinning_enable(void) { }
-static int console_lock_spinning_disable_and_check(int cookie) { return 0; }
-static bool suppress_message_printing(int level) { return false; }
 static bool pr_flush(int timeout_ms, bool reset_on_progress) { return true; }
 static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress) { return true; }
 
@@ -2717,6 +2698,8 @@ static void __console_unlock(void)
 	up_console_sem();
 }
 
+#ifdef CONFIG_PRINTK
+
 /*
  * Prepend the message in @pmsg->pbufs->outbuf with a "dropped message". This
  * is achieved by shifting the existing message over and inserting the dropped
@@ -2731,8 +2714,7 @@ static void __console_unlock(void)
  *
  * If @pmsg->pbufs->outbuf is modified, @pmsg->outbuf_len is updated.
  */
-#ifdef CONFIG_PRINTK
-static void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped)
+void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped)
 {
 	struct printk_buffers *pbufs = pmsg->pbufs;
 	const size_t scratchbuf_sz = sizeof(pbufs->scratchbuf);
@@ -2763,9 +2745,6 @@ static void console_prepend_dropped(struct printk_message *pmsg, unsigned long d
 	memcpy(outbuf, scratchbuf, len);
 	pmsg->outbuf_len += len;
 }
-#else
-#define console_prepend_dropped(pmsg, dropped)
-#endif /* CONFIG_PRINTK */
 
 /*
  * Read and format the specified record (or a later record if the specified
@@ -2786,8 +2765,8 @@ static void console_prepend_dropped(struct printk_message *pmsg, unsigned long d
  * of @pmsg are valid. (See the documentation of struct printk_message
  * for information about the @pmsg fields.)
  */
-static bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
-				    bool is_extended, bool may_suppress)
+bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
+			     bool is_extended, bool may_suppress)
 {
 	static int panic_console_dropped;
 
@@ -2846,6 +2825,13 @@ out:
 }
 
 /*
+ * Used as the printk buffers for non-panic, serialized console printing.
+ * This is for legacy (!CON_NBCON) as well as all boot (CON_BOOT) consoles.
+ * Its usage requires the console_lock held.
+ */
+struct printk_buffers printk_shared_pbufs;
+
+/*
  * Print one record for the given console. The record printed is whatever
  * record is the next available record for the given console.
  *
@@ -2862,12 +2848,10 @@ out:
  */
 static bool console_emit_next_record(struct console *con, bool *handover, int cookie)
 {
-	static struct printk_buffers pbufs;
-
 	bool is_extended = console_srcu_read_flags(con) & CON_EXTENDED;
-	char *outbuf = &pbufs.outbuf[0];
+	char *outbuf = &printk_shared_pbufs.outbuf[0];
 	struct printk_message pmsg = {
-		.pbufs = &pbufs,
+		.pbufs = &printk_shared_pbufs,
 	};
 	unsigned long flags;
 
@@ -2918,6 +2902,16 @@ skip:
 	return true;
 }
 
+#else
+
+static bool console_emit_next_record(struct console *con, bool *handover, int cookie)
+{
+	*handover = false;
+	return false;
+}
+
+#endif /* CONFIG_PRINTK */
+
 /*
  * Print out all remaining records to all consoles.
  *
@@ -3162,6 +3156,7 @@ void console_flush_on_panic(enum con_flush_mode mode)
 
 	if (mode == CONSOLE_REPLAY_ALL) {
 		struct console *c;
+		short flags;
 		int cookie;
 		u64 seq;
 
@@ -3169,11 +3164,17 @@ void console_flush_on_panic(enum con_flush_mode mode)
 
 		cookie = console_srcu_read_lock();
 		for_each_console_srcu(c) {
-			/*
-			 * This is an unsynchronized assignment, but the
-			 * kernel is in "hope and pray" mode anyway.
-			 */
-			c->seq = seq;
+			flags = console_srcu_read_flags(c);
+
+			if (flags & CON_NBCON) {
+				nbcon_seq_force(c, seq);
+			} else {
+				/*
+				 * This is an unsynchronized assignment. On
+				 * panic legacy consoles are only best effort.
+				 */
+				c->seq = seq;
+			}
 		}
 		console_srcu_read_unlock(cookie);
 	}
@@ -3325,11 +3326,6 @@ static void try_enable_default_console(struct console *newcon)
 		newcon->flags |= CON_CONSDEV;
 }
 
-#define con_printk(lvl, con, fmt, ...)			\
-	printk(lvl pr_fmt("%sconsole [%s%d] " fmt),	\
-	       (con->flags & CON_BOOT) ? "boot" : "",	\
-	       con->name, con->index, ##__VA_ARGS__)
-
 static void console_init_seq(struct console *newcon, bool bootcon_registered)
 {
 	struct console *con;
@@ -3443,6 +3439,15 @@ void register_console(struct console *newcon)
 		goto unlock;
 	}
 
+	if (newcon->flags & CON_NBCON) {
+		/*
+		 * Ensure the nbcon console buffers can be allocated
+		 * before modifying any global data.
+		 */
+		if (!nbcon_alloc(newcon))
+			goto unlock;
+	}
+
 	/*
 	 * See if we want to enable this console driver by default.
 	 *
@@ -3470,8 +3475,11 @@ void register_console(struct console *newcon)
 		err = try_enable_preferred_console(newcon, false);
 
 	/* printk() messages are not printed to the Braille console. */
-	if (err || newcon->flags & CON_BRL)
+	if (err || newcon->flags & CON_BRL) {
+		if (newcon->flags & CON_NBCON)
+			nbcon_free(newcon);
 		goto unlock;
+	}
 
 	/*
 	 * If we have a bootconsole, and are switching to a real console,
@@ -3487,6 +3495,9 @@ void register_console(struct console *newcon)
 	newcon->dropped = 0;
 	console_init_seq(newcon, bootcon_registered);
 
+	if (newcon->flags & CON_NBCON)
+		nbcon_init(newcon);
+
 	/*
 	 * Put this console in the list - keep the
 	 * preferred driver at the head of the list.
@@ -3578,6 +3589,9 @@ static int unregister_console_locked(struct console *console)
 	 */
 	synchronize_srcu(&console_srcu);
 
+	if (console->flags & CON_NBCON)
+		nbcon_free(console);
+
 	console_sysfs_notify();
 
 	if (console->exit)
@@ -3732,6 +3746,7 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre
 	struct console *c;
 	u64 last_diff = 0;
 	u64 printk_seq;
+	short flags;
 	int cookie;
 	u64 diff;
 	u64 seq;
@@ -3762,6 +3777,9 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre
 		for_each_console_srcu(c) {
 			if (con && con != c)
 				continue;
+
+			flags = console_srcu_read_flags(c);
+
 			/*
 			 * If consoles are not usable, it cannot be expected
 			 * that they make forward progress, so only increment
@@ -3769,7 +3787,13 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre
 			 */
 			if (!console_is_usable(c))
 				continue;
-			printk_seq = c->seq;
+
+			if (flags & CON_NBCON) {
+				printk_seq = nbcon_seq_read(c);
+			} else {
+				printk_seq = c->seq;
+			}
+
 			if (printk_seq < seq)
 				diff += seq - printk_seq;
 		}