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SubjectRe: [PATCH v3 2.6.39-rc1-tip 18/26] 18: uprobes: commonly used filters.
* Peter Zijlstra <peterz@infradead.org> [2011-04-19 15:57:57]:

> On Fri, 2011-04-01 at 20:06 +0530, Srikar Dronamraju wrote:
> > Provides most commonly used filters that most users of uprobes can
> > reuse. However this would be useful once we can dynamically associate a
> > filter with a uprobe-event tracer.
> >
> > Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> > ---
> > include/linux/uprobes.h | 5 +++++
> > kernel/uprobes.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++
> > 2 files changed, 55 insertions(+), 0 deletions(-)
> >
> > diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
> > index 26c4d78..34b989f 100644
> > --- a/include/linux/uprobes.h
> > +++ b/include/linux/uprobes.h
> > @@ -65,6 +65,11 @@ struct uprobe_consumer {
> > struct uprobe_consumer *next;
> > };
> >
> > +struct uprobe_simple_consumer {
> > + struct uprobe_consumer consumer;
> > + pid_t fvalue;
> > +};
> > +
> > struct uprobe {
> > struct rb_node rb_node; /* node in the rb tree */
> > atomic_t ref;
> > diff --git a/kernel/uprobes.c b/kernel/uprobes.c
> > index cdd52d0..c950f13 100644
> > --- a/kernel/uprobes.c
> > +++ b/kernel/uprobes.c
> > @@ -1389,6 +1389,56 @@ int uprobe_post_notifier(struct pt_regs *regs)
> > return 0;
> > }
> >
> > +bool uprobes_pid_filter(struct uprobe_consumer *self, struct task_struct *t)
> > +{
> > + struct uprobe_simple_consumer *usc;
> > +
> > + usc = container_of(self, struct uprobe_simple_consumer, consumer);
> > + if (t->tgid == usc->fvalue)
> > + return true;
> > + return false;
> > +}
> > +
> > +bool uprobes_tid_filter(struct uprobe_consumer *self, struct task_struct *t)
> > +{
> > + struct uprobe_simple_consumer *usc;
> > +
> > + usc = container_of(self, struct uprobe_simple_consumer, consumer);
> > + if (t->pid == usc->fvalue)
> > + return true;
> > + return false;
> > +}
>
> Pretty much everything using t->pid/t->tgid is doing it wrong.
>
> > +bool uprobes_ppid_filter(struct uprobe_consumer *self, struct task_struct *t)
> > +{
> > + pid_t pid;
> > + struct uprobe_simple_consumer *usc;
> > +
> > + usc = container_of(self, struct uprobe_simple_consumer, consumer);
> > + rcu_read_lock();
> > + pid = task_tgid_vnr(t->real_parent);
> > + rcu_read_unlock();
> > +
> > + if (pid == usc->fvalue)
> > + return true;
> > + return false;
> > +}
> > +
> > +bool uprobes_sid_filter(struct uprobe_consumer *self, struct task_struct *t)
> > +{
> > + pid_t pid;
> > + struct uprobe_simple_consumer *usc;
> > +
> > + usc = container_of(self, struct uprobe_simple_consumer, consumer);
> > + rcu_read_lock();
> > + pid = pid_vnr(task_session(t));
> > + rcu_read_unlock();
> > +
> > + if (pid == usc->fvalue)
> > + return true;
> > + return false;
> > +}
>
> And there things go haywire too.
>
> What you want is to save the pid-namespace of the task creating the
> filter in your uprobe_simple_consumer and use that to obtain the task's
> pid for matching with the provided number.
>

Okay, will do by adding the pid-namespace of the task creating the
filter in the uprobe_simple_consumer.


--
Thanks and Regards
Srikar


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