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

[Tom Zanussi <tom.zanussi@linux.intel.com>]

Hi Fenghua,

On Tue, 2023-07-11 at 10:49 -0700, Fenghua Yu wrote:
> 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).
> 

Yes, good point, I'll add that.  Thanks for pointing that out!

Tom


> Thanks.
> 
> -Fenghua