From 6c2754c28f2388a276fe21edde826f2113c8f60e Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 23 Oct 2010 08:14:12 -0700 Subject: Revert "tty: Add a new file /proc/tty/consoles" This reverts commit f4a3e0bceb57466c31757f25e4e0ed108d1299ec. Jiri Sladby points out that the tty structure we're using may already be gone, and Al Viro doesn't hold back in complaining about the random loading of 'filp->private_data' which doesn't have to be a pointer at all, nor does checking the magic field for TTY_MAGIC prove anything. Belated review by Al: "a) global variable depending on stdin of the last opener? Affecting output of read(2)? Really? b) iterator is broken; list should be locked in ->start(), unlocked in ->stop() and *NOT* unlocked/relocked in ->next() c) ->show() ought to do nothing in case of ->device == NULL, instead of skipping those in ->next()/->start() d) regardless of the merits of the bright idea about asterisk at that line in output *and* regardless of (a), the implementation is not only atrociously ugly, it's actually very likely to be a roothole. Verifying that Cthulhu knows what number happens to be address of a tty_struct by blindly dereferencing memory at that address... Ouch. Please revert that crap." And Christoph pipes in and NAK's the approach of walking fd tables etc too. So it's pretty unanimous. Noticed-by: Jri Slaby Requested-by: Al Viro Cc: Greg Kroah-Hartman Cc: Werner Fink Cc: Alan Cox Cc: Christoph Hellwig Signed-off-by: Linus Torvalds --- Documentation/filesystems/proc.txt | 32 -------------------------------- 1 file changed, 32 deletions(-) (limited to 'Documentation') diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 98223a67694..a6aca874088 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -1075,7 +1075,6 @@ Table 1-11: Files in /proc/tty drivers list of drivers and their usage ldiscs registered line disciplines driver/serial usage statistic and status of single tty lines - consoles registered system console lines .............................................................................. To see which tty's are currently in use, you can simply look into the file @@ -1094,37 +1093,6 @@ To see which tty's are currently in use, you can simply look into the file /dev/tty /dev/tty 5 0 system:/dev/tty unknown /dev/tty 4 1-63 console -To see which character device lines are currently used for the system console -/dev/console, you may simply look into the file /proc/tty/consoles: - - > cat /proc/tty/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 - * = it is standard input of the reading process - major:minor major and minor number of the device separated by a colon - -If the reading process holds /dev/console open at the regular standard input -stream the active device will be marked by an asterisk: - - > cat /proc/tty/consoles < /dev/console - tty0 -WU (ECp*) 4:7 - ttyS0 -W- (Ep) 4:64 - > tty - /dev/pts/3 - 1.8 Miscellaneous kernel statistics in /proc/stat ------------------------------------------------- -- cgit v1.2.3-70-g09d2