Messages in this thread | | | From | Linus Torvalds <> | Date | Sat, 13 Aug 2022 13:27:40 -0700 | Subject | Re: [GIT PULL] timer fixes |
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On Sat, Aug 13, 2022 at 9:25 AM Borislav Petkov <bp@alien8.de> wrote: > > That task_struct.sighand is marked __rcu and thus noderef and sparse > complains:
I think that RCU marking is misleading.
Doing a
git grep -e '->sighand'
shows that we basically never treat that as some kind of RCU pointer.
Adding a
grep -i rcu
to the above shows that we have a couple of places that do this carefully, but they are the exception rather than the rule.
I think the issue is that "current->sighand" is always safe (and that "me->sighand" is the same thing), and that sighand has RCU-delayed freeing so that __lock_task_sighand() can safely try to take the lock of another process' sighand.
And we have no real way to explain to sparse that *some* cases are fine, others are not and need the sighand lock (after that careful __lock_task_sighand thing).
Linus
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