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| author |   Neeraj Upadhyay <neeraju@codeaurora.org> | 2021-08-18 12:58:43 +0530 |
|---|---|---|
| committer |   Paul E. McKenney <paulmck@kernel.org> | 2021-09-15 11:41:19 -0700 |
| commit | a6517e9ce0115e33617062c9e73b4c5e6f787525 (patch) | |
| tree | cffd62fe125a583d26fcc58fe65dc99b21b5c04d /kernel/rcu | |
| parent | rcu-tasks: Correct comparisons for CPU numbers in show_stalled_task_trace (diff) | |
| download | linux-dev-a6517e9ce0115e33617062c9e73b4c5e6f787525.tar.xz linux-dev-a6517e9ce0115e33617062c9e73b4c5e6f787525.zip | |
rcu-tasks: Clarify read side section info for rcu_tasks_rude GP primitives
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@codeaurora.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tasks.h | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index af7388849bed..8c63b4d23829 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 |