diff options
Diffstat (limited to 'kernel/printk')
| -rw-r--r-- | kernel/printk/printk.c | 97 |
1 files changed, 42 insertions, 55 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index c963ba534a78..2523332bd998 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -1483,58 +1483,6 @@ static void zap_locks(void) sema_init(&console_sem, 1); } -/* - * Check if we have any console that is capable of printing while cpu is - * booting or shutting down. Requires console_sem. - */ -static int have_callable_console(void) -{ - struct console *con; - - for_each_console(con) - if (con->flags & CON_ANYTIME) - return 1; - - return 0; -} - -/* - * Can we actually use the console at this time on this cpu? - * - * 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. - */ -static inline int can_use_console(unsigned int cpu) -{ - return cpu_online(cpu) || have_callable_console(); -} - -/* - * Try to get console ownership to actually show the kernel - * messages from a 'printk'. Return true (and with the - * console_lock held, and 'console_locked' set) if it - * is successful, false otherwise. - */ -static int console_trylock_for_printk(void) -{ - unsigned int cpu = smp_processor_id(); - - if (!console_trylock()) - return 0; - /* - * If we can't use the console, we need to release the console - * semaphore by hand to avoid flushing the buffer. We need to hold the - * console semaphore in order to do this test safely. - */ - if (!can_use_console(cpu)) { - console_locked = 0; - up_console_sem(); - return 0; - } - return 1; -} - int printk_delay_msec __read_mostly; static inline void printk_delay(void) @@ -1681,7 +1629,6 @@ asmlinkage int vprintk_emit(int facility, int level, boot_delay_msec(level); printk_delay(); - /* This stops the holder of console_sem just where we want him */ local_irq_save(flags); this_cpu = smp_processor_id(); @@ -1705,6 +1652,7 @@ asmlinkage int vprintk_emit(int facility, int level, } lockdep_off(); + /* This stops the holder of console_sem just where we want him */ raw_spin_lock(&logbuf_lock); logbuf_cpu = this_cpu; @@ -1821,7 +1769,7 @@ asmlinkage int vprintk_emit(int facility, int level, * semaphore. The release will print out buffers and wake up * /dev/kmsg and syslog() users. */ - if (console_trylock_for_printk()) + if (console_trylock()) console_unlock(); preempt_enable(); lockdep_on(); @@ -2184,6 +2132,33 @@ int is_console_locked(void) return console_locked; } +/* + * Check if we have any console that is capable of printing while cpu is + * booting or shutting down. Requires console_sem. + */ +static int have_callable_console(void) +{ + struct console *con; + + for_each_console(con) + if (con->flags & CON_ANYTIME) + return 1; + + return 0; +} + +/* + * Can we actually use the console at this time on this cpu? + * + * 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. + */ +static inline int can_use_console(void) +{ + return cpu_online(raw_smp_processor_id()) || have_callable_console(); +} + static void console_cont_flush(char *text, size_t size) { unsigned long flags; @@ -2254,9 +2229,21 @@ void console_unlock(void) do_cond_resched = console_may_schedule; console_may_schedule = 0; +again: + /* + * We released the console_sem lock, so we need to recheck if + * cpu is online and (if not) is there at least one CON_ANYTIME + * console. + */ + if (!can_use_console()) { + console_locked = 0; + up_console_sem(); + return; + } + /* flush buffered message fragment immediately to console */ console_cont_flush(text, sizeof(text)); -again: + for (;;) { struct printk_log *msg; size_t ext_len = 0; |