From 23308ba54dcdb54481163bfb07dd8aeca76a7a2e Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Thu, 4 Nov 2010 16:20:24 +0100 Subject: [PATCH] console: add /proc/consoles It allows users to see what consoles are currently known to the system and with what flags. It is based on Werner's patch, the part about traversing fds was removed, the code was moved to kernel/printk.c, where consoles are handled and it makes more sense to me. Signed-off-by: Jiri Slaby [cleanups] Signed-off-by: "Dr. Werner Fink" Cc: Al Viro Cc: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman --- Documentation/filesystems/proc.txt | 24 ++++++ fs/proc/Makefile | 1 + fs/proc/proc_console.c | 114 +++++++++++++++++++++++++++++ 3 files changed, 139 insertions(+) create mode 100644 fs/proc/proc_console.c diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index e73df2722ff3..9471225212c4 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -1181,6 +1181,30 @@ Table 1-12: Files in /proc/fs/ext4/ mb_groups details of multiblock allocator buddy cache of free blocks .............................................................................. +2.0 /proc/consoles +------------------ +Shows registered system console lines. + +To see which character device lines are currently used for the system console +/dev/console, you may simply look into the file /proc/consoles: + + > cat /proc/consoles + tty0 -WU (ECp) 4:7 + ttyS0 -W- (Ep) 4:64 + +The columns are: + + device name of the device + operations R = can do read operations + W = can do write operations + U = can do unblank + flags E = it is enabled + C = it is prefered console + B = it is primary boot console + p = it is used for printk buffer + b = it is not a TTY but a Braille device + a = it is safe to use when cpu is offline + major:minor major and minor number of the device separated by a colon ------------------------------------------------------------------------------ Summary diff --git a/fs/proc/Makefile b/fs/proc/Makefile index 2758e2afc518..288a49e098bf 100644 --- a/fs/proc/Makefile +++ b/fs/proc/Makefile @@ -15,6 +15,7 @@ proc-y += devices.o proc-y += interrupts.o proc-y += loadavg.o proc-y += meminfo.o +proc-y += proc_console.o proc-y += stat.o proc-y += uptime.o proc-y += version.o diff --git a/fs/proc/proc_console.c b/fs/proc/proc_console.c new file mode 100644 index 000000000000..8a707609f528 --- /dev/null +++ b/fs/proc/proc_console.c @@ -0,0 +1,114 @@ +/* + * Copyright (c) 2010 Werner Fink, Jiri Slaby + * + * Licensed under GPLv2 + */ + +#include +#include +#include +#include +#include + +/* + * This is handler for /proc/consoles + */ +static int show_console_dev(struct seq_file *m, void *v) +{ + static const struct { + short flag; + char name; + } con_flags[] = { + { CON_ENABLED, 'E' }, + { CON_CONSDEV, 'C' }, + { CON_BOOT, 'B' }, + { CON_PRINTBUFFER, 'p' }, + { CON_BRL, 'b' }, + { CON_ANYTIME, 'a' }, + }; + char flags[ARRAY_SIZE(con_flags) + 1]; + struct console *con = v; + unsigned int a; + int len; + dev_t dev = 0; + + if (con->device) { + const struct tty_driver *driver; + int index; + driver = con->device(con, &index); + if (driver) { + dev = MKDEV(driver->major, driver->minor_start); + dev += index; + } + } + + for (a = 0; a < ARRAY_SIZE(con_flags); a++) + flags[a] = (con->flags & con_flags[a].flag) ? + con_flags[a].name : ' '; + flags[a] = 0; + + seq_printf(m, "%s%d%n", con->name, con->index, &len); + len = 21 - len; + if (len < 1) + len = 1; + seq_printf(m, "%*c%c%c%c (%s)", len, ' ', con->read ? 'R' : '-', + con->write ? 'W' : '-', con->unblank ? 'U' : '-', + flags); + if (dev) + seq_printf(m, " %4d:%d", MAJOR(dev), MINOR(dev)); + + seq_printf(m, "\n"); + + return 0; +} + +static void *c_start(struct seq_file *m, loff_t *pos) +{ + struct console *con; + loff_t off = 0; + + acquire_console_sem(); + for_each_console(con) + if (off++ == *pos) + break; + + return con; +} + +static void *c_next(struct seq_file *m, void *v, loff_t *pos) +{ + struct console *con = v; + ++*pos; + return con->next; +} + +static void c_stop(struct seq_file *m, void *v) +{ + release_console_sem(); +} + +static const struct seq_operations consoles_op = { + .start = c_start, + .next = c_next, + .stop = c_stop, + .show = show_console_dev +}; + +static int consoles_open(struct inode *inode, struct file *file) +{ + return seq_open(file, &consoles_op); +} + +static const struct file_operations proc_consoles_operations = { + .open = consoles_open, + .read = seq_read, + .llseek = seq_lseek, + .release = seq_release, +}; + +static int register_proc_consoles(void) +{ + proc_create("consoles", 0, NULL, &proc_consoles_operations); + return 0; +} +module_init(register_proc_consoles);