linux.git/drivers/tty/serial/serial_core.c, branch v5.12 Linux kernel source tree serial: core: Remove BUG_ON(in_interrupt()) check 2021-02-09T10:45:04+00:00 Ahmed S. Darwish a.darwish@linutronix.de 2021-02-08T18:16:15+00:00 a157270fbf37f822e1fa9e9faa8ed8c81da1eb28 The usage of in_interrupt() in drivers is phased out for various reasons. In both exported functions where BUG_ON(in_interrupt()) is invoked, there is a mutex_lock() afterwards. mutex_lock() contains a might_sleep() which will already trigger a stack trace if the target functions is called from atomic context. Remove the BUG_ON() and add a "Context: " in the kernel-doc instead. Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Link: https://lore.kernel.org/r/20210208181615.381861-3-bigeasy@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
The usage of in_interrupt() in drivers is phased out for various
reasons.

In both exported functions where BUG_ON(in_interrupt()) is invoked,
there is a mutex_lock() afterwards. mutex_lock() contains a
might_sleep() which will already trigger a stack trace if the target
functions is called from atomic context.

Remove the BUG_ON() and add a "Context: " in the kernel-doc instead.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20210208181615.381861-3-bigeasy@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty_port: drop last traces of low_latency 2021-01-07T15:17:32+00:00 Jiri Slaby jslaby@suse.cz 2021-01-05T12:02:38+00:00 0bc1bd092af3c7c0b025ece93c3a86916f89f3ca The main purpose of tty_port::low_latency was removed in commit a9c3f68f3cd8 (tty: Fix low_latency BUG) back in 2014. It was left in place for drivers as an optional tune knob. But only one driver has been using it until the previous commit. So remove this misconcept completely, given there are no users. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20210105120239.28031-11-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
The main purpose of tty_port::low_latency was removed in commit
a9c3f68f3cd8 (tty: Fix low_latency BUG) back in 2014. It was left in
place for drivers as an optional tune knob. But only one driver has been
using it until the previous commit. So remove this misconcept
completely, given there are no users.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210105120239.28031-11-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial_core: Check for port state when tty is in error state 2020-12-09T14:34:37+00:00 Alexey Kardashevskiy aik@ozlabs.ru 2020-12-03T05:58:34+00:00 2f70e49ed860020f5abae4f7015018ebc10e1f0e At the moment opening a serial device node (such as /dev/ttyS3) succeeds even if there is no actual serial device behind it. Reading/writing/ioctls fail as expected because the uart port is not initialized (the type is PORT_UNKNOWN) and the TTY_IO_ERROR error state bit is set fot the tty. However setting line discipline does not have these checks 8250_port.c (8250 is the default choice made by univ8250_console_init()). As the result of PORT_UNKNOWN, uart_port::iobase is NULL which a platform translates onto some address accessing which produces a crash like below. This adds tty_port_initialized() to uart_set_ldisc() to prevent the crash. Found by syzkaller. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Link: https://lore.kernel.org/r/20201203055834.45838-1-aik@ozlabs.ru Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
At the moment opening a serial device node (such as /dev/ttyS3)
succeeds even if there is no actual serial device behind it.
Reading/writing/ioctls fail as expected because the uart port is not
initialized (the type is PORT_UNKNOWN) and the TTY_IO_ERROR error state
bit is set fot the tty.

However setting line discipline does not have these checks
8250_port.c (8250 is the default choice made by univ8250_console_init()).
As the result of PORT_UNKNOWN, uart_port::iobase is NULL which
a platform translates onto some address accessing which produces a crash
like below.

This adds tty_port_initialized() to uart_set_ldisc() to prevent the crash.

Found by syzkaller.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Link: https://lore.kernel.org/r/20201203055834.45838-1-aik@ozlabs.ru
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Merge 5.9.0-rc6 into tty-next 2020-09-21T07:23:55+00:00 Greg Kroah-Hartman gregkh@linuxfoundation.org 2020-09-21T07:23:55+00:00 33f16b25a091687388152d4b29593a39d819aa22 We need the tty/serial fixes in here and this resolves a merge issue in the 8250 driver. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
We need the tty/serial fixes in here and this resolves a merge issue in
the 8250 driver.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: core: fix console port-lock regression 2020-09-16T11:22:44+00:00 Johan Hovold johan@kernel.org 2020-09-09T14:31:01+00:00 e0830dbf71f191851ed3772d2760f007b7c5bc3a Fix the port-lock initialisation regression introduced by commit a3cb39d258ef ("serial: core: Allow detach and attach serial device for console") by making sure that the lock is again initialised during console setup. The console may be registered before the serial controller has been probed in which case the port lock needs to be initialised during console setup by a call to uart_set_options(). The console-detach changes introduced a regression in several drivers by effectively removing that initialisation by not initialising the lock when the port is used as a console (which is always the case during console setup). Add back the early lock initialisation and instead use a new console-reinit flag to handle the case where a console is being re-attached through sysfs. The question whether the console-detach interface should have been added in the first place is left for another discussion. Note that the console-enabled check in uart_set_options() is not redundant because of kgdboc, which can end up reinitialising an already enabled console (see commit 42b6a1baa3ec ("serial_core: Don't re-initialize a previously initialized spinlock.")). Fixes: a3cb39d258ef ("serial: core: Allow detach and attach serial device for console") Cc: stable <stable@vger.kernel.org> # 5.7 Signed-off-by: Johan Hovold <johan@kernel.org> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20200909143101.15389-3-johan@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Fix the port-lock initialisation regression introduced by commit
a3cb39d258ef ("serial: core: Allow detach and attach serial device for
console") by making sure that the lock is again initialised during
console setup.

The console may be registered before the serial controller has been
probed in which case the port lock needs to be initialised during
console setup by a call to uart_set_options(). The console-detach
changes introduced a regression in several drivers by effectively
removing that initialisation by not initialising the lock when the port
is used as a console (which is always the case during console setup).

Add back the early lock initialisation and instead use a new
console-reinit flag to handle the case where a console is being
re-attached through sysfs.

The question whether the console-detach interface should have been added
in the first place is left for another discussion.

Note that the console-enabled check in uart_set_options() is not
redundant because of kgdboc, which can end up reinitialising an already
enabled console (see commit 42b6a1baa3ec ("serial_core: Don't
re-initialize a previously initialized spinlock.")).

Fixes: a3cb39d258ef ("serial: core: Allow detach and attach serial device for console")
Cc: stable <stable@vger.kernel.org>     # 5.7
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200909143101.15389-3-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: core: fix port-lock initialisation 2020-09-16T11:22:10+00:00 Johan Hovold johan@kernel.org 2020-09-09T14:31:00+00:00 fe88c6489264eaea23570dfdf03e1d3f5f47f423 Commit f743061a85f5 ("serial: core: Initialise spin lock before use in uart_configure_port()") tried to work around a breakage introduced by commit a3cb39d258ef ("serial: core: Allow detach and attach serial device for console") by adding a second initialisation of the port lock when registering the port. As reported by the build robots [1], this doesn't really solve the regression introduced by the console-detach changes and also adds a second redundant initialisation of the lock for normal ports. Start cleaning up this mess by removing the redundant initialisation and making sure that the port lock is again initialised once-only for ports that aren't already in use as a console. [1] https://lore.kernel.org/r/20200802054852.GR23458@shao2-debian Fixes: f743061a85f5 ("serial: core: Initialise spin lock before use in uart_configure_port()") Fixes: a3cb39d258ef ("serial: core: Allow detach and attach serial device for console") Cc: stable <stable@vger.kernel.org> # 5.7 Signed-off-by: Johan Hovold <johan@kernel.org> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20200909143101.15389-2-johan@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Commit f743061a85f5 ("serial: core: Initialise spin lock before use in
uart_configure_port()") tried to work around a breakage introduced by
commit a3cb39d258ef ("serial: core: Allow detach and attach serial
device for console") by adding a second initialisation of the port lock
when registering the port.

As reported by the build robots [1], this doesn't really solve the
regression introduced by the console-detach changes and also adds a
second redundant initialisation of the lock for normal ports.

Start cleaning up this mess by removing the redundant initialisation and
making sure that the port lock is again initialised once-only for ports
that aren't already in use as a console.

[1] https://lore.kernel.org/r/20200802054852.GR23458@shao2-debian

Fixes: f743061a85f5 ("serial: core: Initialise spin lock before use in uart_configure_port()")
Fixes: a3cb39d258ef ("serial: core: Allow detach and attach serial device for console")
Cc: stable <stable@vger.kernel.org>     # 5.7
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200909143101.15389-2-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: core: Simplify with dev_err_probe() 2020-09-04T15:14:31+00:00 Krzysztof Kozlowski krzk@kernel.org 2020-09-01T15:31:00+00:00 89c65d664832ebaf2cbdcfe83b25c0036780feb7 Common pattern of handling deferred probe can be simplified with dev_err_probe(). Less code and the error value gets printed. Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org> Reviewed-by: Lukas Wunner <lukas@wunner.de> Link: https://lore.kernel.org/r/20200901153100.18827-2-krzk@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Common pattern of handling deferred probe can be simplified with
dev_err_probe().  Less code and the error value gets printed.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/20200901153100.18827-2-krzk@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Merge 5.9-rc3 into tty-next 2020-08-31T05:19:25+00:00 Greg Kroah-Hartman gregkh@linuxfoundation.org 2020-08-31T05:19:25+00:00 8f49a2fe8e6bccbd47555048def9cd08da220c74 We need the tty/serial fixes in here as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
We need the tty/serial fixes in here as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: core: don't use snprintf() for formatting sysfs attrs 2020-08-28T08:26:47+00:00 Alex Dewar alex.dewar90@gmail.com 2020-08-24T22:39:33+00:00 9cfbf7a6416b5fa2b88ac337d092be82778a0469 As per the documentation (Documentation/filesystems/sysfs.rst), snprintf() should not be used for formatting values returned by sysfs. For all of the instances in serial_core.c, we know that the string will be <PAGE_SIZE in length, so just use sprintf(). Issue identified by Coccinelle. Signed-off-by: Alex Dewar <alex.dewar90@gmail.com> Link: https://lore.kernel.org/r/20200824223932.27709-1-alex.dewar90@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
As per the documentation (Documentation/filesystems/sysfs.rst),
snprintf() should not be used for formatting values returned by sysfs.

For all of the instances in serial_core.c, we know that the string will
be <PAGE_SIZE in length, so just use sprintf().

Issue identified by Coccinelle.

Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
Link: https://lore.kernel.org/r/20200824223932.27709-1-alex.dewar90@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
treewide: Use fallthrough pseudo-keyword 2020-08-23T22:36:59+00:00 Gustavo A. R. Silva gustavoars@kernel.org 2020-08-23T22:36:59+00:00 df561f6688fef775baa341a0f5d960becd248b11 Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> 
Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>