Re: [patch] ac17: alpha ptrace fix

From: Manfred Spraul (manfred@colorfullife.com)
Date: Tue Jun 13 2000 - 11:51:19 EST

Philipp Rumpf wrote:
>
> On Tue, Jun 13, 2000 at 02:52:02PM +0400, Ivan Kokshaysky wrote:
> > Just an obvious 'search & replace' changes.
> >
> > Ivan.
> >

Could you also add get_task_struct() as on i386? Otherwise the task may
disappear immediately after find_task_by_pid().
Hmm read_lock(&tasklist_lock) is also missing ;)

>
> Philipp Rumpf
>
Philipp,
what about adding a comment in <linux/sched.h> about the locking of the
new ptrace variable?

* it seesm that ->ptrace is protected the big kernel lock.
* ->tty, ->mm, ->files, ->fs are written by "current" +
current->alloc_lock.
* the signal pointers are protected by sigmask_lock (1)
* hopefully all other fields are only written by "current"

(1) current->sig->action[] is not yet SMP safe: threads can share the
signal struct, but they don't share the siglockmask spinlock ;)
Isn't spin_lock(&current->sig->siglock) missing? 

--
	Manfred

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