diff options
Diffstat (limited to 'kernel/printk')
| -rw-r--r-- | kernel/printk/printk.c | 28 |
1 files changed, 19 insertions, 9 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 7219991885e6..51445e8ea730 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -3118,14 +3118,24 @@ void console_unblank(void) */ void console_flush_on_panic(enum con_flush_mode mode) { + bool handover; + u64 next_seq; + /* - * 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. + * Ignore the console lock and flush out the messages. Attempting a + * trylock would not be useful because: + * + * - if it is contended, it must be ignored anyway + * - console_lock() and console_trylock() block and fail + * respectively in panic for non-panic CPUs + * - semaphores are not NMI-safe + */ + + /* + * If another context is holding the console lock, + * @console_may_schedule might be set. Clear it so that + * this context does not call cond_resched() while flushing. */ - console_trylock(); console_may_schedule = 0; if (mode == CONSOLE_REPLAY_ALL) { @@ -3138,15 +3148,15 @@ void console_flush_on_panic(enum con_flush_mode mode) cookie = console_srcu_read_lock(); for_each_console_srcu(c) { /* - * If the above console_trylock() failed, this is an - * unsynchronized assignment. But in that case, the + * This is an unsynchronized assignment, but the * kernel is in "hope and pray" mode anyway. */ c->seq = seq; } console_srcu_read_unlock(cookie); } - console_unlock(); + + console_flush_all(false, &next_seq, &handover); } /* |