kernel/linux.git/drivers/tty/tty_io.c, branch v5.19

memcg: enable accounting for tty-related objects

2022-03-22T22:57:04+00:00

At each login the user forces the kernel to create a new terminal and allocate up to ~1Kb memory for the tty-related structures. By default it's allowed to create up to 4096 ptys with 1024 reserve for initial mount namespace only and the settings are controlled by host admin. Though this default is not enough for hosters with thousands of containers per node. Host admin can be forced to increase it up to NR_UNIX98_PTY_MAX = 1<<20. By default container is restricted by pty mount_opt.max = 1024, but admin inside container can change it via remount. As a result, one container can consume almost all allowed ptys and allocate up to 1Gb of unaccounted memory. It is not enough per-se to trigger OOM on host, however anyway, it allows to significantly exceed the assigned memcg limit and leads to troubles on the over-committed node. It makes sense to account for them to restrict the host's memory consumption from inside the memcg-limited container. Link: https://lkml.kernel.org/r/5d4bca06-7d4f-a905-e518-12981ebca1b3@virtuozzo.com Signed-off-by: Vasily Averin Cc: Michal Hocko Cc: Shakeel Butt Cc: Johannes Weiner Cc: Vladimir Davydov Cc: Roman Gushchin Cc: Greg Kroah-Hartman Cc: Jiri Slaby Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

tty: tty_io: Switch to vmalloc() fallback in case of TTY_NO_WRITE_SPLIT

2021-12-21T08:18:44+00:00

When TTY_NO_WRITE_SPLIT is set and 64 KiB chunks are used, allow vmalloc() fallback. Supply __GFP_RETRY_MAYFAIL to make kmalloc() preferable over vmalloc() since we may want a better performance. Note, both current users copy data to another buffer anyway, so the type of our allocation doesn't affect their expectations. Signed-off-by: Andy Shevchenko Link: https://lore.kernel.org/r/20211220133250.3070-1-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman

tty: add kernel-doc for tty_standard_install

2021-11-26T15:27:43+00:00

It is the only missing exported function which is not documented. Fix it. Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20211126081611.11001-23-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

tty: add kernel-doc for more tty_driver functions

2021-11-26T15:27:43+00:00

The only documented function for tty_driver structure allocation/registration was __tty_alloc_driver(). Fix highlighting in that comment. And add kernel-doc headers to all tty_driver_kref_put(), tty_register_driver(), and tty_unregister_driver() -- i.e. the main ones. More to follow later. Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20211126081611.11001-18-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

tty: reformat kernel-doc in tty_io.c

2021-11-26T15:27:43+00:00

Kernel-doc is a bit strict about some formatting. So fix these: 1) When there is a tab in comments, it thinks the line is a continuation one. So the description of the functions end up as descriptions of the last parameter described. Remove the tabs. 2) Remove newlines before parameters description and after the comments. This was not wrong per se, only inconsistent with the rest of the file. 3) Add periods to the end of sentences where appropriate. 4) Add "()" to function names and "%" to constants, so that they are properly highlighted. By the above, this patch also unifies these docs with the other kernel-doc's in this file. Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20211126081611.11001-13-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

tty: remove file from tty_ldisc_ops::ioctl and compat_ioctl

2021-11-25T17:36:27+00:00

After the previous patches, noone needs 'file' parameter in neither ioctl hook from tty_ldisc_ops. So remove 'file' from both of them. Cc: Marcel Holtmann Cc: Johan Hedberg Cc: Luiz Augusto von Dentz Cc: Wolfgang Grandegger Cc: Marc Kleine-Budde Cc: "David S. Miller" Cc: Jakub Kicinski Cc: Andreas Koensgen Cc: Paul Mackerras Acked-by: Krzysztof Kozlowski [NFC] Acked-by: Dmitry Torokhov Acked-by: Marc Kleine-Budde Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20211122094529.24171-1-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

tty: clean up whitespace in __do_SAK()

2021-11-25T17:31:32+00:00

Remove spaces before the 'i' variable declaration and wrap parameters of group_send_sig_info(). Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20211118071911.12059-4-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

tty: remove tty NULL check from __do_SAK()

2021-11-25T17:31:32+00:00

Both do_SAK_work() and vc_SAK() provide a valid tty to __do_SAK(), so remove the check. Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20211118071911.12059-3-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

tty: remove TTY_SOFT_SAK part from __do_SAK()

2021-11-25T17:31:32+00:00

Remove the TTY_SOFT_SAK part. It is never defined, so this is only confusing. It was actually never defined since its introduction in 0.99.14g. Signed-off-by: Jiri Slaby Link: https://lore.kernel.org/r/20211118071911.12059-2-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman

tty: Fix data race between tiocsti() and flush_to_ldisc()

2021-08-26T12:51:38+00:00

The ops->receive_buf() may be accessed concurrently from these two functions. If the driver flushes data to the line discipline receive_buf() method while tiocsti() is waiting for the ops->receive_buf() to finish its work, the data race will happen. For example: tty_ioctl |tty_ldisc_receive_buf ->tioctsi | ->tty_port_default_receive_buf | ->tty_ldisc_receive_buf ->hci_uart_tty_receive | ->hci_uart_tty_receive ->h4_recv | ->h4_recv In this case, the h4 receive buffer will be overwritten by the latecomer, and we will lost the data. Hence, change tioctsi() function to use the exclusive lock interface from tty_buffer to avoid the data race. Reported-by: syzbot+97388eb9d31b997fe1d0@syzkaller.appspotmail.com Reviewed-by: Jiri Slaby Signed-off-by: Nguyen Dinh Phi Link: https://lore.kernel.org/r/20210823000641.2082292-1-phind.uet@gmail.com Cc: stable Signed-off-by: Greg Kroah-Hartman