X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=kernel%2Fprintk.c;h=95b7fe17f124c259a54d0227ac1d0a08ddb62800;hb=25581ad107be24b89d805da51a03d616f8f3d1be;hp=13ced0f7828f477d6edc6356dcdfd7e8617cb567;hpb=b8c475be7bf9b79e6417c08d7a921b2e8cb04258;p=linux-2.6 diff --git a/kernel/printk.c b/kernel/printk.c index 13ced0f782..95b7fe17f1 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -24,6 +24,7 @@ #include #include #include +#include #include /* For in_interrupt() */ #include #include @@ -67,6 +68,7 @@ EXPORT_SYMBOL(oops_in_progress); * driver system. */ static DECLARE_MUTEX(console_sem); +static DECLARE_MUTEX(secondary_console_sem); struct console *console_drivers; /* * This is used for debugging the mess that is the VT code by @@ -76,7 +78,7 @@ struct console *console_drivers; * path in the console code where we end up in places I want * locked without the console sempahore held */ -static int console_locked; +static int console_locked, console_suspended; /* * logbuf_lock protects log_buf, log_start, log_end, con_start and logged_chars @@ -122,44 +124,6 @@ static char *log_buf = __log_buf; static int log_buf_len = __LOG_BUF_LEN; static unsigned long logged_chars; /* Number of chars produced since last read+clear operation */ -/* - * Setup a list of consoles. Called from init/main.c - */ -static int __init console_setup(char *str) -{ - char name[sizeof(console_cmdline[0].name)]; - char *s, *options; - int idx; - - /* - * Decode str into name, index, options. - */ - if (str[0] >= '0' && str[0] <= '9') { - strcpy(name, "ttyS"); - strncpy(name + 4, str, sizeof(name) - 5); - } else - strncpy(name, str, sizeof(name) - 1); - name[sizeof(name) - 1] = 0; - if ((options = strchr(str, ',')) != NULL) - *(options++) = 0; -#ifdef __sparc__ - if (!strcmp(str, "ttya")) - strcpy(name, "ttyS0"); - if (!strcmp(str, "ttyb")) - strcpy(name, "ttyS1"); -#endif - for (s = name; *s; s++) - if ((*s >= '0' && *s <= '9') || *s == ',') - break; - idx = simple_strtoul(s, NULL, 10); - *s = 0; - - add_preferred_console(name, idx, options); - return 1; -} - -__setup("console=", console_setup); - static int __init log_buf_len_setup(char *str) { unsigned long size = memparse(str, &str); @@ -364,7 +328,9 @@ 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); } } @@ -398,8 +364,7 @@ static void call_console_drivers(unsigned long start, unsigned long end) unsigned long cur_index, start_print; static int msg_level = -1; - if (((long)(start - end)) > 0) - BUG(); + BUG_ON(((long)(start - end)) > 0); cur_index = start; start_print = start; @@ -475,6 +440,7 @@ static int printk_time = 1; #else static int printk_time = 0; #endif +module_param(printk_time, int, S_IRUGO | S_IWUSR); static int __init printk_time_setup(char *str) { @@ -491,6 +457,18 @@ __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 @@ -604,27 +582,29 @@ 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 @@ -634,7 +614,7 @@ 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; } @@ -659,6 +639,44 @@ static void call_console_drivers(unsigned long start, unsigned long end) #endif +/* + * Set up a list of consoles. Called from init/main.c + */ +static int __init console_setup(char *str) +{ + char name[sizeof(console_cmdline[0].name)]; + char *s, *options; + int idx; + + /* + * Decode str into name, index, options. + */ + if (str[0] >= '0' && str[0] <= '9') { + strcpy(name, "ttyS"); + strncpy(name + 4, str, sizeof(name) - 5); + } else { + strncpy(name, str, sizeof(name) - 1); + } + name[sizeof(name) - 1] = 0; + if ((options = strchr(str, ',')) != NULL) + *(options++) = 0; +#ifdef __sparc__ + if (!strcmp(str, "ttya")) + strcpy(name, "ttyS0"); + if (!strcmp(str, "ttyb")) + strcpy(name, "ttyS1"); +#endif + for (s = name; *s; s++) + if ((*s >= '0' && *s <= '9') || *s == ',') + break; + idx = simple_strtoul(s, NULL, 10); + *s = 0; + + add_preferred_console(name, idx, options); + return 1; +} +__setup("console=", console_setup); + /** * add_preferred_console - add a device to the list of preferred consoles. * @name: device name @@ -698,6 +716,23 @@ int __init add_preferred_console(char *name, int idx, char *options) return 0; } +/** + * suspend_console - suspend the console subsystem + * + * This disables printk() while we go into suspend states + */ +void suspend_console(void) +{ + acquire_console_sem(); + console_suspended = 1; +} + +void resume_console(void) +{ + console_suspended = 0; + release_console_sem(); +} + /** * acquire_console_sem - lock the console system for exclusive use. * @@ -708,8 +743,11 @@ int __init add_preferred_console(char *name, int idx, char *options) */ void acquire_console_sem(void) { - if (in_interrupt()) - BUG(); + BUG_ON(in_interrupt()); + if (console_suspended) { + down(&secondary_console_sem); + return; + } down(&console_sem); console_locked = 1; console_may_schedule = 1; @@ -752,6 +790,10 @@ void release_console_sem(void) unsigned long _con_start, _log_end; unsigned long wake_klogd = 0; + if (console_suspended) { + up(&secondary_console_sem); + return; + } for ( ; ; ) { spin_lock_irqsave(&logbuf_lock, flags); wake_klogd |= log_start - log_end;