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Message-ID: <ZyGwemWwixBA+VIh@Asurada-Nvidia>
Date: Tue, 29 Oct 2024 21:05:14 -0700
From: Nicolin Chen <nicolinc@...dia.com>
To: Jason Gunthorpe <jgg@...dia.com>
CC: <kevin.tian@...el.com>, <will@...nel.org>, <joro@...tes.org>,
<suravee.suthikulpanit@....com>, <robin.murphy@....com>,
<dwmw2@...radead.org>, <baolu.lu@...ux.intel.com>, <shuah@...nel.org>,
<linux-kernel@...r.kernel.org>, <iommu@...ts.linux.dev>,
<linux-arm-kernel@...ts.infradead.org>, <linux-kselftest@...r.kernel.org>,
<eric.auger@...hat.com>, <jean-philippe@...aro.org>, <mdf@...nel.org>,
<mshavit@...gle.com>, <shameerali.kolothum.thodi@...wei.com>,
<smostafa@...gle.com>, <yi.l.liu@...el.com>, <aik@....com>,
<zhangfei.gao@...aro.org>, <patches@...ts.linux.dev>
Subject: Re: [PATCH v5 03/13] iommufd: Add iommufd_verify_unfinalized_object
On Tue, Oct 29, 2024 at 03:55:58PM -0300, Jason Gunthorpe wrote:
> On Tue, Oct 29, 2024 at 09:18:05AM -0700, Nicolin Chen wrote:
> > I think we'd need the same change in iommufd_object_abort() too.
>
> Makes sense
I found xa_cmpxchg() does xas_result to its returning value, which
turns XA_ZERO_ENTRY into NULL failing our intended verifications.
So, I replaced that further with xas_store:
-----------------------------------------------------------------
@@ -41,20 +41,26 @@ static struct miscdevice vfio_misc_dev;
void iommufd_object_finalize(struct iommufd_ctx *ictx,
struct iommufd_object *obj)
{
+ XA_STATE(xas, &ictx->objects, obj->id);
void *old;
- old = xa_store(&ictx->objects, obj->id, obj, GFP_KERNEL);
- /* obj->id was returned from xa_alloc() so the xa_store() cannot fail */
- WARN_ON(old);
+ xa_lock(&ictx->objects);
+ old = xas_store(&xas, obj);
+ xa_unlock(&ictx->objects);
+ /* obj->id was returned from xa_alloc() so the xas_store() cannot fail */
+ WARN_ON(old != XA_ZERO_ENTRY);
}
/* Undo _iommufd_object_alloc() if iommufd_object_finalize() was not called */
void iommufd_object_abort(struct iommufd_ctx *ictx, struct iommufd_object *obj)
{
+ XA_STATE(xas, &ictx->objects, obj->id);
void *old;
- old = xa_erase(&ictx->objects, obj->id);
- WARN_ON(old);
+ xa_lock(&ictx->objects);
+ old = xas_store(&xas, NULL);
+ xa_unlock(&ictx->objects);
+ WARN_ON(old != XA_ZERO_ENTRY);
kfree(obj);
}
-----------------------------------------------------------------
Thanks
Nicolin
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