diff options
| -rw-r--r-- | kernel/printk/printk.c | 47 |
1 files changed, 32 insertions, 15 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 6bb77eff502d..f426a2b12a9b 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -213,17 +213,36 @@ static int nr_ext_console_drivers; static int __down_trylock_console_sem(unsigned long ip) { - if (down_trylock(&console_sem)) + int lock_failed; + unsigned long flags; + + /* + * Here and in __up_console_sem() we need to be in safe mode, + * because spindump/WARN/etc from under console ->lock will + * deadlock in printk()->down_trylock_console_sem() otherwise. + */ + printk_safe_enter_irqsave(flags); + lock_failed = down_trylock(&console_sem); + printk_safe_exit_irqrestore(flags); + + if (lock_failed) return 1; mutex_acquire(&console_lock_dep_map, 0, 1, ip); return 0; } #define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_) -#define up_console_sem() do { \ - mutex_release(&console_lock_dep_map, 1, _RET_IP_);\ - up(&console_sem);\ -} while (0) +static void __up_console_sem(unsigned long ip) +{ + unsigned long flags; + + mutex_release(&console_lock_dep_map, 1, ip); + + printk_safe_enter_irqsave(flags); + up(&console_sem); + printk_safe_exit_irqrestore(flags); +} +#define up_console_sem() __up_console_sem(_RET_IP_) /* * This is used for debugging the mess that is the VT code by @@ -1689,7 +1708,7 @@ asmlinkage int vprintk_emit(int facility, int level, boot_delay_msec(level); printk_delay(); - local_irq_save(flags); + printk_safe_enter_irqsave(flags); this_cpu = smp_processor_id(); /* @@ -1705,13 +1724,12 @@ asmlinkage int vprintk_emit(int facility, int level, */ if (!oops_in_progress && !lockdep_recursing(current)) { recursion_bug = true; - local_irq_restore(flags); + printk_safe_exit_irqrestore(flags); return 0; } zap_locks(); } - lockdep_off(); /* This stops the holder of console_sem just where we want him */ raw_spin_lock(&logbuf_lock); logbuf_cpu = this_cpu; @@ -1771,12 +1789,10 @@ asmlinkage int vprintk_emit(int facility, int level, logbuf_cpu = UINT_MAX; raw_spin_unlock(&logbuf_lock); - lockdep_on(); - local_irq_restore(flags); + printk_safe_exit_irqrestore(flags); /* If called from the scheduler, we can not call up(). */ if (!in_sched) { - lockdep_off(); /* * Try to acquire and then immediately release the console * semaphore. The release will print out buffers and wake up @@ -1784,7 +1800,6 @@ asmlinkage int vprintk_emit(int facility, int level, */ if (console_trylock()) console_unlock(); - lockdep_on(); } return printed_len; @@ -2209,7 +2224,8 @@ again: size_t len; int level; - raw_spin_lock_irqsave(&logbuf_lock, flags); + printk_safe_enter_irqsave(flags); + raw_spin_lock(&logbuf_lock); if (seen_seq != log_next_seq) { wake_klogd = true; seen_seq = log_next_seq; @@ -2259,7 +2275,7 @@ skip: stop_critical_timings(); /* don't trace print latency */ call_console_drivers(level, ext_text, ext_len, text, len); start_critical_timings(); - local_irq_restore(flags); + printk_safe_exit_irqrestore(flags); if (do_cond_resched) cond_resched(); @@ -2282,7 +2298,8 @@ skip: */ raw_spin_lock(&logbuf_lock); retry = console_seq != log_next_seq; - raw_spin_unlock_irqrestore(&logbuf_lock, flags); + raw_spin_unlock(&logbuf_lock); + printk_safe_exit_irqrestore(flags); if (retry && console_trylock()) goto again; |