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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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