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Subject: Re: [PATCH v2 2.6.38-rc8-tip 5/20] 5: Uprobes: register/unregister
 probes.
From: Peter Zijlstra <peterz@infradead.org>
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Date: Tue, 15 Mar 2011 18:50:11 +0100
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To: Steven Rostedt <rostedt@goodmis.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@elte.hu>, Linux-mm <linux-mm@kvack.org>, Arnaldo Carvalho de Melo <acme@infradead.org>, Linus Torvalds <torvalds@linux-foundation.org>, Christoph Hellwig <hch@infradead.org>, Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>, Ananth N Mavinakayanahalli <ananth@in.ibm.com>, Oleg Nesterov <oleg@redhat.com>, LKML <linux-kernel@vger.kernel.org>, SystemTap <systemtap@sources.redhat.com>, Jim Keniston <jkenisto@linux.vnet.ibm.com>, Roland McGrath <roland@hack.frob.com>, Andi Kleen <andi@firstfloor.org>, Andrew Morton <akpm@linux-foundation.org>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>

On Tue, 2011-03-15 at 13:47 -0400, Steven Rostedt wrote:
> On Tue, 2011-03-15 at 22:45 +0530, Srikar Dronamraju wrote:
> > > > +   }
> > > > +   list_for_each_entry_safe(mm, tmpmm, &tmp_list, uprobes_list) {
> > > > +           down_read(&mm->mmap_sem);
> > > > +           if (!install_uprobe(mm, uprobe))
> > > > +                   ret =3D 0;
> > >=20
> > > Installing it once is success ?
> >=20
> > This is a little tricky. My intention was to return success even if one
> > install is successful. If we return error, then the caller can go
> > ahead and free the consumer. Since we return success if there are
> > currently no processes that have mapped this inode, I was tempted to
> > return success on atleast one successful install.
>=20
> What about an all or nothing approach. If one fails, remove all that
> were installed, and give up.

That sounds like a much saner semantic and is what we generally do in
the kernel.

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