diff options
Diffstat (limited to 'kernel/printk/printk.c')
| -rw-r--r-- | kernel/printk/printk.c | 83 |
1 files changed, 63 insertions, 20 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index fada22dc4ab6..9a9b6156270b 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -460,6 +460,18 @@ static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); static char *log_buf = __log_buf; static u32 log_buf_len = __LOG_BUF_LEN; +/* + * We cannot access per-CPU data (e.g. per-CPU flush irq_work) before + * per_cpu_areas are initialised. This variable is set to true when + * it's safe to access per-CPU data. + */ +static bool __printk_percpu_data_ready __read_mostly; + +bool printk_percpu_data_ready(void) +{ + return __printk_percpu_data_ready; +} + /* Return log buffer address */ char *log_buf_addr_get(void) { @@ -1146,12 +1158,28 @@ static void __init log_buf_add_cpu(void) static inline void log_buf_add_cpu(void) {} #endif /* CONFIG_SMP */ +static void __init set_percpu_data_ready(void) +{ + printk_safe_init(); + /* Make sure we set this flag only after printk_safe() init is done */ + barrier(); + __printk_percpu_data_ready = true; +} + void __init setup_log_buf(int early) { unsigned long flags; char *new_log_buf; unsigned int free; + /* + * Some archs call setup_log_buf() multiple times - first is very + * early, e.g. from setup_arch(), and second - when percpu_areas + * are initialised. + */ + if (!early) + set_percpu_data_ready(); + if (log_buf != __log_buf) return; @@ -1772,9 +1800,6 @@ static void call_console_drivers(const char *ext_text, size_t ext_len, trace_console_rcuidle(text, len); - if (!console_drivers) - return; - for_each_console(con) { if (exclusive_console && con != exclusive_console) continue; @@ -2653,19 +2678,17 @@ void register_console(struct console *newcon) struct console_cmdline *c; static bool has_preferred; - if (console_drivers) - for_each_console(bcon) - if (WARN(bcon == newcon, - "console '%s%d' already registered\n", - bcon->name, bcon->index)) - return; + for_each_console(bcon) { + if (WARN(bcon == newcon, "console '%s%d' already registered\n", + bcon->name, bcon->index)) + return; + } /* * before we register a new CON_BOOT console, make sure we don't * already have a valid console */ - if (console_drivers && newcon->flags & CON_BOOT) { - /* find the last or real console */ + if (newcon->flags & CON_BOOT) { for_each_console(bcon) { if (!(bcon->flags & CON_BOOT)) { pr_info("Too late to register bootconsole %s%d\n", @@ -2813,7 +2836,7 @@ EXPORT_SYMBOL(register_console); int unregister_console(struct console *console) { - struct console *a, *b; + struct console *con; int res; pr_info("%sconsole [%s%d] disabled\n", @@ -2821,26 +2844,30 @@ int unregister_console(struct console *console) console->name, console->index); res = _braille_unregister_console(console); - if (res) + if (res < 0) return res; + if (res > 0) + return 0; - res = 1; + res = -ENODEV; console_lock(); if (console_drivers == console) { console_drivers=console->next; res = 0; - } else if (console_drivers) { - for (a=console_drivers->next, b=console_drivers ; - a; b=a, a=b->next) { - if (a == console) { - b->next = a->next; + } else { + for_each_console(con) { + if (con->next == console) { + con->next = console->next; res = 0; break; } } } - if (!res && (console->flags & CON_EXTENDED)) + if (res) + goto out_disable_unlock; + + if (console->flags & CON_EXTENDED) nr_ext_console_drivers--; /* @@ -2853,6 +2880,16 @@ int unregister_console(struct console *console) console->flags &= ~CON_ENABLED; console_unlock(); console_sysfs_notify(); + + if (console->exit) + res = console->exit(console); + + return res; + +out_disable_unlock: + console->flags &= ~CON_ENABLED; + console_unlock(); + return res; } EXPORT_SYMBOL(unregister_console); @@ -2966,6 +3003,9 @@ static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = { void wake_up_klogd(void) { + if (!printk_percpu_data_ready()) + return; + preempt_disable(); if (waitqueue_active(&log_wait)) { this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP); @@ -2976,6 +3016,9 @@ void wake_up_klogd(void) void defer_console_output(void) { + if (!printk_percpu_data_ready()) + return; + preempt_disable(); __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); |