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rculist: Add brackets around cond argument in __list_check_rcu macro
authorAmol Grover <frextrite@gmail.com>
Sat, 18 Jan 2020 16:54:18 +0000 (22:24 +0530)
committerPaul E. McKenney <paulmck@kernel.org>
Thu, 20 Feb 2020 23:58:23 +0000 (15:58 -0800)
commit4dfd5cd83dc4458049c7f6eb9c4f361acc4239ea
tree77997758f8b5f1d2a6615c69428ab57d74738040
parentaa24f93753e256c4b14fe46f7261f150cff2a50c
rculist: Add brackets around cond argument in __list_check_rcu macro

Passing a complex lockdep condition to __list_check_rcu results
in false positive lockdep splat due to incorrect expression
evaluation.

For example, a lockdep check condition `cond1 || cond2` is
evaluated as `!cond1 || cond2 && !rcu_read_lock_any_held()`
which, according to operator precedence, evaluates to
`!cond1 || (cond2 && !rcu_read_lock_any_held())`.
This would result in a lockdep splat when cond1 is false
and cond2 is true which is logically incorrect.

Signed-off-by: Amol Grover <frextrite@gmail.com>
Acked-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
include/linux/rculist.h