Commit 93d102f0 authored by John Ogness's avatar John Ogness Committed by Petr Mladek
Browse files

printk: remove safe buffers 



With @logbuf_lock removed, the high level printk functions for
storing messages are lockless. Messages can be stored from any
context, so there is no need for the NMI and safe buffers anymore.
Remove the NMI and safe buffers.

Although the safe buffers are removed, the NMI and safe context
tracking is still in place. In these contexts, store the message
immediately but still use irq_work to defer the console printing.

Since printk recursion tracking is in place, safe context tracking
for most of printk is not needed. Remove it. Only safe context
tracking relating to the console and console_owner locks is left
in place. This is because the console and console_owner locks are
needed for the actual printing.

Signed-off-by: default avatarJohn Ogness <john.ogness@linutronix.de>
Reviewed-by: default avatarPetr Mladek <pmladek@suse.com>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210715193359.25946-4-john.ogness@linutronix.de
parent 002eb6ad

arch/powerpc/kernel/traps.c

+0 −1
Original line number Diff line number Diff line
@@ -170,7 +170,6 @@ extern void panic_flush_kmsg_start(void) 


extern void panic_flush_kmsg_end(void)

{

	printk_safe_flush_on_panic();

	kmsg_dump(KMSG_DUMP_PANIC);

	bust_spinlocks(0);

	debug_locks_off();

arch/powerpc/kernel/watchdog.c

+0 −5
Original line number Diff line number Diff line
@@ -183,11 +183,6 @@ static void watchdog_smp_panic(int cpu, u64 tb) 


	wd_smp_unlock(&flags);



	printk_safe_flush();

	/*

	 * printk_safe_flush() seems to require another print

	 * before anything actually goes out to console.

	 */

	if (sysctl_hardlockup_all_cpu_backtrace)

		trigger_allbutself_cpu_backtrace();

include/linux/printk.h

+0 −10
Original line number Diff line number Diff line
@@ -208,8 +208,6 @@ void dump_stack_print_info(const char *log_lvl); 
void show_regs_print_info(const char *log_lvl);

extern asmlinkage void dump_stack_lvl(const char *log_lvl) __cold;

extern asmlinkage void dump_stack(void) __cold;

extern void printk_safe_flush(void);

extern void printk_safe_flush_on_panic(void);

#else

static inline __printf(1, 0)

int vprintk(const char *s, va_list args)
@@ -277,14 +275,6 @@ static inline void dump_stack_lvl(const char *log_lvl) 
static inline void dump_stack(void)

{

}



static inline void printk_safe_flush(void)

{

}



static inline void printk_safe_flush_on_panic(void)

{

}

#endif



#ifdef CONFIG_SMP

kernel/kexec_core.c

+0 −1
Original line number Diff line number Diff line
@@ -978,7 +978,6 @@ void crash_kexec(struct pt_regs *regs) 
	old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);

	if (old_cpu == PANIC_CPU_INVALID) {

		/* This is the 1st CPU which comes here, so go ahead. */

		printk_safe_flush_on_panic();

		__crash_kexec(regs);



		/*

kernel/panic.c

+0 −3
Original line number Diff line number Diff line
@@ -247,7 +247,6 @@ void panic(const char *fmt, ...) 
	 * Bypass the panic_cpu check and call __crash_kexec directly.

	 */

	if (!_crash_kexec_post_notifiers) {

		printk_safe_flush_on_panic();

		__crash_kexec(NULL);



		/*
@@ -271,8 +270,6 @@ void panic(const char *fmt, ...) 
	 */

	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);



	/* Call flush even twice. It tries harder with a single online CPU */

	printk_safe_flush_on_panic();

	kmsg_dump(KMSG_DUMP_PANIC);



	/*