[0/2] Add lockdep_assert_not_held()

Message

Shuah Khan Feb. 12, 2021, 11:28 p.m. UTC

Some kernel functions must not be called holding a specific lock. Doing
so could lead to locking problems. Currently these routines call
lock_is_held() to check for lock hold followed by WARN_ON.

Adding a common lockdep interface will help reduce the duplication of this
logic in the rest of the kernel.

Add lockdep_assert_not_held() to be used in these functions to detect
incorrect calls while holding a lock.

lockdep_assert_not_held() provides the opposite functionality of
lockdep_assert_held() which is used to assert calls that require
holding a specific lock.

The need for lockdep_assert_not_held() came up in a discussion on
ath10k patch. ath10k_drain_tx() and i915_vma_pin_ww() are examples
of functions that can use lockdep_assert_not_held().

Link: https://lore.kernel.org/linux-wireless/[e-mail]/

This patch series adds lockdep_assert_not_held() and uses it in the
second patch in ath10k_drain_tx() function.

Shuah Khan (2):
  lockdep: add lockdep_assert_not_held()
  ath10k: detect conf_mutex held ath10k_drain_tx() calls

 drivers/net/wireless/ath/ath10k/mac.c | 2 ++
 include/linux/lockdep.h               | 7 ++++++-
 2 files changed, 8 insertions(+), 1 deletion(-)