As reported:
[ 256.104522] ======================================================
[ 256.113783] WARNING: possible circular locking dependency detected
[ 256.120093] 5.16.0-rc6-yocto-standard+ #99 Not tainted
[ 256.125362] ------------------------------------------------------
[ 256.131673] intel-speed-sel/844 is trying to acquire lock:
[ 256.137290] ffffffffc036f0d0 (punit_misc_dev_lock){+.+.}-{3:3}, at: isst_if_open+0x18/0x90 [isst_if_common]
[ 256.147171]
[ 256.147171] but task is already holding lock:
[ 256.153135] ffffffff8ee7cb50 (misc_mtx){+.+.}-{3:3}, at: misc_open+0x2a/0x170
[ 256.160407]
[ 256.160407] which lock already depends on the new lock.
[ 256.160407]
[ 256.168712]
[ 256.168712] the existing dependency chain (in reverse order) is:
[ 256.176327]
[ 256.176327] -> #1 (misc_mtx){+.+.}-{3:3}:
[ 256.181946] lock_acquire+0x1e6/0x330
[ 256.186265] __mutex_lock+0x9b/0x9b0
[ 256.190497] mutex_lock_nested+0x1b/0x20
[ 256.195075] misc_register+0x32/0x1a0
[ 256.199390] isst_if_cdev_register+0x65/0x180 [isst_if_common]
[ 256.205878] isst_if_probe+0x144/0x16e [isst_if_mmio]
...
[ 256.241976]
[ 256.241976] -> #0 (punit_misc_dev_lock){+.+.}-{3:3}:
[ 256.248552] validate_chain+0xbc6/0x1750
[ 256.253131] __lock_acquire+0x88c/0xc10
[ 256.257618] lock_acquire+0x1e6/0x330
[ 256.261933] __mutex_lock+0x9b/0x9b0
[ 256.266165] mutex_lock_nested+0x1b/0x20
[ 256.270739] isst_if_open+0x18/0x90 [isst_if_common]
[ 256.276356] misc_open+0x100/0x170
[ 256.280409] chrdev_open+0xa5/0x1e0
...
The call sequence suggested that misc_device /dev file can be opened
before misc device is yet to be registered, which is done only once.
Here punit_misc_dev_lock was used as common lock, to protect the
registration by multiple ISST HW drivers, one time setup, prevent
duplicate registry of misc device and prevent load/unload when device
is open.
We can split into locks:
- One which just prevent duplicate call to misc_register() and one
time setup. Also never call again if the misc_register() failed or
required one time setup is failed. This lock is not shared with
any misc device callbacks.
- The other lock protects registry, load and unload of HW drivers.
Sequence in isst_if_cdev_register()
- Register callbacks under punit_misc_dev_open_lock
- Call isst_misc_reg() which registers misc_device on the first
registry which is under punit_misc_dev_reg_lock, which is not
shared with callbacks.
Sequence in isst_if_cdev_unregister
Just opposite of isst_if_cdev_register
Reported-and-tested-by: Liwei Song <liwei.song@windriver.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://lore.kernel.org/r/20220112022521.54669-1-srinivas.pandruvada@linux.intel.com
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
17da2d5f93