> On Dec 12, 2023, at 12:27 PM, Neeraj Upadhyay (AMD) <neeraj.iitr10@xxxxxxxxx> wrote: > > From: "Paul E. McKenney" <paulmck@xxxxxxxxxx> > > Currently, the reader/updater compatibility rules for the three RCU > Tasks flavors are squished together in a single paragraph, which can > result in confusion. This commit therefore splits them out into a list, > clearly showing the distinction between these flavors. > > Link: https://lore.kernel.org/all/20231002211936.5948253e@xxxxxxxxxxxxxxxxxx/ > > Reported-by: Steven Rostedt <rostedt@xxxxxxxxxxx> > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> > Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> > Reviewed-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx> > Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.iitr10@xxxxxxxxx> > --- > Documentation/RCU/checklist.rst | 25 ++++++++++++++++--------- > 1 file changed, 16 insertions(+), 9 deletions(-) > > diff --git a/Documentation/RCU/checklist.rst b/Documentation/RCU/checklist.rst > index bd3c58c44bef..c432899aff22 100644 > --- a/Documentation/RCU/checklist.rst > +++ b/Documentation/RCU/checklist.rst > @@ -241,15 +241,22 @@ over a rather long period of time, but improvements are always welcome! > srcu_struct. The rules for the expedited RCU grace-period-wait > primitives are the same as for their non-expedited counterparts. > > - If the updater uses call_rcu_tasks() or synchronize_rcu_tasks(), > - then the readers must refrain from executing voluntary > - context switches, that is, from blocking. If the updater uses > - call_rcu_tasks_trace() or synchronize_rcu_tasks_trace(), then > - the corresponding readers must use rcu_read_lock_trace() and > - rcu_read_unlock_trace(). If an updater uses call_rcu_tasks_rude() > - or synchronize_rcu_tasks_rude(), then the corresponding readers > - must use anything that disables preemption, for example, > - preempt_disable() and preempt_enable(). > + Similarly, it is necssary to correctly use the RCU Tasks flavors: Typo: necessary. Probably no need to resend this one, just fix in the PR. Thanks, - Joel > + > + a. If the updater uses synchronize_rcu_tasks() or > + call_rcu_tasks(), then the readers must refrain from > + executing voluntary context switches, that is, from > + blocking. > + > + b. If the updater uses call_rcu_tasks_trace() > + or synchronize_rcu_tasks_trace(), then the > + corresponding readers must use rcu_read_lock_trace() > + and rcu_read_unlock_trace(). > + > + c. If an updater uses call_rcu_tasks_rude() or > + synchronize_rcu_tasks_rude(), then the corresponding > + readers must use anything that disables preemption, > + for example, preempt_disable() and preempt_enable(). > > Mixing things up will result in confusion and broken kernels, and > has even resulted in an exploitable security issue. Therefore, > -- > 2.40.1 > >
