diff options
| -rw-r--r-- | kernel/printk/internal.h | 73 | ||||
| -rw-r--r-- | kernel/printk/nbcon.c | 12 | ||||
| -rw-r--r-- | kernel/printk/printk.c | 68 |
3 files changed, 112 insertions, 41 deletions
diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h index 6b61350a3026..ba2e0f1940bd 100644 --- a/kernel/printk/internal.h +++ b/kernel/printk/internal.h @@ -154,8 +154,81 @@ static inline bool console_is_usable(struct console *con, short flags) { return #endif /* CONFIG_PRINTK */ extern bool have_boot_console; +extern bool have_nbcon_console; +extern bool have_legacy_console; extern bool legacy_allow_panic_sync; +/** + * struct console_flush_type - Define available console flush methods + * @nbcon_atomic: Flush directly using nbcon_atomic() callback + * @legacy_direct: Call the legacy loop in this context + * @legacy_offload: Offload the legacy loop into IRQ + * + * Note that the legacy loop also flushes the nbcon consoles. + */ +struct console_flush_type { + bool nbcon_atomic; + bool legacy_direct; + bool legacy_offload; +}; + +/* + * Identify which console flushing methods should be used in the context of + * the caller. + */ +static inline void printk_get_console_flush_type(struct console_flush_type *ft) +{ + memset(ft, 0, sizeof(*ft)); + + switch (nbcon_get_default_prio()) { + case NBCON_PRIO_NORMAL: + if (have_nbcon_console && !have_boot_console) + ft->nbcon_atomic = true; + + /* Legacy consoles are flushed directly when possible. */ + if (have_legacy_console || have_boot_console) { + if (!is_printk_legacy_deferred()) + ft->legacy_direct = true; + else + ft->legacy_offload = true; + } + break; + + case NBCON_PRIO_PANIC: + /* + * In panic, the nbcon consoles will directly print. But + * only allowed if there are no boot consoles. + */ + if (have_nbcon_console && !have_boot_console) + ft->nbcon_atomic = true; + + if (have_legacy_console || have_boot_console) { + /* + * This is the same decision as NBCON_PRIO_NORMAL + * except that offloading never occurs in panic. + * + * Note that console_flush_on_panic() will flush + * legacy consoles anyway, even if unsafe. + */ + if (!is_printk_legacy_deferred()) + ft->legacy_direct = true; + + /* + * In panic, if nbcon atomic printing occurs, + * the legacy consoles must remain silent until + * explicitly allowed. + */ + if (ft->nbcon_atomic && !legacy_allow_panic_sync) + ft->legacy_direct = false; + } + break; + + default: + WARN_ON_ONCE(1); + break; + } +} + extern struct printk_buffers printk_shared_pbufs; /** diff --git a/kernel/printk/nbcon.c b/kernel/printk/nbcon.c index afdb16c1c733..18488d6c17c0 100644 --- a/kernel/printk/nbcon.c +++ b/kernel/printk/nbcon.c @@ -1344,6 +1344,7 @@ EXPORT_SYMBOL_GPL(nbcon_device_try_acquire); void nbcon_device_release(struct console *con) { struct nbcon_context *ctxt = &ACCESS_PRIVATE(con, nbcon_device_ctxt); + struct console_flush_type ft; int cookie; if (!nbcon_context_exit_unsafe(ctxt)) @@ -1359,12 +1360,17 @@ void nbcon_device_release(struct console *con) cookie = console_srcu_read_lock(); if (console_is_usable(con, console_srcu_read_flags(con)) && prb_read_valid(prb, nbcon_seq_read(con), NULL)) { - if (!have_boot_console) { + /* + * If nbcon_atomic flushing is not available, fallback to + * using the legacy loop. + */ + printk_get_console_flush_type(&ft); + if (ft.nbcon_atomic) { __nbcon_atomic_flush_pending_con(con, prb_next_reserve_seq(prb), false); - } else if (!is_printk_legacy_deferred()) { + } else if (ft.legacy_direct) { if (console_trylock()) console_unlock(); - } else { + } else if (ft.legacy_offload) { printk_trigger_flush(); } } diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index fc3f8970eea2..6accd1704e73 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -468,14 +468,14 @@ static DEFINE_MUTEX(syslog_lock); * present, it is necessary to perform the console lock/unlock dance * whenever console flushing should occur. */ -static bool have_legacy_console; +bool have_legacy_console; /* * Specifies if an nbcon console is registered. If nbcon consoles are present, * synchronous printing of legacy consoles will not occur during panic until * the backtrace has been stored to the ringbuffer. */ -static bool have_nbcon_console; +bool have_nbcon_console; /* * Specifies if a boot console is registered. If boot consoles are present, @@ -488,14 +488,6 @@ bool have_boot_console; /* See printk_legacy_allow_panic_sync() for details. */ bool legacy_allow_panic_sync; -/* - * Specifies if the console lock/unlock dance is needed for console - * printing. If @have_boot_console is true, the nbcon consoles will - * be printed serially along with the legacy consoles because nbcon - * consoles cannot print simultaneously with boot consoles. - */ -#define printing_via_unlock (have_legacy_console || have_boot_console) - #ifdef CONFIG_PRINTK DECLARE_WAIT_QUEUE_HEAD(log_wait); /* All 3 protected by @syslog_lock. */ @@ -2342,9 +2334,12 @@ out: */ void printk_legacy_allow_panic_sync(void) { + struct console_flush_type ft; + legacy_allow_panic_sync = true; - if (printing_via_unlock && !is_printk_legacy_deferred()) { + printk_get_console_flush_type(&ft); + if (ft.legacy_direct) { if (console_trylock()) console_unlock(); } @@ -2354,8 +2349,7 @@ asmlinkage int vprintk_emit(int facility, int level, const struct dev_printk_info *dev_info, const char *fmt, va_list args) { - bool do_trylock_unlock = printing_via_unlock; - bool defer_legacy = false; + struct console_flush_type ft; int printed_len; /* Suppress unimportant messages after panic happens */ @@ -2370,35 +2364,23 @@ asmlinkage int vprintk_emit(int facility, int level, if (other_cpu_in_panic() && !panic_triggering_all_cpu_backtrace) return 0; + printk_get_console_flush_type(&ft); + /* If called from the scheduler, we can not call up(). */ if (level == LOGLEVEL_SCHED) { level = LOGLEVEL_DEFAULT; - defer_legacy = do_trylock_unlock; - do_trylock_unlock = false; + ft.legacy_offload |= ft.legacy_direct; + ft.legacy_direct = false; } printk_delay(level); printed_len = vprintk_store(facility, level, dev_info, fmt, args); - if (have_nbcon_console && !have_boot_console) { + if (ft.nbcon_atomic) nbcon_atomic_flush_pending(); - /* - * In panic, the legacy consoles are not allowed to print from - * the printk calling context unless explicitly allowed. This - * gives the safe nbcon consoles a chance to print out all the - * panic messages first. This restriction only applies if - * there are nbcon consoles registered and they are allowed to - * flush. - */ - if (this_cpu_in_panic() && !legacy_allow_panic_sync) { - do_trylock_unlock = false; - defer_legacy = false; - } - } - - if (do_trylock_unlock) { + if (ft.legacy_direct) { /* * The caller may be holding system-critical or * timing-sensitive locks. Disable preemption during @@ -2418,7 +2400,7 @@ asmlinkage int vprintk_emit(int facility, int level, preempt_enable(); } - if (defer_legacy) + if (ft.legacy_offload) defer_console_output(); else wake_up_klogd(); @@ -2777,10 +2759,16 @@ void resume_console(void) */ static int console_cpu_notify(unsigned int cpu) { - if (!cpuhp_tasks_frozen && printing_via_unlock) { - /* If trylock fails, someone else is doing the printing */ - if (console_trylock()) - console_unlock(); + struct console_flush_type ft; + + if (!cpuhp_tasks_frozen) { + printk_get_console_flush_type(&ft); + if (ft.nbcon_atomic) + nbcon_atomic_flush_pending(); + if (ft.legacy_direct) { + if (console_trylock()) + console_unlock(); + } } return 0; } @@ -3305,6 +3293,7 @@ static void __console_rewind_all(void) */ void console_flush_on_panic(enum con_flush_mode mode) { + struct console_flush_type ft; bool handover; u64 next_seq; @@ -3328,7 +3317,8 @@ void console_flush_on_panic(enum con_flush_mode mode) if (mode == CONSOLE_REPLAY_ALL) __console_rewind_all(); - if (!have_boot_console) + printk_get_console_flush_type(&ft); + if (ft.nbcon_atomic) nbcon_atomic_flush_pending(); /* Flush legacy consoles once allowed, even when dangerous. */ @@ -3992,6 +3982,7 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre { unsigned long timeout_jiffies = msecs_to_jiffies(timeout_ms); unsigned long remaining_jiffies = timeout_jiffies; + struct console_flush_type ft; struct console *c; u64 last_diff = 0; u64 printk_seq; @@ -4005,7 +3996,8 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre seq = prb_next_reserve_seq(prb); /* Flush the consoles so that records up to @seq are printed. */ - if (printing_via_unlock) { + printk_get_console_flush_type(&ft); + if (ft.legacy_direct) { console_lock(); console_unlock(); } |