2022-03-30 10:58:55

by Mika Penttilä

Subject: [PATCH v6] mm/hmm/test: use char dev with struct device to get device node

From: Mika Penttilä <[email protected]>

HMM selftests use an in-kernel pseudo device to emulate device private
memory. The pseudo device registers a major device range for two pseudo
device instances. User space has a script that reads /proc/devices in
order to find the assigned major number, and sends that to mknod(1),
once for each node.

Change this to properly use cdev and struct device APIs.

Delete the /proc/devices parsing from the user-space test script, now
that it is unnecessary.

Also, deleted an unused field in struct dmirror_device: devmem.

Signed-off-by: Mika Penttilä <[email protected]>
Reviewed-by: John Hubbard <[email protected]>
Cc: Alistair Popple <[email protected]>
Cc: Ralph Campbell <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Vlastimil Babka <[email protected]>
---
v6:
- remove device names array
- check return value of dev_set_name()
v5:
- fix whitespace
. delete unused structure field
v4:
- fix commit log
v3:
- use cdev_device_add() instead of miscdevice
v2:
- Cleanups per review comments from John Hubbard
- Added Tested-by and Ccs


lib/test_hmm.c | 13 ++++++++++---
tools/testing/selftests/vm/test_hmm.sh | 6 ------
2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index cfe632047839..7d1f98bc9c9a 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -86,7 +86,7 @@ struct dmirror_chunk {
*/
struct dmirror_device {
struct cdev cdevice;
- struct hmm_devmem *devmem;
+ struct device device;

unsigned int devmem_capacity;
unsigned int devmem_count;
@@ -1227,7 +1227,14 @@ static int dmirror_device_init(struct dmirror_device *mdevice, int id)

cdev_init(&mdevice->cdevice, &dmirror_fops);
mdevice->cdevice.owner = THIS_MODULE;
- ret = cdev_add(&mdevice->cdevice, dev, 1);
+ device_initialize(&mdevice->device);
+ mdevice->device.devt = dev;
+
+ ret = dev_set_name(&mdevice->device, "hmm_dmirror%u", id);
+ if (ret)
+ return ret;
+
+ ret = cdev_device_add(&mdevice->cdevice, &mdevice->device);
if (ret)
return ret;

@@ -1254,7 +1261,7 @@ static void dmirror_device_remove(struct dmirror_device *mdevice)
kfree(mdevice->devmem_chunks);
}

- cdev_del(&mdevice->cdevice);
+ cdev_device_del(&mdevice->cdevice, &mdevice->device);
}

static int __init hmm_dmirror_init(void)
diff --git a/tools/testing/selftests/vm/test_hmm.sh b/tools/testing/selftests/vm/test_hmm.sh
index 0647b525a625..69f5889f8575 100755
--- a/tools/testing/selftests/vm/test_hmm.sh
+++ b/tools/testing/selftests/vm/test_hmm.sh
@@ -41,17 +41,11 @@ check_test_requirements()
load_driver()
{
modprobe $DRIVER > /dev/null 2>&1
- if [ $? == 0 ]; then
- major=$(awk "\$2==\"HMM_DMIRROR\" {print \$1}" /proc/devices)
- mknod /dev/hmm_dmirror0 c $major 0
- mknod /dev/hmm_dmirror1 c $major 1
- fi
}

unload_driver()
{
modprobe -r $DRIVER > /dev/null 2>&1
- rm -f /dev/hmm_dmirror?
}

run_smoke()
--
2.17.1

2022-03-30 20:50:30

by Christoph Hellwig

Subject: Re: [PATCH v6] mm/hmm/test: use char dev with struct device to get device node

Looks good:

Reviewed-by: Christoph Hellwig <[email protected]>

2022-03-30 21:44:20

by Jason Gunthorpe

Subject: Re: [PATCH v6] mm/hmm/test: use char dev with struct device to get device node

On Wed, Mar 30, 2022 at 03:47:25AM +0300, [email protected] wrote:
> From: Mika Penttilä <[email protected]>
>
> HMM selftests use an in-kernel pseudo device to emulate device private
> memory. The pseudo device registers a major device range for two pseudo
> device instances. User space has a script that reads /proc/devices in
> order to find the assigned major number, and sends that to mknod(1),
> once for each node.
>
> Change this to properly use cdev and struct device APIs.
>
> Delete the /proc/devices parsing from the user-space test script, now
> that it is unnecessary.
>
> Also, deleted an unused field in struct dmirror_device: devmem.
>
> Signed-off-by: Mika Penttilä <[email protected]>
> Reviewed-by: John Hubbard <[email protected]>
> Cc: Alistair Popple <[email protected]>
> Cc: Ralph Campbell <[email protected]>
> Cc: Jason Gunthorpe <[email protected]>
> Cc: Vlastimil Babka <[email protected]>
> ---
> v6:
> - remove device names array
> - check return value of dev_set_name()
> v5:
> - fix whitespace
> . delete unused structure field
> v4:
> - fix commit log
> v3:
> - use cdev_device_add() instead of miscdevice
> v2:
> - Cleanups per review comments from John Hubbard
> - Added Tested-by and Ccs
>
>
> lib/test_hmm.c | 13 ++++++++++---
> tools/testing/selftests/vm/test_hmm.sh | 6 ------
> 2 files changed, 10 insertions(+), 9 deletions(-)

Reviewed-by: Jason Gunthorpe <[email protected]>

Jason