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Re: [RFC] [PATCH 2.6.37-rc5-tip 14/20] 14: uprobes: Handing int3 and singlestep exception.
- From: Peter Zijlstra <peterz at infradead dot org>
- To: Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>
- Cc: Ingo Molnar <mingo at elte dot hu>, Steven Rostedt <rostedt at goodmis dot org>, Linux-mm <linux-mm at kvack dot org>, Arnaldo Carvalho de Melo <acme at infradead dot org>, Linus Torvalds <torvalds at linux-foundation dot org>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Christoph Hellwig <hch at infradead dot org>, Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>, Oleg Nesterov <oleg at redhat dot com>, LKML <linux-kernel at vger dot kernel dot org>, SystemTap <systemtap at sources dot redhat dot com>, Jim Keniston <jkenisto at linux dot vnet dot ibm dot com>, Frederic Weisbecker <fweisbec at gmail dot com>, Andi Kleen <andi at firstfloor dot org>, Andrew Morton <akpm at linux-foundation dot org>, "Paul E. McKenney" <paulmck at linux dot vnet dot ibm dot com>
- Date: Wed, 26 Jan 2011 11:17:11 +0100
- Subject: Re: [RFC] [PATCH 2.6.37-rc5-tip 14/20] 14: uprobes: Handing int3 and singlestep exception.
- References: <20101216095714.23751.52601.sendpatchset@localhost6.localdomain6> <20101216095957.23751.57040.sendpatchset@localhost6.localdomain6> <1295963779.28776.1059.camel@laptop> <20110126085203.GG19725@linux.vnet.ibm.com>
On Wed, 2011-01-26 at 14:22 +0530, Srikar Dronamraju wrote:
> * Peter Zijlstra <peterz@infradead.org> [2011-01-25 14:56:19]:
>
> > On Thu, 2010-12-16 at 15:29 +0530, Srikar Dronamraju wrote:
> > > + down_read(&mm->mmap_sem);
> > > + for (vma = mm->mmap; vma; vma = vma->vm_next) {
> > > + if (!valid_vma(vma))
> > > + continue;
> > > + if (probept < vma->vm_start || probept > vma->vm_end)
> > > + continue;
> > > + u = find_uprobe(vma->vm_file->f_mapping->host,
> > > + probept - vma->vm_start);
> > > + if (u)
> > > + break;
> > > + }
> > > + up_read(&mm->mmap_sem);
> >
> > One has to ask, what's wrong with find_vma() ?
>
> Are you looking for something like this.
>
> down_read(&mm->mmap_sem);
> for (vma = find_vma(mm, probept); ; vma = vma->vm_next) {
> if (!valid_vma(vma))
> continue;
> u = find_uprobe(vma->vm_file->f_mapping->host,
> probept - vma->vm_start);
> if (u)
> break;
> }
> up_read(&mm->mmap_sem);
How could you ever need to iterate here? There is only a single vma that
covers the probe point, if that doesn't find a uprobe, there isn't any.