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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright (c) 2010 Werner Fink, Jiri Slaby4 */5 6#include <linux/console.h>7#include <linux/kernel.h>8#include <linux/proc_fs.h>9#include <linux/seq_file.h>10#include <linux/tty_driver.h>11 12/*13 * This is handler for /proc/consoles14 */15static int show_console_dev(struct seq_file *m, void *v)16{17 static const struct {18 short flag;19 char name;20 } con_flags[] = {21 { CON_ENABLED, 'E' },22 { CON_CONSDEV, 'C' },23 { CON_BOOT, 'B' },24 { CON_NBCON, 'N' },25 { CON_PRINTBUFFER, 'p' },26 { CON_BRL, 'b' },27 { CON_ANYTIME, 'a' },28 };29 char flags[ARRAY_SIZE(con_flags) + 1];30 struct console *con = v;31 unsigned int a;32 dev_t dev = 0;33 34 if (con->device) {35 const struct tty_driver *driver;36 int index;37 38 /*39 * Take console_lock to serialize device() callback with40 * other console operations. For example, fg_console is41 * modified under console_lock when switching vt.42 */43 console_lock();44 driver = con->device(con, &index);45 console_unlock();46 47 if (driver) {48 dev = MKDEV(driver->major, driver->minor_start);49 dev += index;50 }51 }52 53 for (a = 0; a < ARRAY_SIZE(con_flags); a++)54 flags[a] = (con->flags & con_flags[a].flag) ?55 con_flags[a].name : ' ';56 flags[a] = 0;57 58 seq_setwidth(m, 21 - 1);59 seq_printf(m, "%s%d", con->name, con->index);60 seq_pad(m, ' ');61 seq_printf(m, "%c%c%c (%s)", con->read ? 'R' : '-',62 ((con->flags & CON_NBCON) || con->write) ? 'W' : '-',63 con->unblank ? 'U' : '-', flags);64 if (dev)65 seq_printf(m, " %4d:%d", MAJOR(dev), MINOR(dev));66 67 seq_putc(m, '\n');68 return 0;69}70 71static void *c_start(struct seq_file *m, loff_t *pos)72 __acquires(&console_mutex)73{74 struct console *con;75 loff_t off = 0;76 77 /*78 * Hold the console_list_lock to guarantee safe traversal of the79 * console list. SRCU cannot be used because there is no80 * place to store the SRCU cookie.81 */82 console_list_lock();83 for_each_console(con)84 if (off++ == *pos)85 break;86 87 return con;88}89 90static void *c_next(struct seq_file *m, void *v, loff_t *pos)91{92 struct console *con = v;93 94 ++*pos;95 return hlist_entry_safe(con->node.next, struct console, node);96}97 98static void c_stop(struct seq_file *m, void *v)99 __releases(&console_mutex)100{101 console_list_unlock();102}103 104static const struct seq_operations consoles_op = {105 .start = c_start,106 .next = c_next,107 .stop = c_stop,108 .show = show_console_dev109};110 111static int __init proc_consoles_init(void)112{113 proc_create_seq("consoles", 0, NULL, &consoles_op);114 return 0;115}116fs_initcall(proc_consoles_init);117