[ Upstream commit 7b94ea5051 ]
If an i2c topology has instances of nested muxes, then a lockdep splat
is produced when when i2c_parent_lock_bus() is called. Here is an
example:
============================================
WARNING: possible recursive locking detected
--------------------------------------------
insmod/68159 is trying to acquire lock:
(i2c_register_adapter#2){+.+.}, at: i2c_parent_lock_bus+0x32/0x50 [i2c_mux]
but task is already holding lock:
(i2c_register_adapter#2){+.+.}, at: i2c_parent_lock_bus+0x32/0x50 [i2c_mux]
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(i2c_register_adapter#2);
lock(i2c_register_adapter#2);
*** DEADLOCK ***
May be due to missing lock nesting notation
1 lock held by insmod/68159:
#0: (i2c_register_adapter#2){+.+.}, at: i2c_parent_lock_bus+0x32/0x50 [i2c_mux]
stack backtrace:
CPU: 13 PID: 68159 Comm: insmod Tainted: G O
Call Trace:
dump_stack+0x67/0x98
__lock_acquire+0x162e/0x1780
lock_acquire+0xba/0x200
rt_mutex_lock+0x44/0x60
i2c_parent_lock_bus+0x32/0x50 [i2c_mux]
i2c_parent_lock_bus+0x3e/0x50 [i2c_mux]
i2c_smbus_xfer+0xf0/0x700
i2c_smbus_read_byte+0x42/0x70
my2c_init+0xa2/0x1000 [my2c]
do_one_initcall+0x51/0x192
do_init_module+0x62/0x216
load_module+0x20f9/0x2b50
SYSC_init_module+0x19a/0x1c0
SyS_init_module+0xe/0x10
do_syscall_64+0x6c/0x1a0
entry_SYSCALL_64_after_hwframe+0x42/0xb7
Reported-by: John Sperbeck <jsperbeck@google.com>
Tested-by: John Sperbeck <jsperbeck@google.com>
Signed-off-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Deepa Dinamani <deepadinamani@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Chang <dpf@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Wolfram Sang <wsa@the-dreams.de>
Link: http://lkml.kernel.org/r/20180720083914.1950-3-peda@axentia.se
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit e0638fa400 upstream.
Reference count of device node was increased in of_i2c_register_device,
but without decreasing it in i2c_unregister_device. Then the added
device node will never be released. Fix this by adding the of_node_put.
Signed-off-by: Lixin Wang <alan.1.wang@nokia-sbell.com>
Tested-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
I2C drivers were required to have an I2C device ID table even if were for
devices that would only be registered using a specific firmware interface
(e.g: OF or ACPI).
But commit da10c06a04 ("i2c: Make I2C ID tables non-mandatory for DT'ed
devices") changed the I2C core to relax the requirement and allow drivers
to avoid defining this table.
Unfortunately it only took into account drivers for OF-only devices and
forgot about ACPI-only ones, and this was fixed by commit c64ffff7a9
("i2c: core: Allow empty id_table in ACPI case as well").
But the latter didn't update the original comment, so it doesn't reflect
what the code does now.
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
For now empty ID table is not allowed with ACPI and prevents driver to
be probed.
Add a check to allow empty ID table.
This introduces a helper i2c_acpi_match_device().
Note, we rename some static function in i2c-core-acpi.c to distinguish
with public API.
Fixes: da10c06a04 ("i2c: Make I2C ID tables non-mandatory for DT'ed devices")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Rajmohan Mani <rajmohan.mani@intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
[wsa: needed to get some drivers probed again]
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Finally, apply modern comment rules to the file header. The old style
looked very non-Linuxish and challenged my eyes for some time now. I
also added my own copyright for the period of me being the maintainer.
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
They seem like cruft to me. I couldn't find any evidence that something
included from there is actually used.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Removes some ifdeffery. Also add the new file to the relevant
MAINTAINERS section.
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Break out the exported SMBus functions and the emulation layer into a
separate file. This also involved splitting up the tracing header into
an I2C and an SMBus part.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
The I2C core became quite huge and its monolithic structure makes
maintenance hard. So, prepare to break out some functionality into
separate files by renaming the source file. Note that we keep the
resulting object name constant to avoid regressions.
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
