diff options
Diffstat (limited to 'kernel/printk/printk.c')
| -rw-r--r-- | kernel/printk/printk.c | 83 |
1 files changed, 66 insertions, 17 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index fed98a18e830..54ea492d0c97 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -462,6 +462,9 @@ bool have_boot_console; /* See printk_legacy_allow_panic_sync() for details. */ bool legacy_allow_panic_sync; +/* Avoid using irq_work when suspending. */ +bool console_irqwork_blocked; + #ifdef CONFIG_PRINTK DECLARE_WAIT_QUEUE_HEAD(log_wait); static DECLARE_WAIT_QUEUE_HEAD(legacy_wait); @@ -2390,7 +2393,7 @@ asmlinkage int vprintk_emit(int facility, int level, /* If called from the scheduler, we can not call up(). */ if (level == LOGLEVEL_SCHED) { level = LOGLEVEL_DEFAULT; - ft.legacy_offload |= ft.legacy_direct; + ft.legacy_offload |= ft.legacy_direct && !console_irqwork_blocked; ft.legacy_direct = false; } @@ -2426,7 +2429,7 @@ asmlinkage int vprintk_emit(int facility, int level, if (ft.legacy_offload) defer_console_output(); - else + else if (!console_irqwork_blocked) wake_up_klogd(); return printed_len; @@ -2730,10 +2733,20 @@ void console_suspend_all(void) { struct console *con; + if (console_suspend_enabled) + pr_info("Suspending console(s) (use no_console_suspend to debug)\n"); + + /* + * Flush any console backlog and then avoid queueing irq_work until + * console_resume_all(). Until then deferred printing is no longer + * triggered, NBCON consoles transition to atomic flushing, and + * any klogd waiters are not triggered. + */ + pr_flush(1000, true); + console_irqwork_blocked = true; + if (!console_suspend_enabled) return; - pr_info("Suspending console(s) (use no_console_suspend to debug)\n"); - pr_flush(1000, true); console_list_lock(); for_each_console(con) @@ -2754,26 +2767,34 @@ void console_resume_all(void) struct console_flush_type ft; struct console *con; - if (!console_suspend_enabled) - return; - - console_list_lock(); - for_each_console(con) - console_srcu_write_flags(con, con->flags & ~CON_SUSPENDED); - console_list_unlock(); - /* - * Ensure that all SRCU list walks have completed. All printing - * contexts must be able to see they are no longer suspended so - * that they are guaranteed to wake up and resume printing. + * Allow queueing irq_work. After restoring console state, deferred + * printing and any klogd waiters need to be triggered in case there + * is now a console backlog. */ - synchronize_srcu(&console_srcu); + console_irqwork_blocked = false; + + if (console_suspend_enabled) { + console_list_lock(); + for_each_console(con) + console_srcu_write_flags(con, con->flags & ~CON_SUSPENDED); + console_list_unlock(); + + /* + * Ensure that all SRCU list walks have completed. All printing + * contexts must be able to see they are no longer suspended so + * that they are guaranteed to wake up and resume printing. + */ + synchronize_srcu(&console_srcu); + } printk_get_console_flush_type(&ft); if (ft.nbcon_offload) nbcon_kthreads_wake(); if (ft.legacy_offload) defer_console_output(); + else + wake_up_klogd(); pr_flush(1000, true); } @@ -4559,6 +4580,13 @@ static void __wake_up_klogd(int val) if (!printk_percpu_data_ready()) return; + /* + * It is not allowed to call this function when console irq_work + * is blocked. + */ + if (WARN_ON_ONCE(console_irqwork_blocked)) + return; + preempt_disable(); /* * Guarantee any new records can be seen by tasks preparing to wait @@ -4615,9 +4643,30 @@ void defer_console_output(void) __wake_up_klogd(PRINTK_PENDING_WAKEUP | PRINTK_PENDING_OUTPUT); } +/** + * printk_trigger_flush - Attempt to flush printk buffer to consoles. + * + * If possible, flush the printk buffer to all consoles in the caller's + * context. If offloading is available, trigger deferred printing. + * + * This is best effort. Depending on the system state, console states, + * and caller context, no actual flushing may result from this call. + */ void printk_trigger_flush(void) { - defer_console_output(); + struct console_flush_type ft; + + printk_get_console_flush_type(&ft); + if (ft.nbcon_atomic) + nbcon_atomic_flush_pending(); + if (ft.nbcon_offload) + nbcon_kthreads_wake(); + if (ft.legacy_direct) { + if (console_trylock()) + console_unlock(); + } + if (ft.legacy_offload) + defer_console_output(); } int vprintk_deferred(const char *fmt, va_list args) |