Commit 4859bcd7 authored by Petr Mladek's avatar Petr Mladek
Browse files

Merge branch 'for-6.14-cpu_sync-fixup' into for-linus

parents 3d6f83df 0161e2d6

kernel/printk/internal.h

+6 −0
Original line number Diff line number Diff line
@@ -338,3 +338,9 @@ bool printk_get_next_message(struct printk_message *pmsg, u64 seq, 
void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped);

void console_prepend_replay(struct printk_message *pmsg);

#endif



#ifdef CONFIG_SMP

bool is_printk_cpu_sync_owner(void);

#else

static inline bool is_printk_cpu_sync_owner(void) { return false; }

#endif

kernel/printk/printk.c

+5 −0
Original line number Diff line number Diff line
@@ -4922,6 +4922,11 @@ void console_try_replay_all(void) 
static atomic_t printk_cpu_sync_owner = ATOMIC_INIT(-1);

static atomic_t printk_cpu_sync_nested = ATOMIC_INIT(0);



bool is_printk_cpu_sync_owner(void)

{

	return (atomic_read(&printk_cpu_sync_owner) == raw_smp_processor_id());

}



/**

 * __printk_cpu_sync_wait() - Busy wait until the printk cpu-reentrant

 *                            spinning lock is not owned by any CPU.

kernel/printk/printk_safe.c

+6 −10
Original line number Diff line number Diff line
@@ -61,10 +61,15 @@ bool is_printk_legacy_deferred(void) 
	/*

	 * The per-CPU variable @printk_context can be read safely in any

	 * context. CPU migration is always disabled when set.

	 *

	 * A context holding the printk_cpu_sync must not spin waiting for

	 * another CPU. For legacy printing, it could be the console_lock

	 * or the port lock.

	 */

	return (force_legacy_kthread() ||

		this_cpu_read(printk_context) ||

		in_nmi());

		in_nmi() ||

		is_printk_cpu_sync_owner());

}



asmlinkage int vprintk(const char *fmt, va_list args)
@@ -74,15 +79,6 @@ asmlinkage int vprintk(const char *fmt, va_list args) 
	if (unlikely(kdb_trap_printk && kdb_printf_cpu < 0))

		return vkdb_printf(KDB_MSGSRC_PRINTK, fmt, args);

#endif



	/*

	 * Use the main logbuf even in NMI. But avoid calling console

	 * drivers that might have their own locks.

	 */

	if (is_printk_legacy_deferred())

		return vprintk_deferred(fmt, args);



	/* No obstacles. */

	return vprintk_default(fmt, args);

}

EXPORT_SYMBOL(vprintk);