diff options
Diffstat (limited to 'kernel/printk.c')
| -rw-r--r-- | kernel/printk.c | 127 |
1 files changed, 125 insertions, 2 deletions
diff --git a/kernel/printk.c b/kernel/printk.c index 8451dfc31d2..a30fe33de39 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -22,6 +22,8 @@ #include <linux/tty_driver.h> #include <linux/console.h> #include <linux/init.h> +#include <linux/jiffies.h> +#include <linux/nmi.h> #include <linux/module.h> #include <linux/moduleparam.h> #include <linux/interrupt.h> /* For in_interrupt() */ @@ -162,6 +164,113 @@ out: __setup("log_buf_len=", log_buf_len_setup); +#ifdef CONFIG_BOOT_PRINTK_DELAY + +static unsigned int boot_delay; /* msecs delay after each printk during bootup */ +static unsigned long long printk_delay_msec; /* per msec, based on boot_delay */ + +static int __init boot_delay_setup(char *str) +{ + unsigned long lpj; + unsigned long long loops_per_msec; + + lpj = preset_lpj ? preset_lpj : 1000000; /* some guess */ + loops_per_msec = (unsigned long long)lpj / 1000 * HZ; + + get_option(&str, &boot_delay); + if (boot_delay > 10 * 1000) + boot_delay = 0; + + printk_delay_msec = loops_per_msec; + printk(KERN_DEBUG "boot_delay: %u, preset_lpj: %ld, lpj: %lu, " + "HZ: %d, printk_delay_msec: %llu\n", + boot_delay, preset_lpj, lpj, HZ, printk_delay_msec); + return 1; +} +__setup("boot_delay=", boot_delay_setup); + +static void boot_delay_msec(void) +{ + unsigned long long k; + unsigned long timeout; + + if (boot_delay == 0 || system_state != SYSTEM_BOOTING) + return; + + k = (unsigned long long)printk_delay_msec * boot_delay; + + timeout = jiffies + msecs_to_jiffies(boot_delay); + while (k) { + k--; + cpu_relax(); + /* + * use (volatile) jiffies to prevent + * compiler reduction; loop termination via jiffies + * is secondary and may or may not happen. + */ + if (time_after(jiffies, timeout)) + break; + touch_nmi_watchdog(); + } +} +#else +static inline void boot_delay_msec(void) +{ +} +#endif + +/* + * Return the number of unread characters in the log buffer. + */ +int log_buf_get_len(void) +{ + return logged_chars; +} + +/* + * Copy a range of characters from the log buffer. + */ +int log_buf_copy(char *dest, int idx, int len) +{ + int ret, max; + bool took_lock = false; + + if (!oops_in_progress) { + spin_lock_irq(&logbuf_lock); + took_lock = true; + } + + max = log_buf_get_len(); + if (idx < 0 || idx >= max) { + ret = -1; + } else { + if (len > max) + len = max; + ret = len; + idx += (log_end - max); + while (len-- > 0) + dest[len] = LOG_BUF(idx + len); + } + + if (took_lock) + spin_unlock_irq(&logbuf_lock); + + return ret; +} + +/* + * Extract a single character from the log buffer. + */ +int log_buf_read(int idx) +{ + char ret; + + if (log_buf_copy(&ret, idx, 1) == 1) + return ret; + else + return -1; +} + /* * Commands to do_syslog: * @@ -527,6 +636,8 @@ asmlinkage int vprintk(const char *fmt, va_list args) static char printk_buf[1024]; static int log_level_unknown = 1; + boot_delay_msec(); + preempt_disable(); if (unlikely(oops_in_progress) && printk_cpu == smp_processor_id()) /* If a crash is occurring during printk() on this CPU, @@ -751,7 +862,16 @@ int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, cha return -1; } -#ifndef CONFIG_DISABLE_CONSOLE_SUSPEND +int console_suspend_enabled = 1; +EXPORT_SYMBOL(console_suspend_enabled); + +static int __init console_suspend_disable(char *str) +{ + console_suspend_enabled = 0; + return 1; +} +__setup("no_console_suspend", console_suspend_disable); + /** * suspend_console - suspend the console subsystem * @@ -759,6 +879,8 @@ int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, cha */ void suspend_console(void) { + if (!console_suspend_enabled) + return; printk("Suspending console(s)\n"); acquire_console_sem(); console_suspended = 1; @@ -766,10 +888,11 @@ void suspend_console(void) void resume_console(void) { + if (!console_suspend_enabled) + return; console_suspended = 0; release_console_sem(); } -#endif /* CONFIG_DISABLE_CONSOLE_SUSPEND */ /** * acquire_console_sem - lock the console system for exclusive use. |