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items: [RFC][PATCH 06/14] Populate pid_nrs list with entry for init-pid-ns
items: Re: [RFC][PATCH 06/14] Populate pid_nrs list with entry for init-pid-ns

[RFC][PATCH 06/14] Populate pid_nrs list with entry for init-pid-ns
type: item
description: From: Cedric Le Goater <clg@fr.ibm.com> Subject: [RFC][PATCH 06/14] Populate pid_nrs list with entry for init-pid-ns Create/destroy the pid->pid_nrs list - when allocating/freeing a struct pid. The pid_nrs list contains just a single struct pid_nr for now, (corresponding to init-pid-ns). To enable finding a process based on any of its pid_t values, replace the use struct pid_nr, rather than struct pid, in the pid_hash table. Finally, reimplement find_pid() and pid_nr() based on the pid_nrs list. Changelog: - [Serge Hallyn's comment]: Add comments on what pid->lock protects and that pid->nr will eventually go away. - [Eric Biederman and containers list comments]: Reworked patches to drop support for unsharing pid namespace and to replace struct pid with struct pid_nr in the pid_hash table. Signed-off-by: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com> --- include/linux/pid.h | 9 ------ kernel/pid.c | 73 ++++++++++++++++++++++++++++++++++------------------ 2 files changed, 50 insertions(+), 32 deletions(-) Index: 2.6.21-rc3-mm2/kernel/pid.c =================================================================== --- 2.6.21-rc3-mm2.orig/kernel/pid.c +++ 2.6.21-rc3-mm2/kernel/pid.c @@ -194,8 +194,15 @@ static void delayed_put_pid(struct rcu_h void free_pid_nr(struct pid_nr *pid_nr) { + /* We can be called with write_lock_irq(&tasklist_lock) held */ + unsigned long flags; + free_pidmap(pid_nr->pid_ns, pid_nr->nr); + spin_lock_irqsave(&pidmap_lock, flags); + hlist_del_rcu(&pid_nr->pid_chain); + spin_unlock_irqrestore(&pidmap_lock, flags); + hlist_del_init(&pid_nr->node); put_pid_ns(pid_nr->pid_ns); @@ -204,14 +211,12 @@ void free_pid_nr(struct pid_nr *pid_nr) fastcall void free_pid(struct pid *pid) { - /* We can be called with write_lock_irq(&tasklist_lock) held */ - unsigned long flags; + struct pid_nr *pid_nr; + struct hlist_node *pos, *next; - spin_lock_irqsave(&pidmap_lock, flags); - hlist_del_rcu(&pid->pid_chain); - spin_unlock_ir…
creator: Sukadev Bhattiprolu
date: 2007-03-21T03:20:04-00:00

Re: [RFC][PATCH 06/14] Populate pid_nrs list with entry for init-pid-ns
type: item
description: sukadev@us.ibm.com writes: > From: Cedric Le Goater <clg@fr.ibm.com> > Subject: [RFC][PATCH 06/14] Populate pid_nrs list with entry for init-pid-ns > > Create/destroy the pid->pid_nrs list - when allocating/freeing a struct pid. > The pid_nrs list contains just a single struct pid_nr for now, (corresponding > to init-pid-ns). > > To enable finding a process based on any of its pid_t values, replace the > use struct pid_nr, rather than struct pid, in the pid_hash table. > > Finally, reimplement find_pid() and pid_nr() based on the pid_nrs list. > > Changelog: > - [Serge Hallyn's comment]: Add comments on what pid->lock protects > and that pid->nr will eventually go away. > - [Eric Biederman and containers list comments]: Reworked patches > to drop support for unsharing pid namespace and to replace > struct pid with struct pid_nr in the pid_hash table. > > Signed-off-by: Cedric Le Goater <clg@fr.ibm.com> > Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com> > --- > include/linux/pid.h | 9 ------ > kernel/pid.c | 73 ++++++++++++++++++++++++++++++++++------------------ > 2 files changed, 50 insertions(+), 32 deletions(-) > > @@ -242,50 +247,70 @@ struct pid_nr *alloc_pid_nr(struct pid_n > */ > pid_nr->pid = pid; > > + spin_lock_irq(&pidmap_lock); > + hlist_add_head_rcu(&pid_nr->pid_chain, &pid_hash[pid_hashfn(nr)]); > + spin_unlock_irq(&pidmap_lock); > + Hmm. I think we really need to hash in some of the bits of the pid_namespace so processes with identical pids don't get put on the same hash chain. It isn't critical but it is a good idea. Eric _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/containers
creator: ebiederm
date: 2007-03-21T09:23:28-00:00

Re: [RFC][PATCH 06/14] Populate pid_nrs list with entry for init-pid-ns
type: item
description: sukadev@us.ibm.com writes: > Signed-off-by: Cedric Le Goater <clg@fr.ibm.com> > Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com> > --- > include/linux/pid.h | 9 ------ > kernel/pid.c | 73 ++++++++++++++++++++++++++++++++++------------------ > 2 files changed, 50 insertions(+), 32 deletions(-) > > @@ -242,50 +247,70 @@ struct pid_nr *alloc_pid_nr(struct pid_n > */ > pid_nr->pid = pid; > > + spin_lock_irq(&pidmap_lock); > + hlist_add_head_rcu(&pid_nr->pid_chain, &pid_hash[pid_hashfn(nr)]); > + spin_unlock_irq(&pidmap_lock); > + Hmm. I think we really need to hash in some of the bits of the pid_namespace so processes with identical pids don't get put on the same hash chain. It isn't critical but it is a good idea. Eric _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/containers
creator: ebiederm
date: 2007-03-21T09:38:14-00:00

Re: [RFC][PATCH 06/14] Populate pid_nrs list with entry for init-pid-ns
type: item
description: On Wed, Mar 21, 2007 at 03:23:28AM -0600, Eric W. Biederman wrote: > sukadev@us.ibm.com writes: > > > From: Cedric Le Goater <clg@fr.ibm.com> > > Subject: [RFC][PATCH 06/14] Populate pid_nrs list with entry for init-pid-ns > > > > Create/destroy the pid->pid_nrs list - when allocating/freeing a struct pid. > > The pid_nrs list contains just a single struct pid_nr for now, (corresponding > > to init-pid-ns). > > > > To enable finding a process based on any of its pid_t values, replace the > > use struct pid_nr, rather than struct pid, in the pid_hash table. > > > > Finally, reimplement find_pid() and pid_nr() based on the pid_nrs list. > > > > Changelog: > > - [Serge Hallyn's comment]: Add comments on what pid->lock protects > > and that pid->nr will eventually go away. > > - [Eric Biederman and containers list comments]: Reworked patches > > to drop support for unsharing pid namespace and to replace > > struct pid with struct pid_nr in the pid_hash table. > > > > Signed-off-by: Cedric Le Goater <clg@fr.ibm.com> > > Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com> > > --- > > include/linux/pid.h | 9 ------ > > kernel/pid.c | 73 ++++++++++++++++++++++++++++++++++------------------ > > 2 files changed, 50 insertions(+), 32 deletions(-) > > > > > @@ -242,50 +247,70 @@ struct pid_nr *alloc_pid_nr(struct pid_n > > */ > > pid_nr->pid = pid; > > > > + spin_lock_irq(&pidmap_lock); > > + hlist_add_head_rcu(&pid_nr->pid_chain, &pid_hash[pid_hashfn(nr)]); > > + spin_unlock_irq(&pidmap_lock); > > + > > Hmm. I think we really need to hash in some of the bits of the > pid_namespace so processes with identical pids don't get put on > the same hash chain. It isn't critical but it is a good idea. yes, can't hurt to distribute that a little, was already thinking about something like this: #define pid_hashfn(nr) hash_long((unsigned long)(nr ^ space), pidhash_shift) as the hash_long should distribute any changes quite evenly ... best, Herbert > Eric > ____________________________…
creator: Herbert Poetzl
date: 2007-03-23T01:27:51-00:00