diff options
| -rw-r--r-- | kernel/printk/printk.c | 81 |
1 files changed, 56 insertions, 25 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 2984fb0f0257..779479ac9f57 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -269,8 +269,8 @@ static struct console *exclusive_console; #define MAX_CMDLINECONSOLES 8 static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES]; +static int console_cmdline_cnt; -static int selected_console = -1; static int preferred_console = -1; int console_set_on_cmdline; EXPORT_SYMBOL(console_set_on_cmdline); @@ -1906,24 +1906,38 @@ static int __add_preferred_console(char *name, int idx, char *options, * See if this tty is not yet registered, and * if we have a slot free. */ - for (i = 0, c = console_cmdline; - i < MAX_CMDLINECONSOLES && c->name[0]; - i++, c++) { + for (i = 0, c = console_cmdline; i < console_cmdline_cnt; i++, c++) { if (strcmp(c->name, name) == 0 && c->index == idx) { - if (!brl_options) - selected_console = i; + if (brl_options) + return 0; + + /* + * Maintain an invariant that will help to find if + * the matching console is preferred, see + * register_console(): + * + * The last non-braille console is always + * the preferred one. + */ + if (i != console_cmdline_cnt - 1) + swap(console_cmdline[i], + console_cmdline[console_cmdline_cnt - 1]); + + preferred_console = console_cmdline_cnt - 1; + return 0; } } if (i == MAX_CMDLINECONSOLES) return -E2BIG; if (!brl_options) - selected_console = i; + preferred_console = i; strlcpy(c->name, name, sizeof(c->name)); c->options = options; braille_set_options(c, brl_options); c->index = idx; + console_cmdline_cnt++; return 0; } /* @@ -2031,15 +2045,16 @@ void resume_console(void) * @cpu: unused * * If printk() is called from a CPU that is not online yet, the messages - * will be spooled but will not show up on the console. This function is - * called when a new CPU comes online (or fails to come up), and ensures - * that any such output gets printed. + * will be printed on the console only if there are CON_ANYTIME consoles. + * This function is called when a new CPU comes online (or fails to come + * up) or goes offline. */ static int console_cpu_notify(unsigned int cpu) { if (!cpuhp_tasks_frozen) { - console_lock(); - console_unlock(); + /* If trylock fails, someone else is doing the printing */ + if (console_trylock()) + console_unlock(); } return 0; } @@ -2161,7 +2176,7 @@ void console_unlock(void) } /* - * Console drivers are called under logbuf_lock, so + * Console drivers are called with interrupts disabled, 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() @@ -2169,11 +2184,15 @@ void console_unlock(void) * scheduling stall on a slow console leading to RCU stall and * softlockup warnings which exacerbate the issue with more * messages practically incapacitating the system. + * + * console_trylock() is not able to detect the preemptive + * context reliably. Therefore the value must be stored before + * and cleared after the the "again" goto label. */ do_cond_resched = console_may_schedule; +again: console_may_schedule = 0; -again: /* * We released the console_sem lock, so we need to recheck if * cpu is online and (if not) is there at least one CON_ANYTIME @@ -2409,6 +2428,7 @@ void register_console(struct console *newcon) unsigned long flags; struct console *bcon = NULL; struct console_cmdline *c; + static bool has_preferred; if (console_drivers) for_each_console(bcon) @@ -2435,15 +2455,15 @@ void register_console(struct console *newcon) if (console_drivers && console_drivers->flags & CON_BOOT) bcon = console_drivers; - if (preferred_console < 0 || bcon || !console_drivers) - preferred_console = selected_console; + if (!has_preferred || bcon || !console_drivers) + has_preferred = preferred_console >= 0; /* * See if we want to use this console driver. If we * didn't select a console we take the first one * that registers here. */ - if (preferred_console < 0) { + if (!has_preferred) { if (newcon->index < 0) newcon->index = 0; if (newcon->setup == NULL || @@ -2451,18 +2471,29 @@ void register_console(struct console *newcon) newcon->flags |= CON_ENABLED; if (newcon->device) { newcon->flags |= CON_CONSDEV; - preferred_console = 0; + has_preferred = true; } } } /* - * See if this console matches one we selected on - * the command line. + * See if this console matches one we selected on the command line. + * + * There may be several entries in the console_cmdline array matching + * with the same console, one with newcon->match(), another by + * name/index: + * + * pl011,mmio,0x87e024000000,115200 -- added from SPCR + * ttyAMA0 -- added from command line + * + * Traverse the console_cmdline array in reverse order to be + * sure that if this console is preferred then it will be the first + * matching entry. We use the invariant that is maintained in + * __add_preferred_console(). */ - for (i = 0, c = console_cmdline; - i < MAX_CMDLINECONSOLES && c->name[0]; - i++, c++) { + for (i = console_cmdline_cnt - 1; i >= 0; i--) { + c = console_cmdline + i; + if (!newcon->match || newcon->match(newcon, c->name, c->index, c->options) != 0) { /* default matching */ @@ -2484,9 +2515,9 @@ void register_console(struct console *newcon) } newcon->flags |= CON_ENABLED; - if (i == selected_console) { + if (i == preferred_console) { newcon->flags |= CON_CONSDEV; - preferred_console = selected_console; + has_preferred = true; } break; } |