diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/printk.c | 48 |
1 files changed, 38 insertions, 10 deletions
diff --git a/kernel/printk.c b/kernel/printk.c index 89011bf8c10..e6c1f36d8c3 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -628,30 +628,57 @@ 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 @@ -744,6 +771,7 @@ 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); } |