| Message ID | CAFLxGvwpwYh+hMN0VUW8jvhrXek4=MLSmGSiOCHXRA1euNzrfw@mail.gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
...of course I meant t-> and not current-> On 5/1/15, Richard Weinberger <richard.weinberger@gmail.com> wrote: > On Fri, May 1, 2015 at 8:37 PM, Linus Torvalds > <torvalds@linux-foundation.org> wrote: >> "flush_signals()" is only for kernel threads, where it's a hacky >> alternative to actually handling them (since kernel threads never >> rreturn to user space and cannot really "handle" a signal). But you're >> doing it in the ->remove handler for the device, which can be called >> by arbitrary system processes. This is not a kernel thread thing, as >> far as I can see. >> >> If you cannot handle signals, you damn well shouldn't be using >> "wait_event_interruptible_timeout()" to begin with. Get rid of the >> "interruptible", since it apparently *isn't* interruptible. >> >> So I'm not pulling this. >> >> Now I'm worried that other drivers do insane things like this. I >> wonder if we should add some sanity test to flush_signals() to make >> sure that it can only ever get called from a kernel thread. > > Hmm, a quick grep exposes some questionable users. > At least w1 looks fishy. > drivers/w1/w1_family.c:w1_unregister_family > drivers/w1/w1_int.c:__w1_remove_master_device > > What do you think about a WARN_ON like: > > diff --git a/kernel/signal.c b/kernel/signal.c > index d51c5dd..b4079c3 100644 > --- a/kernel/signal.c > +++ b/kernel/signal.c > @@ -427,6 +427,8 @@ void flush_signals(struct task_struct *t) > { > unsigned long flags; > > + WARN_ON((current->flags & PF_KTHREAD) == 0); > + > spin_lock_irqsave(&t->sighand->siglock, flags); > __flush_signals(t); > spin_unlock_irqrestore(&t->sighand->siglock, flags); > > -- > Thanks, > //richard >
diff --git a/kernel/signal.c b/kernel/signal.c index d51c5dd..b4079c3 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -427,6 +427,8 @@ void flush_signals(struct task_struct *t) { unsigned long flags; + WARN_ON((current->flags & PF_KTHREAD) == 0); + spin_lock_irqsave(&t->sighand->siglock, flags); __flush_signals(t); spin_unlock_irqrestore(&t->sighand->siglock, flags);