Quoting Sukadev Bhattiprolu ([email protected]): > From: Sukadev Bhattiprolu <[email protected]> > Date: Fri, 12 Dec 2008 11:49:27 -0800 > Subject: [PATCH 2/2] pid: Generalize task_active_pid_ns > > Currently task_active_pid_ns is not safe to call after a > task becomes a zombie and exit_task_namespaces is called, > as nsproxy becomes NULL. By reading the pid namespace from > the pid of the task we can trivially solve this problem at > the cost of one extra memory read in what should be the > same cacheline as we read the namespace from. > > When moving things around I have made task_active_pid_ns > out of line because keeping it in pid_namespace.h would > require adding includes of pid.h and sched.h that I > don't think we want. > > This change does make task_active_pid_ns unsafe to call during > copy_process until we attach a pid on the task_struct which > seems to be a reasonable trade off.
Yeah that's not really much of a tradeoff... the text for those lines gets shorter! :) Acked-by: Serge Hallyn <[email protected]> (to all three) thanks, -serge > Signed-off-by: Eric W. Biederman <[email protected]> > --- > include/linux/pid_namespace.h | 6 +----- > kernel/fork.c | 4 ++-- > kernel/pid.c | 6 ++++++ > 3 files changed, 9 insertions(+), 7 deletions(-) > > diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h > index d82fe82..38d1032 100644 > --- a/include/linux/pid_namespace.h > +++ b/include/linux/pid_namespace.h > @@ -79,11 +79,7 @@ static inline void zap_pid_ns_processes(struct > pid_namespace *ns) > } > #endif /* CONFIG_PID_NS */ > > -static inline struct pid_namespace *task_active_pid_ns(struct task_struct > *tsk) > -{ > - return tsk->nsproxy->pid_ns; > -} > - > +extern struct pid_namespace *task_active_pid_ns(struct task_struct *tsk); > void pidhash_init(void); > void pidmap_init(void); > > diff --git a/kernel/fork.c b/kernel/fork.c > index dba2d3f..9fa1d91 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -1100,12 +1100,12 @@ static struct task_struct *copy_process(unsigned long > clone_flags, > > if (pid != &init_struct_pid) { > retval = -ENOMEM; > - pid = alloc_pid(task_active_pid_ns(p)); > + pid = alloc_pid(p->nsproxy->pid_ns); > if (!pid) > goto bad_fork_cleanup_io; > > if (clone_flags & CLONE_NEWPID) { > - retval = pid_ns_prepare_proc(task_active_pid_ns(p)); > + retval = pid_ns_prepare_proc(p->nsproxy->pid_ns); > if (retval < 0) > goto bad_fork_free_pid; > } > diff --git a/kernel/pid.c b/kernel/pid.c > index 064e76a..c5513fe 100644 > --- a/kernel/pid.c > +++ b/kernel/pid.c > @@ -474,6 +474,12 @@ pid_t task_session_nr_ns(struct task_struct *tsk, struct > pid_namespace *ns) > } > EXPORT_SYMBOL(task_session_nr_ns); > > +struct pid_namespace *task_active_pid_ns(struct task_struct *tsk) > +{ > + return ns_of_pid(task_pid(tsk)); > +} > +EXPORT_SYMBOL_GPL(task_active_pid_ns); > + > /* > * Used by proc to find the first pid that is greater then or equal to nr. > * > -- > 1.5.2.5 > > _______________________________________________ > Containers mailing list > [email protected] > https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
