Re: [PATCH v7 01/14] dmaengine: idxd: add wq driver name support for accel-config user tool

Fenghua Yu
2023-07-11T17:49:50Z

Hi, Tom,

On 7/10/23 12:06, Tom Zanussi wrote:
> From: Dave Jiang <dave.jiang@intel.com>
>
> With the possibility of multiple wq drivers that can be bound to the wq,
> the user config tool accel-config needs a way to know which wq driver to
> bind to the wq. Introduce per wq driver_name sysfs attribute where the user
> can indicate the driver to be bound to the wq. This allows accel-config to
> just bind to the driver using wq->driver_name.
>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
> ---
> .../ABI/stable/sysfs-driver-dma-idxd | 6 ++++
> drivers/dma/idxd/cdev.c | 7 +++++
> drivers/dma/idxd/dma.c | 6 ++++
> drivers/dma/idxd/idxd.h | 9 ++++++
> drivers/dma/idxd/sysfs.c | 28 +++++++++++++++++++
> include/uapi/linux/idxd.h | 1 +
> 6 files changed, 57 insertions(+)
>
> diff --git a/Documentation/ABI/stable/sysfs-driver-dma-idxd b/Documentation/ABI/stable/sysfs-driver-dma-idxd
> index 534b7a3d59fc..0e577209bee2 100644
> --- a/Documentation/ABI/stable/sysfs-driver-dma-idxd
> +++ b/Documentation/ABI/stable/sysfs-driver-dma-idxd
> @@ -270,6 +270,12 @@ Description: Shows the operation capability bits displayed in bitmap format
> correlates to the operations allowed. It's visible only
> on platforms that support the capability.
>
> +What: /sys/bus/dsa/devices/wq<m>.<n>/driver_name
> +Date: Mar 27, 2023
> +KernelVersion: 6.6.0
> +Contact: dmaengine@vger.kernel.org
> +Description: Name of driver to be bounded to the wq.
> +
> What: /sys/bus/dsa/devices/engine<m>.<n>/group_id
> Date: Oct 25, 2019
> KernelVersion: 5.6.0
> diff --git a/drivers/dma/idxd/cdev.c b/drivers/dma/idxd/cdev.c
> index ecbf67c2ad2b..b1ecfb71d95e 100644
> --- a/drivers/dma/idxd/cdev.c
> +++ b/drivers/dma/idxd/cdev.c
> @@ -510,6 +510,7 @@ void idxd_wq_del_cdev(struct idxd_wq *wq)
>
> static int idxd_user_drv_probe(struct idxd_dev *idxd_dev)
> {
> + struct device *dev = &idxd_dev->conf_dev;
> struct idxd_wq *wq = idxd_dev_to_wq(idxd_dev);
> struct idxd_device *idxd = wq->idxd;
> int rc;
> @@ -537,6 +538,12 @@ static int idxd_user_drv_probe(struct idxd_dev *idxd_dev)
>
> mutex_lock(&wq->wq_lock);
>
> + if (!idxd_wq_driver_name_match(wq, dev)) {
> + idxd->cmd_status = IDXD_SCMD_WQ_NO_DRV_NAME;
> + rc = -ENODEV;
> + goto wq_err;
> + }
> +
> wq->wq = create_workqueue(dev_name(wq_confdev(wq)));
> if (!wq->wq) {
> rc = -ENOMEM;
> diff --git a/drivers/dma/idxd/dma.c b/drivers/dma/idxd/dma.c
> index eb35ca313684..8bb7e7ff8d6a 100644
> --- a/drivers/dma/idxd/dma.c
> +++ b/drivers/dma/idxd/dma.c
> @@ -305,6 +305,12 @@ static int idxd_dmaengine_drv_probe(struct idxd_dev *idxd_dev)
> return -ENXIO;
>
> mutex_lock(&wq->wq_lock);
> + if (!idxd_wq_driver_name_match(wq, dev)) {
> + idxd->cmd_status = IDXD_SCMD_WQ_NO_DRV_NAME;
> + rc = -ENODEV;
> + goto err;
> + }
> +
> wq->type = IDXD_WQT_KERNEL;
>
> rc = drv_enable_wq(wq);
> diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
> index 5428a2e1b1ec..c62c78e1c9fa 100644
> --- a/drivers/dma/idxd/idxd.h
> +++ b/drivers/dma/idxd/idxd.h
> @@ -159,6 +159,8 @@ struct idxd_cdev {
> int minor;
> };
>
> +#define DRIVER_NAME_SIZE 128
> +
> #define IDXD_ALLOCATED_BATCH_SIZE 128U
> #define WQ_NAME_SIZE 1024
> #define WQ_TYPE_SIZE 10
> @@ -227,6 +229,8 @@ struct idxd_wq {
> /* Lock to protect upasid_xa access. */
> struct mutex uc_lock;
> struct xarray upasid_xa;
> +
> + char driver_name[DRIVER_NAME_SIZE + 1];
> };
>
> struct idxd_engine {
> @@ -637,6 +641,11 @@ static inline void idxd_wqcfg_set_max_batch_shift(int idxd_type, union wqcfg *wq
> wqcfg->max_batch_shift = max_batch_shift;
> }
>
> +static inline int idxd_wq_driver_name_match(struct idxd_wq *wq, struct device *dev)
> +{
> + return (strncmp(wq->driver_name, dev->driver->name, strlen(dev->driver->name)) == 0);
> +}
> +
> int __must_check __idxd_driver_register(struct idxd_device_driver *idxd_drv,
> struct module *module, const char *mod_name);
> #define idxd_driver_register(driver) \
> diff --git a/drivers/dma/idxd/sysfs.c b/drivers/dma/idxd/sysfs.c
> index 293739ac5596..6caad044f506 100644
> --- a/drivers/dma/idxd/sysfs.c
> +++ b/drivers/dma/idxd/sysfs.c
> @@ -1266,6 +1266,33 @@ static ssize_t wq_op_config_store(struct device *dev, struct device_attribute *a
> static struct device_attribute dev_attr_wq_op_config =
> __ATTR(op_config, 0644, wq_op_config_show, wq_op_config_store);
>
> +static ssize_t wq_driver_name_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> + struct idxd_wq *wq = confdev_to_wq(dev);
> +
> + return sysfs_emit(buf, "%s\n", wq->driver_name);
> +}
> +
> +static ssize_t wq_driver_name_store(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct idxd_wq *wq = confdev_to_wq(dev);
> +
> + if (wq->state != IDXD_WQ_DISABLED)
> + return -EPERM;
> +
> + if (strlen(buf) > DRIVER_NAME_SIZE || strlen(buf) == 0)
> + return -EINVAL;
> +
> + memset(wq->driver_name, 0, DRIVER_NAME_SIZE + 1);
> + strncpy(wq->driver_name, buf, DRIVER_NAME_SIZE);
> + strreplace(wq->name, '\n', '\0');

If user inputs "dmaengine " (with the trailing white spaces), the
trailing white spaces will be copied to wq->driver_name. Later driver
name match will always fail.

A better way is using strim() to remove the trailing white spaces before
copying the buffer to wq->driver_name. So wq->driver_name is "dmaengine"
(without the trailing white spaces).

Thanks.

-Fenghua