[2/3] iommufd/device: Make hwpt_list list_add/del symmetric
Commit Message
Since the list_del() of hwpt_item is done in iommufd_device_detach(), move
its list_add_tail() to a similar place in iommufd_device_do_attach().
Also move and place the mutex outside the iommufd_device_auto_get_domain()
and iommufd_device_do_attach() calls, to serialize attach/detach routines.
This adds an additional locking protection so that the following patch can
safely remove devices_lock.
Co-developed-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
drivers/iommu/iommufd/device.c | 26 ++++++++++++--------------
1 file changed, 12 insertions(+), 14 deletions(-)
Comments
Hi Nicolin,
I love your patch! Perhaps something to improve:
[auto build test WARNING on v6.2-rc5]
[also build test WARNING on linus/master next-20230127]
[cannot apply to joro-iommu/next]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Nicolin-Chen/iommufd-Add-devices_users-to-track-the-hw_pagetable-usage-by-device/20230128-150429
patch link: https://lore.kernel.org/r/25b3b85b03fc2a7968c476b0533f451acecdfd13.1674872884.git.nicolinc%40nvidia.com
patch subject: [PATCH 2/3] iommufd/device: Make hwpt_list list_add/del symmetric
config: x86_64-randconfig-a011-20230123 (https://download.01.org/0day-ci/archive/20230128/202301281943.Jdvwci2p-lkp@intel.com/config)
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/4d48fdd86375f6d888bbcf830a10c48720008955
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Nicolin-Chen/iommufd-Add-devices_users-to-track-the-hw_pagetable-usage-by-device/20230128-150429
git checkout 4d48fdd86375f6d888bbcf830a10c48720008955
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/iommu/iommufd/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
All warnings (new ones prefixed by >>):
>> drivers/iommu/iommufd/device.c:279:23: warning: variable 'hwpt' is uninitialized when used here [-Wuninitialized]
lockdep_assert_held(&hwpt->ioas->mutex);
^~~~
include/linux/lockdep.h:319:33: note: expanded from macro 'lockdep_assert_held'
lockdep_assert(lockdep_is_held(l) != LOCK_STATE_NOT_HELD)
^
include/linux/lockdep.h:286:47: note: expanded from macro 'lockdep_is_held'
#define lockdep_is_held(lock) lock_is_held(&(lock)->dep_map)
^~~~
include/linux/lockdep.h:313:32: note: expanded from macro 'lockdep_assert'
do { WARN_ON(debug_locks && !(cond)); } while (0)
^~~~
include/asm-generic/bug.h:122:25: note: expanded from macro 'WARN_ON'
int __ret_warn_on = !!(condition); \
^~~~~~~~~
drivers/iommu/iommufd/device.c:276:35: note: initialize the variable 'hwpt' to silence this warning
struct iommufd_hw_pagetable *hwpt;
^
= NULL
1 warning generated.
vim +/hwpt +279 drivers/iommu/iommufd/device.c
267
268 /*
269 * When automatically managing the domains we search for a compatible domain in
270 * the iopt and if one is found use it, otherwise create a new domain.
271 * Automatic domain selection will never pick a manually created domain.
272 */
273 static int iommufd_device_auto_get_domain(struct iommufd_device *idev,
274 struct iommufd_ioas *ioas)
275 {
276 struct iommufd_hw_pagetable *hwpt;
277 int rc;
278
> 279 lockdep_assert_held(&hwpt->ioas->mutex);
280
281 /*
282 * There is no differentiation when domains are allocated, so any domain
283 * that is willing to attach to the device is interchangeable with any
284 * other.
285 */
286 list_for_each_entry(hwpt, &ioas->hwpt_list, hwpt_item) {
287 if (!hwpt->auto_domain)
288 continue;
289
290 rc = iommufd_device_do_attach(idev, hwpt);
291
292 /*
293 * -EINVAL means the domain is incompatible with the device.
294 * Other error codes should propagate to userspace as failure.
295 * Success means the domain is attached.
296 */
297 if (rc == -EINVAL)
298 continue;
299 return rc;
300 }
301
302 hwpt = iommufd_hw_pagetable_alloc(idev->ictx, ioas, idev->dev);
303 if (IS_ERR(hwpt))
304 return PTR_ERR(hwpt);
305 hwpt->auto_domain = true;
306
307 rc = iommufd_device_do_attach(idev, hwpt);
308 if (rc)
309 goto out_abort;
310
311 iommufd_object_finalize(idev->ictx, &hwpt->obj);
312 return 0;
313
314 out_abort:
315 iommufd_object_abort_and_destroy(idev->ictx, &hwpt->obj);
316 return rc;
317 }
318
On Sat, Jan 28, 2023 at 07:52:54PM +0800, kernel test robot wrote:
> >> drivers/iommu/iommufd/device.c:279:23: warning: variable 'hwpt' is uninitialized when used here [-Wuninitialized]
> lockdep_assert_held(&hwpt->ioas->mutex);
> ^~~~
A mistake here...will fix with a v2:
lockdep_assert_held(&ioas->mutex);
Thanks
Nicolin
@@ -198,6 +198,8 @@ static int iommufd_device_do_attach(struct iommufd_device *idev,
phys_addr_t sw_msi_start = PHYS_ADDR_MAX;
int rc;
+ lockdep_assert_held(&hwpt->ioas->mutex);
+
mutex_lock(&hwpt->devices_lock);
/*
@@ -241,6 +243,7 @@ static int iommufd_device_do_attach(struct iommufd_device *idev,
hwpt->domain);
if (rc)
goto out_detach;
+ list_add_tail(&hwpt->hwpt_item, &hwpt->ioas->hwpt_list);
}
}
@@ -271,12 +274,13 @@ static int iommufd_device_auto_get_domain(struct iommufd_device *idev,
struct iommufd_hw_pagetable *hwpt;
int rc;
+ lockdep_assert_held(&hwpt->ioas->mutex);
+
/*
* There is no differentiation when domains are allocated, so any domain
* that is willing to attach to the device is interchangeable with any
* other.
*/
- mutex_lock(&ioas->mutex);
list_for_each_entry(hwpt, &ioas->hwpt_list, hwpt_item) {
if (!hwpt->auto_domain)
continue;
@@ -290,29 +294,23 @@ static int iommufd_device_auto_get_domain(struct iommufd_device *idev,
*/
if (rc == -EINVAL)
continue;
- goto out_unlock;
+ return rc;
}
hwpt = iommufd_hw_pagetable_alloc(idev->ictx, ioas, idev->dev);
- if (IS_ERR(hwpt)) {
- rc = PTR_ERR(hwpt);
- goto out_unlock;
- }
+ if (IS_ERR(hwpt))
+ return PTR_ERR(hwpt);
hwpt->auto_domain = true;
rc = iommufd_device_do_attach(idev, hwpt);
if (rc)
goto out_abort;
- list_add_tail(&hwpt->hwpt_item, &ioas->hwpt_list);
- mutex_unlock(&ioas->mutex);
iommufd_object_finalize(idev->ictx, &hwpt->obj);
return 0;
out_abort:
iommufd_object_abort_and_destroy(idev->ictx, &hwpt->obj);
-out_unlock:
- mutex_unlock(&ioas->mutex);
return rc;
}
@@ -342,20 +340,20 @@ int iommufd_device_attach(struct iommufd_device *idev, u32 *pt_id)
struct iommufd_hw_pagetable *hwpt =
container_of(pt_obj, struct iommufd_hw_pagetable, obj);
+ mutex_lock(&hwpt->ioas->mutex);
rc = iommufd_device_do_attach(idev, hwpt);
+ mutex_unlock(&hwpt->ioas->mutex);
if (rc)
goto out_put_pt_obj;
-
- mutex_lock(&hwpt->ioas->mutex);
- list_add_tail(&hwpt->hwpt_item, &hwpt->ioas->hwpt_list);
- mutex_unlock(&hwpt->ioas->mutex);
break;
}
case IOMMUFD_OBJ_IOAS: {
struct iommufd_ioas *ioas =
container_of(pt_obj, struct iommufd_ioas, obj);
+ mutex_lock(&ioas->mutex);
rc = iommufd_device_auto_get_domain(idev, ioas);
+ mutex_unlock(&ioas->mutex);
if (rc)
goto out_put_pt_obj;
break;