diff options
Diffstat (limited to 'fs/proc/consoles.c')
| -rw-r--r-- | fs/proc/consoles.c | 31 |
1 files changed, 24 insertions, 7 deletions
diff --git a/fs/proc/consoles.c b/fs/proc/consoles.c index 954caf0b7fee..b7cab1ad990d 100644 --- a/fs/proc/consoles.c +++ b/fs/proc/consoles.c @@ -1,7 +1,6 @@ +// SPDX-License-Identifier: GPL-2.0-only /* * Copyright (c) 2010 Werner Fink, Jiri Slaby - * - * Licensed under GPLv2 */ #include <linux/console.h> @@ -22,6 +21,7 @@ static int show_console_dev(struct seq_file *m, void *v) { CON_ENABLED, 'E' }, { CON_CONSDEV, 'C' }, { CON_BOOT, 'B' }, + { CON_NBCON, 'N' }, { CON_PRINTBUFFER, 'p' }, { CON_BRL, 'b' }, { CON_ANYTIME, 'a' }, @@ -34,7 +34,16 @@ static int show_console_dev(struct seq_file *m, void *v) if (con->device) { const struct tty_driver *driver; int index; + + /* + * Take console_lock to serialize device() callback with + * other console operations. For example, fg_console is + * modified under console_lock when switching vt. + */ + console_lock(); driver = con->device(con, &index); + console_unlock(); + if (driver) { dev = MKDEV(driver->major, driver->minor_start); dev += index; @@ -50,8 +59,8 @@ static int show_console_dev(struct seq_file *m, void *v) seq_printf(m, "%s%d", con->name, con->index); seq_pad(m, ' '); seq_printf(m, "%c%c%c (%s)", con->read ? 'R' : '-', - con->write ? 'W' : '-', con->unblank ? 'U' : '-', - flags); + ((con->flags & CON_NBCON) || con->write) ? 'W' : '-', + con->unblank ? 'U' : '-', flags); if (dev) seq_printf(m, " %4d:%d", MAJOR(dev), MINOR(dev)); @@ -60,11 +69,17 @@ static int show_console_dev(struct seq_file *m, void *v) } static void *c_start(struct seq_file *m, loff_t *pos) + __acquires(&console_mutex) { struct console *con; loff_t off = 0; - console_lock(); + /* + * Hold the console_list_lock to guarantee safe traversal of the + * console list. SRCU cannot be used because there is no + * place to store the SRCU cookie. + */ + console_list_lock(); for_each_console(con) if (off++ == *pos) break; @@ -75,13 +90,15 @@ static void *c_start(struct seq_file *m, loff_t *pos) static void *c_next(struct seq_file *m, void *v, loff_t *pos) { struct console *con = v; + ++*pos; - return con->next; + return hlist_entry_safe(con->node.next, struct console, node); } static void c_stop(struct seq_file *m, void *v) + __releases(&console_mutex) { - console_unlock(); + console_list_unlock(); } static const struct seq_operations consoles_op = { |