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23722fb467
With lockdeps enabled, we get the following warning:
======================================================
WARNING: possible circular locking dependency detected
------------------------------------------------------
kworker/u12:1/53 is trying to acquire lock:
ffff80000adce220 (coresight_mutex){+.+.}-{4:4}, at: coresight_set_assoc_ectdev_mutex+0x3c/0x5c
but task is already holding lock:
ffff80000add1f60 (ect_mutex){+.+.}-{4:4}, at: cti_probe+0x318/0x394
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (ect_mutex){+.+.}-{4:4}:
__mutex_lock_common+0xd8/0xe60
mutex_lock_nested+0x44/0x50
cti_add_assoc_to_csdev+0x4c/0x184
coresight_register+0x2f0/0x314
tmc_probe+0x33c/0x414
-> #0 (coresight_mutex){+.+.}-{4:4}:
__lock_acquire+0x1a20/0x32d0
lock_acquire+0x160/0x308
__mutex_lock_common+0xd8/0xe60
mutex_lock_nested+0x44/0x50
coresight_set_assoc_ectdev_mutex+0x3c/0x5c
cti_update_conn_xrefs+0x6c/0xf8
cti_probe+0x33c/0x394
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(ect_mutex);
lock(coresight_mutex);
lock(ect_mutex);
lock(coresight_mutex);
*** DEADLOCK ***
4 locks held by kworker/u12:1/53:
#0: ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x1fc/0x63c
#1: (deferred_probe_work){+.+.}-{0:0}, at: process_one_work+0x228/0x63c
#2: (&dev->mutex){....}-{4:4}, at: __device_attach+0x48/0x1a8
#3: (ect_mutex){+.+.}-{4:4}, at: cti_probe+0x318/0x394
To fix the same, call cti_add_assoc_to_csdev without the holding
coresight_mutex and confine the locking while setting the associated
ect / cti device using coresight_set_assoc_ectdev_mutex().
Fixes: 177af8285b ("coresight: cti: Enable CTI associated with devices")
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20220721130329.3787211-1-sudeep.holla@arm.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.