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 <vvs@virtuozzo.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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 <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20211220133250.3070-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20211126081611.11001-18-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20211126081611.11001-13-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 <marcel@holtmann.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Andreas Koensgen <ajk@comnets.uni-bremen.de>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> [NFC]
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20211122094529.24171-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Both do_SAK_work() and vc_SAK() provide a valid tty to __do_SAK(), so
remove the check.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20211118071911.12059-3-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20211118071911.12059-2-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 <jirislaby@kernel.org>
Signed-off-by: Nguyen Dinh Phi <phind.uet@gmail.com>
Link: https://lore.kernel.org/r/20210823000641.2082292-1-phind.uet@gmail.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
put_tty_driver() is an alias for tty_driver_kref_put(). There is no need
for two exported identical functions, therefore switch all users of
old put_tty_driver() to new tty_driver_kref_put() and remove the former
for good.
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Cc: Jens Taprogge <jens.taprogge@taprogge.org>
Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: Scott Branden <scott.branden@broadcom.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: David Lin <dtwlin@gmail.com>
Cc: Johan Hovold <johan@kernel.org>
Cc: Alex Elder <elder@kernel.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: David Sterba <dsterba@suse.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: Oliver Neukum <oneukum@suse.com>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Mathias Nyman <mathias.nyman@intel.com>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Acked-by: Alex Elder <elder@linaro.org>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Max Filippov <jcmvbkbc@gmail.com>
Acked-by: David Sterba <dsterba@suse.com>
Acked-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210723074317.32690-8-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since commit f34d7a5b70 (tty: The big operations rework) in 2008,
tty_set_operations() is a simple one-line assignment. There is no reason
for this to be an exported function, hence move it to a header and make
an inline from that.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210723074317.32690-7-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit f9e053dcfc (tty: Serialize tty flow control changes with
flow_lock) renamed start_tty to __start_tty and stop_tty to __stop_tty
and introduced new start_tty and stop_tty. But it left kernel-doc
comments on the old locations:
tty_io.c:785: warning: expecting prototype for stop_tty(). Prototype was for __stop_tty() instead
tty_io.c:816: warning: expecting prototype for start_tty(). Prototype was for __start_tty() instead
Fix that by moving the comments to appropriate locations.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210519072153.3859-4-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
After commits a9cbbb80e3 (tty: avoid using vfs_iocb_iter_write() for
redirected console writes) and dd78b0c483 (tty: implement read_iter),
the tty_read and tty_write kernel-doc comments don't match the code:
tty_io.c:931: warning: Function parameter or member 'iocb' not described in 'tty_read'
tty_io.c:931: warning: Function parameter or member 'to' not described in 'tty_read'
tty_io.c:931: warning: Excess function parameter 'file' description in 'tty_read'
tty_io.c:931: warning: Excess function parameter 'buf' description in 'tty_read'
tty_io.c:931: warning: Excess function parameter 'count' description in 'tty_read'
tty_io.c:931: warning: Excess function parameter 'ppos' description in 'tty_read'
tty_io.c:1115: warning: Function parameter or member 'iocb' not described in 'file_tty_write'
tty_io.c:1115: warning: Function parameter or member 'from' not described in 'file_tty_write'
tty_io.c:1115: warning: expecting prototype for tty_write(). Prototype was for file_tty_write() instead
Fix them to correspond the reality, i.e. the switch from read/write to
read_iter/write_iter.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210519072153.3859-3-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Delete a blank line before EXPORT_SYMBOL(foo) so that EXPORT_SYMBOL(foo)
immediately follow its function/variable, reported by checkpatch.pl.
Signed-off-by: Xiaofei Tan <tanxiaofei@huawei.com>
Link: https://lore.kernel.org/r/1620811585-18582-14-git-send-email-tanxiaofei@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Group the ctrl members under a single struct called ctrl. The new struct
contains 'pgrp', 'session', 'pktstatus', and 'packet'. 'pktstatus' and
'packet' used to be bits in a bitfield. The struct also contains the
lock protecting them to share the same cache line.
Note that commit c545b66c69 (tty: Serialize tcflow() with other tty
flow control changes) added a padding to the original bitfield. It was
for the bitfield to occupy a whole 64b word to avoid interferring stores
on Alpha (cannot we evaporate this arch with weird implications to C
code yet?). But it doesn't work as expected as the padding
(tty_struct::ctrl_unused) is aligned to a 8B boundary too and occupies
some bytes from the next word.
So make it reliable by:
1) setting __aligned of the struct -- that aligns the start, and
2) making 'unsigned long unused[0]' as the last member of the struct --
pads the end.
Add a kerneldoc comment for this grouped members.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org
Link: https://lore.kernel.org/r/20210505091928.22010-14-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Group the flow flags under a single struct called flow. The new struct
contains 'stopped' and 'tco_stopped' bools which used to be bits in a
bitfield. The struct also contains the lock protecting them to
potentially share the same cache line.
Note that commit c545b66c69 (tty: Serialize tcflow() with other tty
flow control changes) added a padding to the original bitfield. It was
for the bitfield to occupy a whole 64b word to avoid interferring stores
on Alpha (cannot we evaporate this arch with weird implications to C
code yet?). But it doesn't work as expected as the padding
(tty_struct::unused) is aligned to a 8B boundary too and occupies some
bytes from the next word.
So make it reliable by:
1) setting __aligned of the struct -- that aligns the start, and
2) making 'unsigned long unused[0]' as the last member of the struct --
pads the end.
This is also the perfect time to start the documentation of tty_struct
where all this lives. So we start by documenting what these bools
actually serve for. And why we do all the alignment dances. Only the few
up-to-date information from the Theodore's comment made it into this new
Kerneldoc comment.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: "Maciej W. Rozycki" <macro@orcam.me.uk>
Link: https://lore.kernel.org/r/20210505091928.22010-13-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There are a number of functions and #defines in include/linux/tty.h that
do not belong there as they are private to the tty core code.
Create an initial drivers/tty/tty.h file and copy the odd "tty logging"
macros into it to seed the file with some initial things that we know
nothing outside of the tty core should be calling.
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20210408125134.3016837-2-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Factor out the deprecated serial flags handling and tty-operation check
shared with the compat TIOCSSERIAL handler.
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210407095208.31838-6-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Use pr_warn_ratelimited() when warning about deprecated serial flags
instead of open coding.
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210407095208.31838-5-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Drivers should return -ENOTTY ("Inappropriate I/O control operation")
when an ioctl isn't supported, while -EINVAL is used for invalid
arguments.
Fix up the TIOCMGET, TIOCMSET and TIOCGICOUNT helpers which returned
-EINVAL when a tty driver did not implement the corresponding
operations.
Note that the TIOCMGET and TIOCMSET helpers predate git and do not get a
corresponding Fixes tag below.
Fixes: d281da7ff6 ("tty: Make tiocgicount a handler")
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210407095208.31838-3-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Resolves a merge issue with:
drivers/tty/hvc/hvcs.c
and we want the tty/serial fixes from 5.12-rc3 in here as well.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ptychar was not const, so mark it as such. And move this variable to the
only place where it's used.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210302062214.29627-36-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Now that noone checks the return value, switch the return type of
tty_unregister_driver to void. We can do that as we always return zero.
Generally, drivers are not allowed to call tty_unregister_driver while
there are open devices.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210302062214.29627-35-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 33d4ae9885.
Pierre-Louis writes:
Our SOF/audio CI shows an across-the-board regression when we try v5.12-rc1,
specifically on pause/resume tests with an interactive terminal running 'aplay
-i' commands managed by expect to simulate the user pressing the space bar to
pause/unpause. It turns out the processes are not longer killed and the audio
devices remain busy (see publicly available test results listed below).
git bisect points to commit 33d4ae9885 ("drivers:tty:pty: Fix a race
causing data loss on close"). Reverting the patch fixes the issue on all test
devices.
Further analysis with Corey Minyard points to a problem where a slave tty will
not get a SIGHUP when the master is closed.
So revert this for now:
Reported-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/00154592-c5ee-aaba-956e-b265473b53bc@linux.intel.com
Cc: Corey Minyard <cminyard@mvista.com>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Mark Brown <broonie@kernel.org>,
Fixes: 33d4ae9885 ("drivers:tty:pty: Fix a race causing data loss on close")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Here is the big set of tty/serial driver changes for 5.12-rc1.
Nothing huge, just lots of good cleanups and additions:
- Your n_tty line discipline cleanups
- vt core cleanups and reworks to make the code more "modern"
- stm32 driver additions
- tty led support added to the tty core and led layer
- minor serial driver fixups and additions
All of these have been in linux-next for a while with no reported
issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-5.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty/serial driver updates from Greg KH:
"Here is the big set of tty/serial driver changes for 5.12-rc1.
Nothing huge, just lots of good cleanups and additions:
- n_tty line discipline cleanups
- vt core cleanups and reworks to make the code more "modern"
- stm32 driver additions
- tty led support added to the tty core and led layer
- minor serial driver fixups and additions
All of these have been in linux-next for a while with no reported
issues"
* tag 'tty-5.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (54 commits)
serial: core: Remove BUG_ON(in_interrupt()) check
vt_ioctl: Remove in_interrupt() check
dt-bindings: serial: imx: Switch to my personal address
vt: keyboard, use new API for keyboard_tasklet
serial: stm32: improve platform_get_irq condition handling in init_port
serial: ifx6x60: Remove driver for deprecated platform
tty: fix up iterate_tty_read() EOVERFLOW handling
tty: fix up hung_up_tty_read() conversion
tty: fix up hung_up_tty_write() conversion
tty: teach the n_tty ICANON case about the new "cookie continuations" too
tty: teach n_tty line discipline about the new "cookie continuations"
tty: clean up legacy leftovers from n_tty line discipline
tty: implement read_iter
tty: convert tty_ldisc_ops 'read()' function to take a kernel pointer
serial: remove sirf prima/atlas driver
serial: mxs-auart: Remove <asm/cacheflush.h>
serial: mxs-auart: Remove serial_mxs_probe_dt()
serial: fsl_lpuart: Use of_device_get_match_data()
dt-bindings: serial: renesas,hscif: Add r8a779a0 support
tty: serial: Drop unused efm32 serial driver
...
Al root-caused a new warning from syzbot to the ttyprintk tty driver
returning a write count larger than the data the tty layer actually gave
it. Which confused the tty write code mightily, and with the new
iov_iter based code, caused a WARNING in iov_iter_revert().
syzbot correctly bisected the source of the new warning to commit
9bb48c82ac ("tty: implement write_iter"), but the oddity goes back
much further, it just didn't get caught by anything before.
Reported-by: syzbot+3d2c27c2b7dc2a94814d@syzkaller.appspotmail.com
Fixes: 9bb48c82ac ("tty: implement write_iter")
Debugged-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It turns out that the vfs_iocb_iter_{read,write}() functions are
entirely broken, and don't actually use the passed-in file pointer for
IO - only for the preparatory work (permission checking and for the
write_iter function lookup).
That worked fine for overlayfs, which always builds the new iocb with
the same file pointer that it passes in, but in the general case it ends
up doing nonsensical things (and could cause an iterator call that
doesn't even match the passed-in file pointer).
This subtly broke the tty conversion to write_iter in commit
9bb48c82ac ("tty: implement write_iter"), because the console
redirection didn't actually end up redirecting anything, since the
passed-in file pointer was basically ignored, and the actual write was
done with the original non-redirected console tty after all.
The main visible effect of this is that the console messages were no
longer logged to /var/log/boot.log during graphical boot.
Fix the issue by simply not using the vfs write "helper" function at
all, and just redirecting the write entirely internally to the tty
layer. Do the target writability permission checks when actually
registering the target tty with TIOCCONS instead of at write time.
Fixes: 9bb48c82ac ("tty: implement write_iter")
Reported-and-tested-by: Hans de Goede <hdegoede@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
layer to use write_iter. Fix the redirected_tty_write declaration
also in n_tty and change the comparisons to use write_iter instead of
write.
[ Also moved the declaration of redirected_tty_write() to the proper
location in a header file. The reason for the bug was the bogus extern
declaration in n_tty.c silently not matching the changed definition in
tty_io.c, and because it wasn't in a shared header file, there was no
cross-checking of the declaration.
Sami noticed because Clang's Control Flow Integrity checking ended up
incidentally noticing the inconsistent declaration. - Linus ]
Fixes: 9bb48c82ac ("tty: implement write_iter")
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In commit "tty: implement write_iter", I left the write_iter conversion
of the hung up tty case alone, because I incorrectly thought it didn't
matter.
Jiri showed me the errors of my ways, and pointed out the problems with
that incomplete conversion. Fix it all up.
Reported-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/CAHk-=wh+-rGsa=xruEWdg_fJViFG8rN9bpLrfLz=_yBYh2tBhA@mail.gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When I converted the tty_ldisc_ops 'read()' function to take a kernel
pointer, I was a bit too aggressive about the ldisc returning EOVERFLOW.
Yes, we want to have EOVERFLOW override any partially read data (because
the whole point is that the buffer was too small for the whole packet,
and we don't want to see partial packets), but it shouldn't override a
previous EFAULT.
And in fact, it really is just EOVERFLOW that is special and should
throw away any partially read data, not "any error". Admittedly
EOVERFLOW is currently the only one that can happen for a continuation
read - and if the first read iteration returns an error we won't have this issue.
So this is more of a technicality, but let's just make the intent very
explicit, and re-organize the error handling a bit so that this is all
clearer.
Reported-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/CAHk-=wh+-rGsa=xruEWdg_fJViFG8rN9bpLrfLz=_yBYh2tBhA@mail.gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In commit "tty: implement read_iter", I left the read_iter conversion of
the hung up tty case alone, because I incorrectly thought it didn't
matter.
Jiri showed me the errors of my ways, and pointed out the problems with
that incomplete conversion. Fix it all up.
Reported-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/CAHk-=wh+-rGsa=xruEWdg_fJViFG8rN9bpLrfLz=_yBYh2tBhA@mail.gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In commit "tty: implement write_iter", I left the write_iter conversion
of the hung up tty case alone, because I incorrectly thought it didn't
matter.
Jiri showed me the errors of my ways, and pointed out the problems with
that incomplete conversion. Fix it all up.
Reported-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/CAHk-=wh+-rGsa=xruEWdg_fJViFG8rN9bpLrfLz=_yBYh2tBhA@mail.gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fixes both the "splice/sendfile to a tty" and "splice/sendfile from a
tty" regression from 5.10.
* 'tty-splice' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux:
tty: teach the n_tty ICANON case about the new "cookie continuations" too
tty: teach n_tty line discipline about the new "cookie continuations"
tty: clean up legacy leftovers from n_tty line discipline
tty: implement read_iter
tty: convert tty_ldisc_ops 'read()' function to take a kernel pointer
tty: implement write_iter
We want the single "splice/sendfile to a tty" regression fix into
tty-linus so it can get into 5.11-final, while the larger patch series
fixing "splice/sendfile from a tty" should wait for 5.12-rc1 so that we
get more testing.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This makes the tty layer use the .write_iter() function instead of the
traditional .write() functionality.
That allows writev(), but more importantly also makes it possible to
enable .splice_write() for ttys, reinstating the "splice to tty"
functionality that was lost in commit 36e2c7421f ("fs: don't allow
splice read/write without explicit ops").
Fixes: 36e2c7421f ("fs: don't allow splice read/write without explicit ops")
Reported-by: Oliver Giles <ohw.giles@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that the ldisc read() function takes kernel pointers, it's fairly
straightforward to make the tty file operations use .read_iter() instead
of .read().
That automatically gives us vread() and friends, and also makes it
possible to do .splice_read() on ttys again.
Fixes: 36e2c7421f ("fs: don't allow splice read/write without explicit ops")
Reported-by: Oliver Giles <ohw.giles@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The tty line discipline .read() function was passed the final user
pointer destination as an argument, which doesn't match the 'write()'
function, and makes it very inconvenient to do a splice method for
ttys.
This is a conversion to use a kernel buffer instead.
NOTE! It does this by passing the tty line discipline ->read() function
an additional "cookie" to fill in, and an offset into the cookie data.
The line discipline can fill in the cookie data with its own private
information, and then the reader will repeat the read until either the
cookie is cleared or it runs out of data.
The only real user of this is N_HDLC, which can use this to handle big
packets, even if the kernel buffer is smaller than the whole packet.
Cc: Christoph Hellwig <hch@lst.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove the tty_vhangup() from the pty code and just release the
redirect. The tty_vhangup() results in data loss and data out of order
issues.
If you write to a pty master an immediately close the pty master, the
receiver might get a chunk of data dropped, but then receive some later
data. That's obviously something rather unexpected for a user. It
certainly confused my test program.
It turns out that tty_vhangup() on the slave pty gets called from
pty_close(), and that causes the data on the slave side to be flushed,
but due to races more data can be copied into the slave side's buffer
after that. Consider the following sequence:
thread1 thread2 thread3
------- ------- -------
| |-write data into buffer,
| | n_tty buffer is filled
| | along with other buffers
| |-pty_close(master)
| |--tty_vhangup(slave)
| |---tty_ldisc_hangup()
| |----n_tty_flush_buffer()
| |-----reset_buffer_flags()
|-n_tty_read() |
|--up_read(&tty->termios_rwsem);
| |------down_read(&tty->termios_rwsem)
| |------clear n_tty buffer contents
| |------up_read(&tty->termios_rwsem)
|--tty_buffer_flush_work() |
|--schedules work calling |
| flush_to_ldisc() |
| |-flush_to_ldisc()
| |--receive_buf()
| |---tty_port_default_receive_buf()
| |----tty_ldisc_receive_buf()
| |-----n_tty_receive_buf2()
| |------n_tty_receive_buf_common()
| |-------down_read(&tty->termios_rwsem)
| |-------__receive_buf()
| | copies data into n_tty buffer
| |-------up_read(&tty->termios_rwsem)
|--down_read(&tty->termios_rwsem)
|--copy buffer data to user
>From this sequence, you can see that thread2 writes to the buffer then
only clears the part of the buffer in n_tty. The n_tty receive buffer
code then copies more data into the n_tty buffer.
But part of the vhangup, releasing the redirect, is still required to
avoid issues with consoles running on pty slaves. So do that.
As far as I can tell, that is all that should be required.
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Link: https://lore.kernel.org/r/20201124004902.1398477-3-minyard@acm.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This will be required by the pty code when it removes tty_vhangup() on
master close.
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Link: https://lore.kernel.org/r/20201124004902.1398477-2-minyard@acm.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
