diff mbox series

[06/18] cxl/region: Refactor attach_target() for autodiscovery

Message ID 167564538227.847146.16305045998592488364.stgit@dwillia2-xfh.jf.intel.com (mailing list archive)
State New
Headers show
Series CXL RAM and the 'Soft Reserved' => 'System RAM' default | expand

Commit Message

Dan Williams Feb. 6, 2023, 1:03 a.m. UTC
Region autodiscovery is the process of kernel creating 'struct
cxl_region' object to represent active CXL memory ranges it finds
already active in hardware when the driver loads. Typically this happens
when platform firmware establishes CXL memory regions and then publishes
them in the memory map. However, this can also happen in the case of
kexec-reboot after the kernel has created regions.

In the autodiscovery case the region creation process starts with a
known endpoint decoder. Refactor attach_target() into a helper that is
suitable to be called from either sysfs, for runtime region creation, or
from cxl_port_probe() after it has enumerated all endpoint decoders.

The cxl_port_probe() context is an async device-core probing context, so
it is not appropriate to allow SIGTERM to interrupt the assembly
process. Refactor attach_target() to take @cxled and @state as arguments
where @state indicates whether waiting from the region rwsem is
interruptible or not.

No behavior change is intended.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/cxl/core/region.c |   47 +++++++++++++++++++++++++++------------------
 1 file changed, 28 insertions(+), 19 deletions(-)

Comments

Jonathan Cameron Feb. 6, 2023, 5:06 p.m. UTC | #1
On Sun, 05 Feb 2023 17:03:02 -0800
Dan Williams <dan.j.williams@intel.com> wrote:

> Region autodiscovery is the process of kernel creating 'struct
> cxl_region' object to represent active CXL memory ranges it finds
> already active in hardware when the driver loads. Typically this happens
> when platform firmware establishes CXL memory regions and then publishes
> them in the memory map. However, this can also happen in the case of
> kexec-reboot after the kernel has created regions.
> 
> In the autodiscovery case the region creation process starts with a
> known endpoint decoder. Refactor attach_target() into a helper that is
> suitable to be called from either sysfs, for runtime region creation, or
> from cxl_port_probe() after it has enumerated all endpoint decoders.
> 
> The cxl_port_probe() context is an async device-core probing context, so
> it is not appropriate to allow SIGTERM to interrupt the assembly
> process. Refactor attach_target() to take @cxled and @state as arguments
> where @state indicates whether waiting from the region rwsem is
> interruptible or not.

As below, I'd have broken this change out as a follow up patch - that
way reviewer could check for strict noop refactor, then look in ioslation
at that case.

I don't care that much though as second patch would only have about 4 lines
of diff.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> 
> No behavior change is intended.
> 
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  drivers/cxl/core/region.c |   47 +++++++++++++++++++++++++++------------------
>  1 file changed, 28 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 8dea49c021b8..97eafdd75675 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -1418,31 +1418,25 @@ void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled)
>  	up_write(&cxl_region_rwsem);
>  }
>  
> -static int attach_target(struct cxl_region *cxlr, const char *decoder, int pos)
> +static int attach_target(struct cxl_region *cxlr,
> +			 struct cxl_endpoint_decoder *cxled, int pos,
> +			 unsigned int state)
>  {
> -	struct device *dev;
> -	int rc;
> -
> -	dev = bus_find_device_by_name(&cxl_bus_type, NULL, decoder);
> -	if (!dev)
> -		return -ENODEV;
> -
> -	if (!is_endpoint_decoder(dev)) {
> -		put_device(dev);
> -		return -EINVAL;
> -	}
> +	int rc = 0;
>  
> -	rc = down_write_killable(&cxl_region_rwsem);
> +	if (state == TASK_INTERRUPTIBLE)
> +		rc = down_write_killable(&cxl_region_rwsem);
> +	else
> +		down_write(&cxl_region_rwsem);

I'd be tempted to do this in two hops for patch readability. First
make the code reorg then follow up with this bit before the use
of it in the next patch.

>  	if (rc)
> -		goto out;
> +		return rc;
> +
>  	down_read(&cxl_dpa_rwsem);
> -	rc = cxl_region_attach(cxlr, to_cxl_endpoint_decoder(dev), pos);
> +	rc = cxl_region_attach(cxlr, cxled, pos);
>  	if (rc == 0)
>  		set_bit(CXL_REGION_F_INCOHERENT, &cxlr->flags);
>  	up_read(&cxl_dpa_rwsem);
>  	up_write(&cxl_region_rwsem);
> -out:
> -	put_device(dev);
>  	return rc;
>  }
>  
> @@ -1480,8 +1474,23 @@ static size_t store_targetN(struct cxl_region *cxlr, const char *buf, int pos,
>  
>  	if (sysfs_streq(buf, "\n"))
>  		rc = detach_target(cxlr, pos);
> -	else
> -		rc = attach_target(cxlr, buf, pos);
> +	else {
> +		struct device *dev;
> +
> +		dev = bus_find_device_by_name(&cxl_bus_type, NULL, buf);
> +		if (!dev)
> +			return -ENODEV;
> +
> +		if (!is_endpoint_decoder(dev)) {
> +			rc = -EINVAL;
> +			goto out;
> +		}
> +
> +		rc = attach_target(cxlr, to_cxl_endpoint_decoder(dev), pos,
> +				   TASK_INTERRUPTIBLE);
> +out:
> +		put_device(dev);
> +	}
>  
>  	if (rc < 0)
>  		return rc;
> 
>
Dan Williams Feb. 6, 2023, 6:48 p.m. UTC | #2
Jonathan Cameron wrote:
> On Sun, 05 Feb 2023 17:03:02 -0800
> Dan Williams <dan.j.williams@intel.com> wrote:
> 
> > Region autodiscovery is the process of kernel creating 'struct
> > cxl_region' object to represent active CXL memory ranges it finds
> > already active in hardware when the driver loads. Typically this happens
> > when platform firmware establishes CXL memory regions and then publishes
> > them in the memory map. However, this can also happen in the case of
> > kexec-reboot after the kernel has created regions.
> > 
> > In the autodiscovery case the region creation process starts with a
> > known endpoint decoder. Refactor attach_target() into a helper that is
> > suitable to be called from either sysfs, for runtime region creation, or
> > from cxl_port_probe() after it has enumerated all endpoint decoders.
> > 
> > The cxl_port_probe() context is an async device-core probing context, so
> > it is not appropriate to allow SIGTERM to interrupt the assembly
> > process. Refactor attach_target() to take @cxled and @state as arguments
> > where @state indicates whether waiting from the region rwsem is
> > interruptible or not.
> 
[..]
> > @@ -1418,31 +1418,25 @@ void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled)
> >  	up_write(&cxl_region_rwsem);
> >  }
> >  
> > -static int attach_target(struct cxl_region *cxlr, const char *decoder, int pos)
> > +static int attach_target(struct cxl_region *cxlr,
> > +			 struct cxl_endpoint_decoder *cxled, int pos,
> > +			 unsigned int state)
> >  {
> > -	struct device *dev;
> > -	int rc;
> > -
> > -	dev = bus_find_device_by_name(&cxl_bus_type, NULL, decoder);
> > -	if (!dev)
> > -		return -ENODEV;
> > -
> > -	if (!is_endpoint_decoder(dev)) {
> > -		put_device(dev);
> > -		return -EINVAL;
> > -	}
> > +	int rc = 0;
> >  
> > -	rc = down_write_killable(&cxl_region_rwsem);
> > +	if (state == TASK_INTERRUPTIBLE)
> > +		rc = down_write_killable(&cxl_region_rwsem);
> > +	else
> > +		down_write(&cxl_region_rwsem);
> 
> I'd be tempted to do this in two hops for patch readability. First
> make the code reorg then follow up with this bit before the use
> of it in the next patch.
> 

Sure.
Ira Weiny Feb. 6, 2023, 7:26 p.m. UTC | #3
Dan Williams wrote:
> Region autodiscovery is the process of kernel creating 'struct
> cxl_region' object to represent active CXL memory ranges it finds
> already active in hardware when the driver loads. Typically this happens
> when platform firmware establishes CXL memory regions and then publishes
> them in the memory map. However, this can also happen in the case of
> kexec-reboot after the kernel has created regions.
> 
> In the autodiscovery case the region creation process starts with a
> known endpoint decoder. Refactor attach_target() into a helper that is
> suitable to be called from either sysfs, for runtime region creation, or
> from cxl_port_probe() after it has enumerated all endpoint decoders.
> 
> The cxl_port_probe() context is an async device-core probing context, so
> it is not appropriate to allow SIGTERM to interrupt the assembly
> process. Refactor attach_target() to take @cxled and @state as arguments
> where @state indicates whether waiting from the region rwsem is
> interruptible or not.
> 
> No behavior change is intended.
> 
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Dave Jiang Feb. 6, 2023, 10:41 p.m. UTC | #4
On 2/5/23 6:03 PM, Dan Williams wrote:
> Region autodiscovery is the process of kernel creating 'struct
> cxl_region' object to represent active CXL memory ranges it finds
> already active in hardware when the driver loads. Typically this happens
> when platform firmware establishes CXL memory regions and then publishes
> them in the memory map. However, this can also happen in the case of
> kexec-reboot after the kernel has created regions.
> 
> In the autodiscovery case the region creation process starts with a
> known endpoint decoder. Refactor attach_target() into a helper that is
> suitable to be called from either sysfs, for runtime region creation, or
> from cxl_port_probe() after it has enumerated all endpoint decoders.
> 
> The cxl_port_probe() context is an async device-core probing context, so
> it is not appropriate to allow SIGTERM to interrupt the assembly
> process. Refactor attach_target() to take @cxled and @state as arguments
> where @state indicates whether waiting from the region rwsem is
> interruptible or not.
> 
> No behavior change is intended.
> 
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>

> ---
>   drivers/cxl/core/region.c |   47 +++++++++++++++++++++++++++------------------
>   1 file changed, 28 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 8dea49c021b8..97eafdd75675 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -1418,31 +1418,25 @@ void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled)
>   	up_write(&cxl_region_rwsem);
>   }
>   
> -static int attach_target(struct cxl_region *cxlr, const char *decoder, int pos)
> +static int attach_target(struct cxl_region *cxlr,
> +			 struct cxl_endpoint_decoder *cxled, int pos,
> +			 unsigned int state)
>   {
> -	struct device *dev;
> -	int rc;
> -
> -	dev = bus_find_device_by_name(&cxl_bus_type, NULL, decoder);
> -	if (!dev)
> -		return -ENODEV;
> -
> -	if (!is_endpoint_decoder(dev)) {
> -		put_device(dev);
> -		return -EINVAL;
> -	}
> +	int rc = 0;
>   
> -	rc = down_write_killable(&cxl_region_rwsem);
> +	if (state == TASK_INTERRUPTIBLE)
> +		rc = down_write_killable(&cxl_region_rwsem);
> +	else
> +		down_write(&cxl_region_rwsem);
>   	if (rc)
> -		goto out;
> +		return rc;
> +
>   	down_read(&cxl_dpa_rwsem);
> -	rc = cxl_region_attach(cxlr, to_cxl_endpoint_decoder(dev), pos);
> +	rc = cxl_region_attach(cxlr, cxled, pos);
>   	if (rc == 0)
>   		set_bit(CXL_REGION_F_INCOHERENT, &cxlr->flags);
>   	up_read(&cxl_dpa_rwsem);
>   	up_write(&cxl_region_rwsem);
> -out:
> -	put_device(dev);
>   	return rc;
>   }
>   
> @@ -1480,8 +1474,23 @@ static size_t store_targetN(struct cxl_region *cxlr, const char *buf, int pos,
>   
>   	if (sysfs_streq(buf, "\n"))
>   		rc = detach_target(cxlr, pos);
> -	else
> -		rc = attach_target(cxlr, buf, pos);
> +	else {
> +		struct device *dev;
> +
> +		dev = bus_find_device_by_name(&cxl_bus_type, NULL, buf);
> +		if (!dev)
> +			return -ENODEV;
> +
> +		if (!is_endpoint_decoder(dev)) {
> +			rc = -EINVAL;
> +			goto out;
> +		}
> +
> +		rc = attach_target(cxlr, to_cxl_endpoint_decoder(dev), pos,
> +				   TASK_INTERRUPTIBLE);
> +out:
> +		put_device(dev);
> +	}
>   
>   	if (rc < 0)
>   		return rc;
>
Verma, Vishal L Feb. 9, 2023, 1:09 a.m. UTC | #5
On Sun, 2023-02-05 at 17:03 -0800, Dan Williams wrote:
> Region autodiscovery is the process of kernel creating 'struct
> cxl_region' object to represent active CXL memory ranges it finds
> already active in hardware when the driver loads. Typically this happens
> when platform firmware establishes CXL memory regions and then publishes
> them in the memory map. However, this can also happen in the case of
> kexec-reboot after the kernel has created regions.
> 
> In the autodiscovery case the region creation process starts with a
> known endpoint decoder. Refactor attach_target() into a helper that is
> suitable to be called from either sysfs, for runtime region creation, or
> from cxl_port_probe() after it has enumerated all endpoint decoders.
> 
> The cxl_port_probe() context is an async device-core probing context, so
> it is not appropriate to allow SIGTERM to interrupt the assembly
> process. Refactor attach_target() to take @cxled and @state as arguments
> where @state indicates whether waiting from the region rwsem is
> interruptible or not.
> 
> No behavior change is intended.
> 
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  drivers/cxl/core/region.c |   47 +++++++++++++++++++++++++++------------------
>  1 file changed, 28 insertions(+), 19 deletions(-)

Looks good,

Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>

> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 8dea49c021b8..97eafdd75675 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -1418,31 +1418,25 @@ void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled)
>         up_write(&cxl_region_rwsem);
>  }
>  
> -static int attach_target(struct cxl_region *cxlr, const char *decoder, int pos)
> +static int attach_target(struct cxl_region *cxlr,
> +                        struct cxl_endpoint_decoder *cxled, int pos,
> +                        unsigned int state)
>  {
> -       struct device *dev;
> -       int rc;
> -
> -       dev = bus_find_device_by_name(&cxl_bus_type, NULL, decoder);
> -       if (!dev)
> -               return -ENODEV;
> -
> -       if (!is_endpoint_decoder(dev)) {
> -               put_device(dev);
> -               return -EINVAL;
> -       }
> +       int rc = 0;
>  
> -       rc = down_write_killable(&cxl_region_rwsem);
> +       if (state == TASK_INTERRUPTIBLE)
> +               rc = down_write_killable(&cxl_region_rwsem);
> +       else
> +               down_write(&cxl_region_rwsem);
>         if (rc)
> -               goto out;
> +               return rc;
> +
>         down_read(&cxl_dpa_rwsem);
> -       rc = cxl_region_attach(cxlr, to_cxl_endpoint_decoder(dev), pos);
> +       rc = cxl_region_attach(cxlr, cxled, pos);
>         if (rc == 0)
>                 set_bit(CXL_REGION_F_INCOHERENT, &cxlr->flags);
>         up_read(&cxl_dpa_rwsem);
>         up_write(&cxl_region_rwsem);
> -out:
> -       put_device(dev);
>         return rc;
>  }
>  
> @@ -1480,8 +1474,23 @@ static size_t store_targetN(struct cxl_region *cxlr, const char *buf, int pos,
>  
>         if (sysfs_streq(buf, "\n"))
>                 rc = detach_target(cxlr, pos);
> -       else
> -               rc = attach_target(cxlr, buf, pos);
> +       else {
> +               struct device *dev;
> +
> +               dev = bus_find_device_by_name(&cxl_bus_type, NULL, buf);
> +               if (!dev)
> +                       return -ENODEV;
> +
> +               if (!is_endpoint_decoder(dev)) {
> +                       rc = -EINVAL;
> +                       goto out;
> +               }
> +
> +               rc = attach_target(cxlr, to_cxl_endpoint_decoder(dev), pos,
> +                                  TASK_INTERRUPTIBLE);
> +out:
> +               put_device(dev);
> +       }
>  
>         if (rc < 0)
>                 return rc;
>
diff mbox series

Patch

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 8dea49c021b8..97eafdd75675 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -1418,31 +1418,25 @@  void cxl_decoder_kill_region(struct cxl_endpoint_decoder *cxled)
 	up_write(&cxl_region_rwsem);
 }
 
-static int attach_target(struct cxl_region *cxlr, const char *decoder, int pos)
+static int attach_target(struct cxl_region *cxlr,
+			 struct cxl_endpoint_decoder *cxled, int pos,
+			 unsigned int state)
 {
-	struct device *dev;
-	int rc;
-
-	dev = bus_find_device_by_name(&cxl_bus_type, NULL, decoder);
-	if (!dev)
-		return -ENODEV;
-
-	if (!is_endpoint_decoder(dev)) {
-		put_device(dev);
-		return -EINVAL;
-	}
+	int rc = 0;
 
-	rc = down_write_killable(&cxl_region_rwsem);
+	if (state == TASK_INTERRUPTIBLE)
+		rc = down_write_killable(&cxl_region_rwsem);
+	else
+		down_write(&cxl_region_rwsem);
 	if (rc)
-		goto out;
+		return rc;
+
 	down_read(&cxl_dpa_rwsem);
-	rc = cxl_region_attach(cxlr, to_cxl_endpoint_decoder(dev), pos);
+	rc = cxl_region_attach(cxlr, cxled, pos);
 	if (rc == 0)
 		set_bit(CXL_REGION_F_INCOHERENT, &cxlr->flags);
 	up_read(&cxl_dpa_rwsem);
 	up_write(&cxl_region_rwsem);
-out:
-	put_device(dev);
 	return rc;
 }
 
@@ -1480,8 +1474,23 @@  static size_t store_targetN(struct cxl_region *cxlr, const char *buf, int pos,
 
 	if (sysfs_streq(buf, "\n"))
 		rc = detach_target(cxlr, pos);
-	else
-		rc = attach_target(cxlr, buf, pos);
+	else {
+		struct device *dev;
+
+		dev = bus_find_device_by_name(&cxl_bus_type, NULL, buf);
+		if (!dev)
+			return -ENODEV;
+
+		if (!is_endpoint_decoder(dev)) {
+			rc = -EINVAL;
+			goto out;
+		}
+
+		rc = attach_target(cxlr, to_cxl_endpoint_decoder(dev), pos,
+				   TASK_INTERRUPTIBLE);
+out:
+		put_device(dev);
+	}
 
 	if (rc < 0)
 		return rc;