Merge branch 'rework/kthreads' into for-linus

Author: pmladek

drivers/tty/sysrq.c

@@ -581,7 +581,6 @@ void __handle_sysrq(int key, bool check_mask)
 
 	rcu_sysrq_start();
 	rcu_read_lock();
-	printk_prefer_direct_enter();
 	/*
 	 * Raise the apparent loglevel to maximum so that the sysrq header
 	 * is shown to provide the user with positive feedback.  We do not
@@ -623,7 +622,6 @@ void __handle_sysrq(int key, bool check_mask)
 		pr_cont("\n");
 		console_loglevel = orig_log_level;
 	}
-	printk_prefer_direct_exit();
 	rcu_read_unlock();
 	rcu_sysrq_end();
 

include/linux/console.h

@@ -16,7 +16,6 @@
 
 #include <linux/atomic.h>
 #include <linux/types.h>
-#include <linux/mutex.h>
 
 struct vc_data;
 struct console_font_op;
@@ -154,22 +153,6 @@ struct console {
 	uint	ospeed;
 	u64	seq;
 	unsigned long dropped;
-	struct task_struct *thread;
-	bool	blocked;
-
-	/*
-	 * The per-console lock is used by printing kthreads to synchronize
-	 * this console with callers of console_lock(). This is necessary in
-	 * order to allow printing kthreads to run in parallel to each other,
-	 * while each safely accessing the @blocked field and synchronizing
-	 * against direct printing via console_lock/console_unlock.
-	 *
-	 * Note: For synchronizing against direct printing via
-	 *       console_trylock/console_unlock, see the static global
-	 *       variable @console_kthreads_active.
-	 */
-	struct mutex lock;
-
 	void	*data;
 	struct	 console *next;
 };

include/linux/printk.h

@@ -169,11 +169,7 @@ extern void __printk_safe_exit(void);
 #define printk_deferred_enter __printk_safe_enter
 #define printk_deferred_exit __printk_safe_exit
 
-extern void printk_prefer_direct_enter(void);
-extern void printk_prefer_direct_exit(void);
-
 extern bool pr_flush(int timeout_ms, bool reset_on_progress);
-extern void try_block_console_kthreads(int timeout_ms);
 
 /*
  * Please don't use printk_ratelimit(), because it shares ratelimiting state
@@ -225,23 +221,11 @@ static inline void printk_deferred_exit(void)
 {
 }
 
-static inline void printk_prefer_direct_enter(void)
-{
-}
-
-static inline void printk_prefer_direct_exit(void)
-{
-}
-
 static inline bool pr_flush(int timeout_ms, bool reset_on_progress)
 {
 	return true;
 }
 
-static inline void try_block_console_kthreads(int timeout_ms)
-{
-}
-
 static inline int printk_ratelimit(void)
 {
 	return 0;

kernel/hung_task.c

@@ -127,8 +127,6 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
 	 * complain:
 	 */
 	if (sysctl_hung_task_warnings) {
-		printk_prefer_direct_enter();
-
 		if (sysctl_hung_task_warnings > 0)
 			sysctl_hung_task_warnings--;
 		pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
@@ -144,8 +142,6 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
 
 		if (sysctl_hung_task_all_cpu_backtrace)
 			hung_task_show_all_bt = true;
-
-		printk_prefer_direct_exit();
 	}
 
 	touch_nmi_watchdog();
@@ -208,17 +204,12 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
 	}
  unlock:
 	rcu_read_unlock();
-	if (hung_task_show_lock) {
-		printk_prefer_direct_enter();
+	if (hung_task_show_lock)
 		debug_show_all_locks();
-		printk_prefer_direct_exit();
-	}
 
 	if (hung_task_show_all_bt) {
 		hung_task_show_all_bt = false;
-		printk_prefer_direct_enter();
 		trigger_all_cpu_backtrace();
-		printk_prefer_direct_exit();
 	}
 
 	if (hung_task_call_panic)

kernel/panic.c

@@ -297,15 +297,13 @@ void panic(const char *fmt, ...)
 		 * unfortunately means it may not be hardened to work in a
 		 * panic situation.
 		 */
-		try_block_console_kthreads(10000);
 		smp_send_stop();
 	} else {
 		/*
 		 * If we want to do crash dump after notifier calls and
 		 * kmsg_dump, we will need architecture dependent extra
 		 * works in addition to stopping other CPUs.
 		 */
-		try_block_console_kthreads(10000);
 		crash_smp_send_stop();
 	}
 
@@ -605,8 +603,6 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
 {
 	disable_trace_on_warning();
 
-	printk_prefer_direct_enter();
-
 	if (file)
 		pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n",
 			raw_smp_processor_id(), current->pid, file, line,
@@ -636,8 +632,6 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
 
 	/* Just a warning, don't kill lockdep. */
 	add_taint(taint, LOCKDEP_STILL_OK);
-
-	printk_prefer_direct_exit();
 }
 
 #ifndef __WARN_FLAGS

kernel/printk/internal.h

@@ -20,8 +20,6 @@ enum printk_info_flags {
 	LOG_CONT	= 8,	/* text is a fragment of a continuation line */
 };
 
-extern bool block_console_kthreads;
-
 __printf(4, 0)
 int vprintk_store(int facility, int level,
 		  const struct dev_printk_info *dev_info,