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

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Hi, Tom,

On 7/10/23 12:06, Tom Zanussi wrote:
From: Dave Jiang <dave.jiang@xxxxxxxxx>

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@xxxxxxxxx>
Signed-off-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
---
  .../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@xxxxxxxxxxxxxxx
+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



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