linux-kernel - Re: [PATCH rc 2/2] iommufd/fault: Use a separate spinlock to protect fault->deliver list

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <Z4dLfHIs+rW0zAcu@Asurada-Nvidia>
Date: Tue, 14 Jan 2025 21:45:32 -0800
From: Nicolin Chen <nicolinc@...dia.com>
To: Baolu Lu <baolu.lu@...ux.intel.com>
CC: <jgg@...dia.com>, <kevin.tian@...el.com>, <iommu@...ts.linux.dev>,
	<linux-kernel@...r.kernel.org>, <joro@...tes.org>, <will@...nel.org>,
	<robin.murphy@....com>
Subject: Re: [PATCH rc 2/2] iommufd/fault: Use a separate spinlock to protect
 fault->deliver list

On Wed, Jan 15, 2025 at 01:24:53PM +0800, Baolu Lu wrote:
> On 1/15/25 07:28, Nicolin Chen wrote:
> > @@ -445,12 +445,38 @@ struct iommufd_fault {
> >   	/* The lists of outstanding faults protected by below mutex. */
> 
> It's better to update above comment as well.
> 
> >   	struct mutex mutex;
> > +	spinlock_t lock; /* protects the deliver list */
> >   	struct list_head deliver;
> >   	struct xarray response;

Ack. I'll do:
-	/* The lists of outstanding faults protected by below mutex. */
-	struct mutex mutex;
+	spinlock_t lock; /* protects the deliver list */
 	struct list_head deliver;
+	struct mutex mutex; /* serializes response flows */
 	struct xarray response;

> >   	struct wait_queue_head wait_queue;
> >   };
> > +/* Extract the first node out of the fault->deliver list */
> > +static inline struct iopf_group *
> > +iommufd_fault_deliver_extract(struct iommufd_fault *fault)
> > +{
> > +	struct list_head *list = &fault->deliver;
> > +	struct iopf_group *group = NULL;
> > +
> > +	spin_lock(&fault->lock);
> > +	if (!list_empty(list)) {
> > +		group = list_first_entry(list, struct iopf_group, node);
> > +		list_del(&group->node);
> > +	}
> > +	spin_unlock(&fault->lock);
> > +	return group;
> > +}
> > +
> > +/* Restore a node back to the head in fault->deliver */
> > +static inline void iommufd_fault_deliver_restore(struct iommufd_fault *fault,
> > +						 struct iopf_group *group)
> > +{
> > +	spin_lock(&fault->lock);
> > +	list_add(&fault->deliver, &group->node);
> 
> This is not right. It should be
> 
> 	list_add(&group->node, &fault->deliver);
> 
> > +	spin_unlock(&fault->lock);
> > +}

Oh, right!

> Others look good to me. With above addressed,
> 
> Reviewed-by: Lu Baolu <baolu.lu@...ux.intel.com>

Thanks!
Nicolin