diff mbox series

[v3,hmm,10/12] mm/hmm: Do not use list*_rcu() for hmm->ranges

Message ID 20190614004450.20252-11-jgg@ziepe.ca (mailing list archive)
State Changes Requested
Delegated to: Jason Gunthorpe
Headers show
Series mm/hmm: Various revisions from a locking/code review | expand

Commit Message

Jason Gunthorpe June 14, 2019, 12:44 a.m. UTC 
From: Jason Gunthorpe <jgg@mellanox.com>

This list is always read and written while holding hmm->lock so there is
no need for the confusing _rcu annotations.

Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Acked-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Ira Weiny <iweiny@intel.com>
Tested-by: Philip Yang <Philip.Yang@amd.com>
---
 mm/hmm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Christoph Hellwig June 15, 2019, 2:18 p.m. UTC | #1 
On Thu, Jun 13, 2019 at 09:44:48PM -0300, Jason Gunthorpe wrote:
>  	range->hmm = hmm;
>  	kref_get(&hmm->kref);
> -	list_add_rcu(&range->list, &hmm->ranges);
> +	list_add(&range->list, &hmm->ranges);
>  
>  	/*
>  	 * If there are any concurrent notifiers we have to wait for them for
> @@ -934,7 +934,7 @@ void hmm_range_unregister(struct hmm_range *range)
>  	struct hmm *hmm = range->hmm;
>  
>  	mutex_lock(&hmm->lock);
> -	list_del_rcu(&range->list);
> +	list_del(&range->list);
>  	mutex_unlock(&hmm->lock);

Looks fine:

Signed-off-by: Christoph Hellwig <hch@lst.de>

Btw, is there any reason new ranges are added to the front and not the
tail of the list?
Jason Gunthorpe June 18, 2019, 12:38 a.m. UTC | #2 
On Sat, Jun 15, 2019 at 07:18:26AM -0700, Christoph Hellwig wrote:
> On Thu, Jun 13, 2019 at 09:44:48PM -0300, Jason Gunthorpe wrote:
> >  	range->hmm = hmm;
> >  	kref_get(&hmm->kref);
> > -	list_add_rcu(&range->list, &hmm->ranges);
> > +	list_add(&range->list, &hmm->ranges);
> >  
> >  	/*
> >  	 * If there are any concurrent notifiers we have to wait for them for
> > @@ -934,7 +934,7 @@ void hmm_range_unregister(struct hmm_range *range)
> >  	struct hmm *hmm = range->hmm;
> >  
> >  	mutex_lock(&hmm->lock);
> > -	list_del_rcu(&range->list);
> > +	list_del(&range->list);
> >  	mutex_unlock(&hmm->lock);
> 
> Looks fine:
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> 
> Btw, is there any reason new ranges are added to the front and not the
> tail of the list?

Couldn't find one. I think order on this list doesn't matter.

Jason
diff mbox series

Patch

diff --git a/mm/hmm.c b/mm/hmm.c
index e214668cba3474..26af511cbdd075 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -908,7 +908,7 @@  int hmm_range_register(struct hmm_range *range,
 
 	range->hmm = hmm;
 	kref_get(&hmm->kref);
-	list_add_rcu(&range->list, &hmm->ranges);
+	list_add(&range->list, &hmm->ranges);
 
 	/*
 	 * If there are any concurrent notifiers we have to wait for them for
@@ -934,7 +934,7 @@  void hmm_range_unregister(struct hmm_range *range)
 	struct hmm *hmm = range->hmm;
 
 	mutex_lock(&hmm->lock);
-	list_del_rcu(&range->list);
+	list_del(&range->list);
 	mutex_unlock(&hmm->lock);
 
 	/* Drop reference taken by hmm_range_register() */