diff options
Diffstat (limited to 'kernel/printk/printk.c')
| -rw-r--r-- | kernel/printk/printk.c | 51 |
1 files changed, 44 insertions, 7 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 28fb44dccbad..9fcb521fab0e 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -236,7 +236,11 @@ struct printk_log { u8 facility; /* syslog facility */ u8 flags:5; /* internal record flags */ u8 level:3; /* syslog level */ -}; +} +#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS +__packed __aligned(4) +#endif +; /* * The logbuf_lock protects kmsg buffer, indices, counters. This can be taken @@ -277,11 +281,7 @@ static u32 clear_idx; #define LOG_FACILITY(v) ((v) >> 3 & 0xff) /* record buffer */ -#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) -#define LOG_ALIGN 4 -#else #define LOG_ALIGN __alignof__(struct printk_log) -#endif #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); static char *log_buf = __log_buf; @@ -1440,7 +1440,7 @@ static void call_console_drivers(int level, { struct console *con; - trace_console(text, len); + trace_console_rcuidle(text, len); if (level >= console_loglevel && !ignore_loglevel) return; @@ -2138,8 +2138,12 @@ static int console_cpu_notify(struct notifier_block *self, case CPU_DEAD: case CPU_DOWN_FAILED: case CPU_UP_CANCELED: + case CPU_DYING: +#ifdef CONFIG_CONSOLE_FLUSH_ON_HOTPLUG console_lock(); console_unlock(); +#endif + break; } return NOTIFY_OK; } @@ -2241,13 +2245,24 @@ void console_unlock(void) static u64 seen_seq; unsigned long flags; bool wake_klogd = false; - bool retry; + bool do_cond_resched, retry; if (console_suspended) { up_console_sem(); return; } + /* + * Console drivers are called under logbuf_lock, so + * @console_may_schedule should be cleared before; however, we may + * end up dumping a lot of lines, for example, if called from + * console registration path, and should invoke cond_resched() + * between lines if allowable. Not doing so can cause a very long + * scheduling stall on a slow console leading to RCU stall and + * softlockup warnings which exacerbate the issue with more + * messages practically incapacitating the system. + */ + do_cond_resched = console_may_schedule; console_may_schedule = 0; /* flush buffered message fragment immediately to console */ @@ -2319,6 +2334,9 @@ skip: call_console_drivers(level, ext_text, ext_len, text, len); start_critical_timings(); local_irq_restore(flags); + + if (do_cond_resched) + cond_resched(); } console_locked = 0; @@ -2386,6 +2404,25 @@ void console_unblank(void) console_unlock(); } +/** + * console_flush_on_panic - flush console content on panic + * + * Immediately output all pending messages no matter what. + */ +void console_flush_on_panic(void) +{ + /* + * If someone else is holding the console lock, trylock will fail + * and may_schedule may be set. Ignore and proceed to unlock so + * that messages are flushed out. As this can be called from any + * context and we don't want to get preempted while flushing, + * ensure may_schedule is cleared. + */ + console_trylock(); + console_may_schedule = 0; + console_unlock(); +} + /* * Return the console tty driver structure and its associated index */ |