Commit 38335cc5 authored by Petr Mladek's avatar Petr Mladek
Browse files

Merge branch 'rework/kthreads' into for-linus

parents 12831f64 b87f0230

include/linux/printk.h

+5 −0
Original line number Diff line number Diff line
@@ -173,6 +173,7 @@ 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
@@ -237,6 +238,10 @@ 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/panic.c

+2 −0
Original line number Diff line number Diff line
@@ -297,6 +297,7 @@ 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 {

		/*
@@ -304,6 +305,7 @@ void panic(const char *fmt, ...) 
		 * kmsg_dump, we will need architecture dependent extra

		 * works in addition to stopping other CPUs.

		 */

		try_block_console_kthreads(10000);

		crash_smp_send_stop();

	}

kernel/printk/internal.h

+2 −0
Original line number Diff line number Diff line
@@ -20,6 +20,8 @@ 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,

kernel/printk/printk.c

+7 −1
Original line number Diff line number Diff line
@@ -250,6 +250,9 @@ static atomic_t console_kthreads_active = ATOMIC_INIT(0); 
#define console_kthread_printing_exit() \

	atomic_dec(&console_kthreads_active)



/* Block console kthreads to avoid processing new messages. */

bool block_console_kthreads;



/*

 * Helper macros to handle lockdep when locking/unlocking console_sem. We use

 * macros instead of functions so that _RET_IP_ contains useful information.
@@ -3729,7 +3732,10 @@ static bool printer_should_wake(struct console *con, u64 seq) 
		return true;



	if (con->blocked ||

	    console_kthreads_atomically_blocked()) {

	    console_kthreads_atomically_blocked() ||

	    block_console_kthreads ||

	    system_state > SYSTEM_RUNNING ||

	    oops_in_progress) {

		return false;

	}

kernel/printk/printk_safe.c

+32 −0
Original line number Diff line number Diff line
@@ -8,7 +8,9 @@ 
#include <linux/smp.h>

#include <linux/cpumask.h>

#include <linux/printk.h>

#include <linux/console.h>

#include <linux/kprobes.h>

#include <linux/delay.h>



#include "internal.h"
@@ -50,3 +52,33 @@ asmlinkage int vprintk(const char *fmt, va_list args) 
	return vprintk_default(fmt, args);

}

EXPORT_SYMBOL(vprintk);



/**

 * try_block_console_kthreads() - Try to block console kthreads and

 *	make the global console_lock() avaialble

 *

 * @timeout_ms:        The maximum time (in ms) to wait.

 *

 * Prevent console kthreads from starting processing new messages. Wait

 * until the global console_lock() become available.

 *

 * Context: Can be called in any context.

 */

void try_block_console_kthreads(int timeout_ms)

{

	block_console_kthreads = true;



	/* Do not wait when the console lock could not be safely taken. */

	if (this_cpu_read(printk_context) || in_nmi())

		return;



	while (timeout_ms > 0) {

		if (console_trylock()) {

			console_unlock();

			return;

		}



		udelay(1000);

		timeout_ms -= 1;

	}

}