RCU tasks rude variant does not check whether the current running context on a CPU is usermode. Read side critical section ends on transition to usermode execution, by the virtue of usermode execution being schedulable. Clarify this in comments for call_rcu_tasks_rude() and synchronize_rcu_tasks_rude(). Signed-off-by: Neeraj Upadhyay <neeraju@xxxxxxxxxxxxxx> --- kernel/rcu/tasks.h | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index 5f9c14c..702a4fa 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -677,11 +677,11 @@ DEFINE_RCU_TASKS(rcu_tasks_rude, rcu_tasks_rude_wait_gp, call_rcu_tasks_rude, * period elapses, in other words after all currently executing RCU * read-side critical sections have completed. call_rcu_tasks_rude() * assumes that the read-side critical sections end at context switch, - * cond_resched_rcu_qs(), or transition to usermode execution. As such, - * there are no read-side primitives analogous to rcu_read_lock() and - * rcu_read_unlock() because this primitive is intended to determine - * that all tasks have passed through a safe state, not so much for - * data-structure synchronization. + * cond_resched_rcu_qs(), or transition to usermode execution (as + * usermode execution is schedulable). As such, there are no read-side + * primitives analogous to rcu_read_lock() and rcu_read_unlock() because + * this primitive is intended to determine that all tasks have passed + * through a safe state, not so much for data-structure synchronization. * * See the description of call_rcu() for more detailed information on * memory ordering guarantees. @@ -699,8 +699,8 @@ EXPORT_SYMBOL_GPL(call_rcu_tasks_rude); * grace period has elapsed, in other words after all currently * executing rcu-tasks read-side critical sections have elapsed. These * read-side critical sections are delimited by calls to schedule(), - * cond_resched_tasks_rcu_qs(), userspace execution, and (in theory, - * anyway) cond_resched(). + * cond_resched_tasks_rcu_qs(), userspace execution (which is a schedulable + * context), and (in theory, anyway) cond_resched(). * * This is a very specialized primitive, intended only for a few uses in * tracing and other situations requiring manipulation of function preambles -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation
