i3c: master: Fix recursive locking during device registration

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i3c_master_register_new_i3c_devs() registers newly discovered devices
while holding i3c_bus_normaluse_lock(), a down_read().  device_register()
can immediately probe the device, and probe callbacks typically invoke
I3C helpers that take i3c_bus_normaluse_lock() again, leading to a
recursive acquisition of the same rwsem.  rwsems do not support recursive
read locking and can deadlock when a writer is waiting.  See the
"Recursive read locks" section of Documentation/locking/lockdep-design.rst.

For example, with Intel LPSS I3C, LOCKDEP generates a WARNING like:
  # echo intel-lpss-i3c.0 > /sys/bus/platform/drivers/mipi-i3c-hci/unbind
  # echo intel-lpss-i3c.0 > /sys/bus/platform/drivers/mipi-i3c-hci/bind
  WARNING: possible recursive locking detected
  kworker/5:1/94 is trying to acquire lock:
  ffff88811c810d78 (&i3cbus->lock){++++}-{4:4}, at: i3c_device_match_id+0x45/0x370
  but task is already holding lock:
  ffff88811c810d78 (&i3cbus->lock){++++}-{4:4}, at: i3c_master_reg_work_fn+0x21/0x5f0

Fix this by separating device creation from device registration.
Populate desc->dev under the maintenance lock, collect the devices that
still need registration into a local list, then release the lock before
calling device_register().  Finally retake the lock and clean up any
devices that failed to register.

Use the maintenance lock rather than the normal-use lock while adding
device objects.  A write-side maintenance lock prevents readers from
observing a partially initialized desc->dev during initial device
population, or desc->dev disappearing if registration fails.

The local list requires a list node, so add a list node member to struct
i3c_device.

Fixes: 3a379bbcea ("i3c: Add core I3C infrastructure")
Cc: stable@vger.kernel.org
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260807145638.168865-2-adrian.hunter@intel.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

...

This commit is contained in:

Adrian Hunter 2026-08-07 17:56:25 +03:00 • committed by Alexandre Belloni

parent 2cdb9c2138

commit 456f832e5f

2 changed files with 36 additions and 12 deletions

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45

drivers/i3c/master.c

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3

include/linux/i3c/master.h

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