diff options
| -rw-r--r-- | include/linux/console.h | 1 | ||||
| -rw-r--r-- | kernel/printk.c | 50 |
2 files changed, 34 insertions, 17 deletions
diff --git a/include/linux/console.h b/include/linux/console.h index 08734e660d4..d0f8a800949 100644 --- a/include/linux/console.h +++ b/include/linux/console.h @@ -87,6 +87,7 @@ void give_up_console(const struct consw *sw); #define CON_CONSDEV (2) /* Last on the command line */ #define CON_ENABLED (4) #define CON_BOOT (8) +#define CON_ANYTIME (16) /* Safe to call when cpu is offline */ struct console { diff --git a/kernel/printk.c b/kernel/printk.c index 19a95561929..6b89dd9d11b 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -327,7 +327,9 @@ static void __call_console_drivers(unsigned long start, unsigned long end) struct console *con; for (con = console_drivers; con; con = con->next) { - if ((con->flags & CON_ENABLED) && con->write) + if ((con->flags & CON_ENABLED) && con->write && + (cpu_online(smp_processor_id()) || + (con->flags & CON_ANYTIME))) con->write(con, &LOG_BUF(start), end - start); } } @@ -453,6 +455,18 @@ __attribute__((weak)) unsigned long long printk_clock(void) return sched_clock(); } +/* Check if we have any console registered that can be called early in boot. */ +static int have_callable_console(void) +{ + struct console *con; + + for (con = console_drivers; con; con = con->next) + if (con->flags & CON_ANYTIME) + return 1; + + return 0; +} + /** * printk - print a kernel message * @fmt: format string @@ -566,27 +580,29 @@ asmlinkage int vprintk(const char *fmt, va_list args) log_level_unknown = 1; } - if (!cpu_online(smp_processor_id())) { + if (!down_trylock(&console_sem)) { /* - * Some console drivers may assume that per-cpu resources have - * been allocated. So don't allow them to be called by this - * CPU until it is officially up. We shouldn't be calling into - * random console drivers on a CPU which doesn't exist yet.. + * We own the drivers. We can drop the spinlock and + * let release_console_sem() print the text, maybe ... */ + console_locked = 1; printk_cpu = UINT_MAX; spin_unlock_irqrestore(&logbuf_lock, flags); - goto out; - } - if (!down_trylock(&console_sem)) { - console_locked = 1; + /* - * We own the drivers. We can drop the spinlock and let - * release_console_sem() print the text + * Console drivers may assume that per-cpu resources have + * been allocated. So unless they're explicitly marked as + * being able to cope (CON_ANYTIME) don't call them until + * this CPU is officially up. */ - printk_cpu = UINT_MAX; - spin_unlock_irqrestore(&logbuf_lock, flags); - console_may_schedule = 0; - release_console_sem(); + if (cpu_online(smp_processor_id()) || have_callable_console()) { + console_may_schedule = 0; + release_console_sem(); + } else { + /* Release by hand to avoid flushing the buffer. */ + console_locked = 0; + up(&console_sem); + } } else { /* * Someone else owns the drivers. We drop the spinlock, which @@ -596,7 +612,7 @@ asmlinkage int vprintk(const char *fmt, va_list args) printk_cpu = UINT_MAX; spin_unlock_irqrestore(&logbuf_lock, flags); } -out: + preempt_enable(); return printed_len; } |