lkml.org 
[lkml]   [2019]   [Jan]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v3 0/6] Static calls
On Fri, 11 Jan 2019 15:41:22 -0600
Josh Poimboeuf <jpoimboe@redhat.com> wrote:

> > I don’t see RCU-sched solves the problem if you don’t disable preemption. On
> > a fully preemptable kernel, you can get preempted between the push and the
> > call (jmp) or before the push. RCU-sched can then finish, and the preempted
> > task may later jump to a wrong patched-dest.
>
> Argh, I misspoke about RCU-sched. Words are hard.
>
> I meant synchronize_rcu_tasks(), which is a completely different animal.
> My understanding is that it waits until all runnable tasks (including
> preempted tasks) have gotten a chance to run.

Not quite, but does the same thing. It waits for all tasks to either
schedule voluntarily (not preempted), or be / go into idle, or be /go
into userspace. In any case, it makes sure code is off of trampolines.
I use this before freeing trampolines used by ftrace.

-- Steve

\
 
 \ /
  Last update: 2019-01-11 22:56    [W:0.094 / U:0.140 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site