X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=kernel%2Fprintk.c;h=29ae1e99cde08b247aa106a2939496abf3b3c871;hb=02d90fc343411d6dff26bbd64f0895a243e6f608;hp=b2b5c3a22a36b302da177fafae653740f7eeeddf;hpb=ebc283118ee448dcb6e6cae74a8a43f17a1ccc3f;p=linux-2.6 diff --git a/kernel/printk.c b/kernel/printk.c index b2b5c3a22a..29ae1e99cd 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -36,6 +36,13 @@ #include +/* + * Architectures can override it: + */ +void __attribute__((weak)) early_printk(const char *fmt, ...) +{ +} + #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) /* printk's without a loglevel use this.. */ @@ -219,6 +226,58 @@ 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: * @@ -396,10 +455,10 @@ static int __init ignore_loglevel_setup(char *str) ignore_loglevel = 1; printk(KERN_INFO "debug: ignoring loglevel setting.\n"); - return 1; + return 0; } -__setup("ignore_loglevel", ignore_loglevel_setup); +early_param("ignore_loglevel", ignore_loglevel_setup); /* * Write out chars from start to end - 1 inclusive @@ -521,11 +580,6 @@ static int __init printk_time_setup(char *str) __setup("time", printk_time_setup); -__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) { @@ -576,30 +630,57 @@ asmlinkage int printk(const char *fmt, ...) /* cpu currently holding logbuf_lock */ static volatile unsigned int printk_cpu = UINT_MAX; +const char printk_recursion_bug_msg [] = + KERN_CRIT "BUG: recent printk recursion!\n"; +static int printk_recursion_bug; + asmlinkage int vprintk(const char *fmt, va_list args) { + static int log_level_unknown = 1; + static char printk_buf[1024]; + unsigned long flags; - int printed_len; + int printed_len = 0; + int this_cpu; char *p; - 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, - * make sure we can't deadlock */ - zap_locks(); - /* This stops the holder of console_sem just where we want him */ raw_local_irq_save(flags); + this_cpu = smp_processor_id(); + + /* + * Ouch, printk recursed into itself! + */ + if (unlikely(printk_cpu == this_cpu)) { + /* + * If a crash is occurring during printk() on this CPU, + * then try to get the crash message out but make sure + * we can't deadlock. Otherwise just return to avoid the + * recursion and return - but flag the recursion so that + * it can be printed at the next appropriate moment: + */ + if (!oops_in_progress) { + printk_recursion_bug = 1; + goto out_restore_irqs; + } + zap_locks(); + } + lockdep_off(); spin_lock(&logbuf_lock); - printk_cpu = smp_processor_id(); + printk_cpu = this_cpu; + if (printk_recursion_bug) { + printk_recursion_bug = 0; + strcpy(printk_buf, printk_recursion_bug_msg); + printed_len = sizeof(printk_recursion_bug_msg); + } /* Emit the output into the temporary buffer */ - printed_len = vscnprintf(printk_buf, sizeof(printk_buf), fmt, args); + printed_len += vscnprintf(printk_buf + printed_len, + sizeof(printk_buf), fmt, args); /* * Copy the output into log_buf. If the caller didn't provide @@ -628,7 +709,7 @@ asmlinkage int vprintk(const char *fmt, va_list args) loglev_char = default_message_loglevel + '0'; } - t = printk_clock(); + t = cpu_clock(printk_cpu); nanosec_rem = do_div(t, 1000000000); tlen = sprintf(tbuf, "<%c>[%5lu.%06lu] ", @@ -692,6 +773,7 @@ asmlinkage int vprintk(const char *fmt, va_list args) printk_cpu = UINT_MAX; spin_unlock(&logbuf_lock); lockdep_on(); +out_restore_irqs: raw_local_irq_restore(flags); } @@ -765,7 +847,7 @@ __setup("console=", console_setup); * commonly to provide a default console (ie from PROM variables) when * the user has not supplied one. */ -int __init add_preferred_console(char *name, int idx, char *options) +int add_preferred_console(char *name, int idx, char *options) { struct console_cmdline *c; int i; @@ -810,7 +892,16 @@ 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 * @@ -818,6 +909,8 @@ 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; @@ -825,10 +918,11 @@ 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.