[PATCH] cxl/acpi: Fix load failures due to single window creation failure

[PATCH] cxl/acpi: Fix load failures due to single window creation failure

[Dan Williams]

The expectation is that cxl_parse_cfwms() continues in the face the of
failure as evidenced by code like:

    cxlrd = cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);
    if (IS_ERR(cxlrd))
    	return 0;

There are other error paths in that function which mistakenly follow
idiomatic expectations and return an error when they should not. Most of
those mistakes are innocuous checks that hardly ever fail in practice.
However, a recent change succeed in making the implementation more
fragile by applying an idiomatic, but still wrong "fix" [1]. In this
failure case the kernel reports:

    cxl root0: Failed to populate active decoder targets
    cxl_acpi ACPI0017:00: Failed to add decode range: [mem 0x00000000-0x7fffffff flags 0x200]

...which is a real issue with that one window (to be fixed separately),
but ends up failing the entirety of cxl_acpi_probe().

Undo that recent breakage while also removing the confusion about
ignoring errors. Update all exits paths to return an error per typical
expectations and let an outer wrapper function handle dropping the
error.

Fixes: 91019b5bc7c2 ("cxl/acpi: Return 'rc' instead of '0' in cxl_parse_cfmws()") [1]
Cc: <stable@vger.kernel.org>
Cc: Breno Leitao <leitao@debian.org>
Cc: Alison Schofield <alison.schofield@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/cxl/acpi.c |   45 +++++++++++++++++++++++++++------------------
 1 file changed, 27 insertions(+), 18 deletions(-)

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index dcf2b39e1048..53d2dff0c7a3 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -316,31 +316,27 @@ static const struct cxl_root_ops acpi_root_ops = {
 	.qos_class = cxl_acpi_qos_class,
 };
 
-static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
-			   const unsigned long end)
+static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
+			     struct cxl_cfmws_context *ctx)
 {
 	int target_map[CXL_DECODER_MAX_INTERLEAVE];
-	struct cxl_cfmws_context *ctx = arg;
 	struct cxl_port *root_port = ctx->root_port;
 	struct resource *cxl_res = ctx->cxl_res;
 	struct cxl_cxims_context cxims_ctx;
 	struct cxl_root_decoder *cxlrd;
 	struct device *dev = ctx->dev;
-	struct acpi_cedt_cfmws *cfmws;
 	cxl_calc_hb_fn cxl_calc_hb;
 	struct cxl_decoder *cxld;
 	unsigned int ways, i, ig;
 	struct resource *res;
 	int rc;
 
-	cfmws = (struct acpi_cedt_cfmws *) header;
-
 	rc = cxl_acpi_cfmws_verify(dev, cfmws);
 	if (rc) {
 		dev_err(dev, "CFMWS range %#llx-%#llx not registered\n",
 			cfmws->base_hpa,
 			cfmws->base_hpa + cfmws->window_size - 1);
-		return 0;
+		return rc;
 	}
 
 	rc = eiw_to_ways(cfmws->interleave_ways, &ways);
@@ -376,7 +372,7 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
 
 	cxlrd = cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);
 	if (IS_ERR(cxlrd))
-		return 0;
+		return PTR_ERR(cxlrd);
 
 	cxld = &cxlrd->cxlsd.cxld;
 	cxld->flags = cfmws_to_decoder_flags(cfmws->restrictions);
@@ -420,16 +416,7 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
 		put_device(&cxld->dev);
 	else
 		rc = cxl_decoder_autoremove(dev, cxld);
-	if (rc) {
-		dev_err(dev, "Failed to add decode range: %pr", res);
-		return rc;
-	}
-	dev_dbg(dev, "add: %s node: %d range [%#llx - %#llx]\n",
-		dev_name(&cxld->dev),
-		phys_to_target_node(cxld->hpa_range.start),
-		cxld->hpa_range.start, cxld->hpa_range.end);
-
-	return 0;
+	return rc;
 
 err_insert:
 	kfree(res->name);
@@ -438,6 +425,28 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
 	return -ENOMEM;
 }
 
+static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
+			   const unsigned long end)
+{
+	struct acpi_cedt_cfmws *cfmws = (struct acpi_cedt_cfmws *)header;
+	struct cxl_cfmws_context *ctx = arg;
+	struct device *dev = ctx->dev;
+	int rc;
+
+	dev_dbg(dev, "decode range: node: %d range [%#llx - %#llx]\n",
+		phys_to_target_node(cfmws->base_hpa), cfmws->base_hpa,
+		cfmws->base_hpa + cfmws->window_size - 1);
+	rc = __cxl_parse_cfmws(cfmws, ctx);
+	if (rc)
+		dev_err(dev,
+			"Failed to add decode range: [%#llx - %#llx] (%d)\n",
+			cfmws->base_hpa,
+			cfmws->base_hpa + cfmws->window_size - 1, rc);
+
+	/* never fail cxl_acpi load for a single window failure */
+	return 0;
+}
+
 __mock struct acpi_device *to_cxl_host_bridge(struct device *host,
 					      struct device *dev)
 {

Re: [PATCH] cxl/acpi: Fix load failures due to single window creation failure

[Jonathan Cameron]

On Sat, 17 Feb 2024 12:29:32 -0800
Dan Williams <dan.j.williams@intel.com> wrote:

> The expectation is that cxl_parse_cfwms() continues in the face the of
> failure as evidenced by code like:
> 
>     cxlrd = cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);
>     if (IS_ERR(cxlrd))
>     	return 0;
> 
> There are other error paths in that function which mistakenly follow
> idiomatic expectations and return an error when they should not. Most of
> those mistakes are innocuous checks that hardly ever fail in practice.
> However, a recent change succeed in making the implementation more
> fragile by applying an idiomatic, but still wrong "fix" [1]. In this
> failure case the kernel reports:
> 
>     cxl root0: Failed to populate active decoder targets
>     cxl_acpi ACPI0017:00: Failed to add decode range: [mem 0x00000000-0x7fffffff flags 0x200]
> 
> ...which is a real issue with that one window (to be fixed separately),
> but ends up failing the entirety of cxl_acpi_probe().
> 
> Undo that recent breakage while also removing the confusion about
> ignoring errors. Update all exits paths to return an error per typical
> expectations and let an outer wrapper function handle dropping the
> error.
> 
> Fixes: 91019b5bc7c2 ("cxl/acpi: Return 'rc' instead of '0' in cxl_parse_cfmws()") [1]
> Cc: <stable@vger.kernel.org>
> Cc: Breno Leitao <leitao@debian.org>
> Cc: Alison Schofield <alison.schofield@intel.com>
> Cc: Vishal Verma <vishal.l.verma@intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

General idea makes a lot of sense to me.

A few comments on specific implementation inline

> ---
>  drivers/cxl/acpi.c |   45 +++++++++++++++++++++++++++------------------
>  1 file changed, 27 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> index dcf2b39e1048..53d2dff0c7a3 100644
> --- a/drivers/cxl/acpi.c
> +++ b/drivers/cxl/acpi.c
> @@ -316,31 +316,27 @@ static const struct cxl_root_ops acpi_root_ops = {
>  	.qos_class = cxl_acpi_qos_class,
>  };
>  
> -static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> -			   const unsigned long end)
> +static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
> +			     struct cxl_cfmws_context *ctx)
>  {
>  	int target_map[CXL_DECODER_MAX_INTERLEAVE];
> -	struct cxl_cfmws_context *ctx = arg;
>  	struct cxl_port *root_port = ctx->root_port;
>  	struct resource *cxl_res = ctx->cxl_res;
>  	struct cxl_cxims_context cxims_ctx;
>  	struct cxl_root_decoder *cxlrd;
>  	struct device *dev = ctx->dev;
> -	struct acpi_cedt_cfmws *cfmws;
>  	cxl_calc_hb_fn cxl_calc_hb;
>  	struct cxl_decoder *cxld;
>  	unsigned int ways, i, ig;
>  	struct resource *res;
>  	int rc;
>  
> -	cfmws = (struct acpi_cedt_cfmws *) header;
> -
>  	rc = cxl_acpi_cfmws_verify(dev, cfmws);
>  	if (rc) {
>  		dev_err(dev, "CFMWS range %#llx-%#llx not registered\n",
>  			cfmws->base_hpa,
>  			cfmws->base_hpa + cfmws->window_size - 1);

Why keep this error print?

> -		return 0;
> +		return rc;
>  	}
>  
>  	rc = eiw_to_ways(cfmws->interleave_ways, &ways);
> @@ -376,7 +372,7 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
>  
>  	cxlrd = cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);
>  	if (IS_ERR(cxlrd))
> -		return 0;
> +		return PTR_ERR(cxlrd);
>  
>  	cxld = &cxlrd->cxlsd.cxld;
>  	cxld->flags = cfmws_to_decoder_flags(cfmws->restrictions);
> @@ -420,16 +416,7 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
>  		put_device(&cxld->dev);
>  	else
>  		rc = cxl_decoder_autoremove(dev, cxld);
> -	if (rc) {
> -		dev_err(dev, "Failed to add decode range: %pr", res);
> -		return rc;

As no longer sharing this message. Might be neater to have this lot as
	rc = cxl_decoder_add(cxld, target_map);
err_xormap:
	if (rc) {
		put_device(&cxld->dev);
		return rc;
	}

	return cxl_decoder_autoremove(dev, cxld);

or a second error exit path.

	rc = cxl_decoder_add(cxld, target_map);
	if (rc)
		goto err_put_devie;

	return cxl_decoder_autoremove(dev, cxld;

err_put_device;
	put_device(&cxld->dev);
	return rc;

err_insert:
	kfree(res->name); ...


> -	}
> -	dev_dbg(dev, "add: %s node: %d range [%#llx - %#llx]\n",
> -		dev_name(&cxld->dev),
> -		phys_to_target_node(cxld->hpa_range.start),
> -		cxld->hpa_range.start, cxld->hpa_range.end);
> -
> -	return 0;
> +	return rc;
>  
>  err_insert:
>  	kfree(res->name);
> @@ -438,6 +425,28 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
>  	return -ENOMEM;
>  }
>  
> +static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> +			   const unsigned long end)
> +{
> +	struct acpi_cedt_cfmws *cfmws = (struct acpi_cedt_cfmws *)header;
> +	struct cxl_cfmws_context *ctx = arg;
> +	struct device *dev = ctx->dev;
> +	int rc;
> +
> +	dev_dbg(dev, "decode range: node: %d range [%#llx - %#llx]\n",
> +		phys_to_target_node(cfmws->base_hpa), cfmws->base_hpa,
> +		cfmws->base_hpa + cfmws->window_size - 1);

Could maybe put this in an else below?

> +	rc = __cxl_parse_cfmws(cfmws, ctx);
> +	if (rc)
> +		dev_err(dev,
> +			"Failed to add decode range: [%#llx - %#llx] (%d)\n",
> +			cfmws->base_hpa,
> +			cfmws->base_hpa + cfmws->window_size - 1, rc);
> +
else 
	dev_dbg();

so we only give the dbg version on success?

> +	/* never fail cxl_acpi load for a single window failure */
> +	return 0;
> +}
> +
>  __mock struct acpi_device *to_cxl_host_bridge(struct device *host,
>  					      struct device *dev)
>  {
> 
> 

Re: [PATCH] cxl/acpi: Fix load failures due to single window creation failure

[Dan Williams]

Jonathan Cameron wrote:
> On Sat, 17 Feb 2024 12:29:32 -0800
> Dan Williams <dan.j.williams@intel.com> wrote:
> 
> > The expectation is that cxl_parse_cfwms() continues in the face the of
> > failure as evidenced by code like:
> > 
> >     cxlrd = cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);
> >     if (IS_ERR(cxlrd))
> >     	return 0;
> > 
> > There are other error paths in that function which mistakenly follow
> > idiomatic expectations and return an error when they should not. Most of
> > those mistakes are innocuous checks that hardly ever fail in practice.
> > However, a recent change succeed in making the implementation more
> > fragile by applying an idiomatic, but still wrong "fix" [1]. In this
> > failure case the kernel reports:
> > 
> >     cxl root0: Failed to populate active decoder targets
> >     cxl_acpi ACPI0017:00: Failed to add decode range: [mem 0x00000000-0x7fffffff flags 0x200]
> > 
> > ...which is a real issue with that one window (to be fixed separately),
> > but ends up failing the entirety of cxl_acpi_probe().
> > 
> > Undo that recent breakage while also removing the confusion about
> > ignoring errors. Update all exits paths to return an error per typical
> > expectations and let an outer wrapper function handle dropping the
> > error.
> > 
> > Fixes: 91019b5bc7c2 ("cxl/acpi: Return 'rc' instead of '0' in cxl_parse_cfmws()") [1]
> > Cc: <stable@vger.kernel.org>
> > Cc: Breno Leitao <leitao@debian.org>
> > Cc: Alison Schofield <alison.schofield@intel.com>
> > Cc: Vishal Verma <vishal.l.verma@intel.com>
> > Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> 
> General idea makes a lot of sense to me.
> 
> A few comments on specific implementation inline
> 
> > ---
> >  drivers/cxl/acpi.c |   45 +++++++++++++++++++++++++++------------------
> >  1 file changed, 27 insertions(+), 18 deletions(-)
> > 
> > diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> > index dcf2b39e1048..53d2dff0c7a3 100644
> > --- a/drivers/cxl/acpi.c
> > +++ b/drivers/cxl/acpi.c
> > @@ -316,31 +316,27 @@ static const struct cxl_root_ops acpi_root_ops = {
> >  	.qos_class = cxl_acpi_qos_class,
> >  };
> >  
> > -static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> > -			   const unsigned long end)
> > +static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
> > +			     struct cxl_cfmws_context *ctx)
> >  {
> >  	int target_map[CXL_DECODER_MAX_INTERLEAVE];
> > -	struct cxl_cfmws_context *ctx = arg;
> >  	struct cxl_port *root_port = ctx->root_port;
> >  	struct resource *cxl_res = ctx->cxl_res;
> >  	struct cxl_cxims_context cxims_ctx;
> >  	struct cxl_root_decoder *cxlrd;
> >  	struct device *dev = ctx->dev;
> > -	struct acpi_cedt_cfmws *cfmws;
> >  	cxl_calc_hb_fn cxl_calc_hb;
> >  	struct cxl_decoder *cxld;
> >  	unsigned int ways, i, ig;
> >  	struct resource *res;
> >  	int rc;
> >  
> > -	cfmws = (struct acpi_cedt_cfmws *) header;
> > -
> >  	rc = cxl_acpi_cfmws_verify(dev, cfmws);
> >  	if (rc) {
> >  		dev_err(dev, "CFMWS range %#llx-%#llx not registered\n",
> >  			cfmws->base_hpa,
> >  			cfmws->base_hpa + cfmws->window_size - 1);
> 
> Why keep this error print?

True, that can go.

> > -		return 0;
> > +		return rc;
> >  	}
> >  
> >  	rc = eiw_to_ways(cfmws->interleave_ways, &ways);
> > @@ -376,7 +372,7 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> >  
> >  	cxlrd = cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);
> >  	if (IS_ERR(cxlrd))
> > -		return 0;
> > +		return PTR_ERR(cxlrd);
> >  
> >  	cxld = &cxlrd->cxlsd.cxld;
> >  	cxld->flags = cfmws_to_decoder_flags(cfmws->restrictions);
> > @@ -420,16 +416,7 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> >  		put_device(&cxld->dev);
> >  	else
> >  		rc = cxl_decoder_autoremove(dev, cxld);
> > -	if (rc) {
> > -		dev_err(dev, "Failed to add decode range: %pr", res);
> > -		return rc;
> 
> As no longer sharing this message. Might be neater to have this lot as
> 	rc = cxl_decoder_add(cxld, target_map);
> err_xormap:
> 	if (rc) {
> 		put_device(&cxld->dev);
> 		return rc;
> 	}
> 
> 	return cxl_decoder_autoremove(dev, cxld);
> 
> or a second error exit path.
> 
> 	rc = cxl_decoder_add(cxld, target_map);
> 	if (rc)
> 		goto err_put_devie;
> 
> 	return cxl_decoder_autoremove(dev, cxld;
> 
> err_put_device;
> 	put_device(&cxld->dev);
> 	return rc;
> 
> err_insert:
> 	kfree(res->name); ...

True, there's enough here to do an even deeper cleanup... below.

> 
> 
> > -	}
> > -	dev_dbg(dev, "add: %s node: %d range [%#llx - %#llx]\n",
> > -		dev_name(&cxld->dev),
> > -		phys_to_target_node(cxld->hpa_range.start),
> > -		cxld->hpa_range.start, cxld->hpa_range.end);
> > -
> > -	return 0;
> > +	return rc;
> >  
> >  err_insert:
> >  	kfree(res->name);
> > @@ -438,6 +425,28 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> >  	return -ENOMEM;
> >  }
> >  
> > +static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> > +			   const unsigned long end)
> > +{
> > +	struct acpi_cedt_cfmws *cfmws = (struct acpi_cedt_cfmws *)header;
> > +	struct cxl_cfmws_context *ctx = arg;
> > +	struct device *dev = ctx->dev;
> > +	int rc;
> > +
> > +	dev_dbg(dev, "decode range: node: %d range [%#llx - %#llx]\n",
> > +		phys_to_target_node(cfmws->base_hpa), cfmws->base_hpa,
> > +		cfmws->base_hpa + cfmws->window_size - 1);
> 
> Could maybe put this in an else below?
> 
> > +	rc = __cxl_parse_cfmws(cfmws, ctx);
> > +	if (rc)
> > +		dev_err(dev,
> > +			"Failed to add decode range: [%#llx - %#llx] (%d)\n",
> > +			cfmws->base_hpa,
> > +			cfmws->base_hpa + cfmws->window_size - 1, rc);
> > +
> else 
> 	dev_dbg();
> 
> so we only give the dbg version on success?

Yeah, I will switch to this since the previous state was also skipping
the debug messages on success.

Follow-on cleanup:

-- 8< --
From e30c267c0b69d5e4531d8f65ec86e4fa32d72340 Mon Sep 17 00:00:00 2001
From: Dan Williams <dan.j.williams@intel.com>
Date: Tue, 20 Feb 2024 22:44:34 -0800
Subject: [PATCH] cxl/acpi: Cleanup __cxl_parse_cfmws() error exits

As a follow on to the recent rework of __cxl_parse_cfmws() to always
return errors, use cleanup.h helpers to remove goto and other cleanups
now that logging is moved to the cxl_parse_cfmws() wrapper.

Reported-by: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
Closes: http://lore.kernel.org/r/20240219124041.00002bda@Huawei.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/cxl/acpi.c | 45 +++++++++++++++++++--------------------------
 1 file changed, 19 insertions(+), 26 deletions(-)

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index 1a3e6aafbdcc..b1ea2d152c65 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -319,25 +319,23 @@ static const struct cxl_root_ops acpi_root_ops = {
 static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 			     struct cxl_cfmws_context *ctx)
 {
+	struct device *cxld_dev __free(put_device) = NULL;
 	int target_map[CXL_DECODER_MAX_INTERLEAVE];
 	struct cxl_port *root_port = ctx->root_port;
+	struct resource *res __free(kfree) = NULL;
 	struct resource *cxl_res = ctx->cxl_res;
+	const char *name __free(kfree) = NULL;
 	struct cxl_cxims_context cxims_ctx;
 	struct cxl_root_decoder *cxlrd;
 	struct device *dev = ctx->dev;
 	cxl_calc_hb_fn cxl_calc_hb;
 	struct cxl_decoder *cxld;
 	unsigned int ways, i, ig;
-	struct resource *res;
 	int rc;
 
 	rc = cxl_acpi_cfmws_verify(dev, cfmws);
-	if (rc) {
-		dev_err(dev, "CFMWS range %#llx-%#llx not registered\n",
-			cfmws->base_hpa,
-			cfmws->base_hpa + cfmws->window_size - 1);
+	if (rc)
 		return rc;
-	}
 
 	rc = eiw_to_ways(cfmws->interleave_ways, &ways);
 	if (rc)
@@ -352,10 +350,11 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 	if (!res)
 		return -ENOMEM;
 
-	res->name = kasprintf(GFP_KERNEL, "CXL Window %d", ctx->id++);
-	if (!res->name)
-		goto err_name;
+	name = kasprintf(GFP_KERNEL, "CXL Window %d", ctx->id++);
+	if (!name)
+		return -ENOMEM;
 
+	res->name = name;
 	res->start = cfmws->base_hpa;
 	res->end = cfmws->base_hpa + cfmws->window_size - 1;
 	res->flags = IORESOURCE_MEM;
@@ -363,7 +362,9 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 	/* add to the local resource tracking to establish a sort order */
 	rc = insert_resource(cxl_res, res);
 	if (rc)
-		goto err_insert;
+		return rc;
+	name = NULL;
+	res = NULL;
 
 	if (cfmws->interleave_arithmetic == ACPI_CEDT_CFMWS_ARITHMETIC_MODULO)
 		cxl_calc_hb = cxl_hb_modulo;
@@ -375,11 +376,12 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 		return PTR_ERR(cxlrd);
 
 	cxld = &cxlrd->cxlsd.cxld;
+	cxld_dev = &cxld->dev;
 	cxld->flags = cfmws_to_decoder_flags(cfmws->restrictions);
 	cxld->target_type = CXL_DECODER_HOSTONLYMEM;
 	cxld->hpa_range = (struct range) {
-		.start = res->start,
-		.end = res->end,
+		.start = cfmws->base_hpa,
+		.end = cfmws->base_hpa + cfmws->window_size - 1,
 	};
 	cxld->interleave_ways = ways;
 	/*
@@ -399,11 +401,10 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 			rc = acpi_table_parse_cedt(ACPI_CEDT_TYPE_CXIMS,
 						   cxl_parse_cxims, &cxims_ctx);
 			if (rc < 0)
-				goto err_xormap;
+				return rc;
 			if (!cxlrd->platform_data) {
 				dev_err(dev, "No CXIMS for HBIG %u\n", ig);
-				rc = -EINVAL;
-				goto err_xormap;
+				return -EINVAL;
 			}
 		}
 	}
@@ -411,18 +412,10 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 	cxlrd->qos_class = cfmws->qtg_id;
 
 	rc = cxl_decoder_add(cxld, target_map);
-err_xormap:
 	if (rc)
-		put_device(&cxld->dev);
-	else
-		rc = cxl_decoder_autoremove(dev, cxld);
-	return rc;
-
-err_insert:
-	kfree(res->name);
-err_name:
-	kfree(res);
-	return -ENOMEM;
+		return rc;
+	cxld_dev = NULL;
+	return cxl_decoder_autoremove(dev, cxld);
 }
 
 static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
-- 
2.43.0

Re: [PATCH] cxl/acpi: Fix load failures due to single window creation failure

[Jonathan Cameron]

On Wed, 21 Feb 2024 09:31:10 -0800
Dan Williams <dan.j.williams@intel.com> wrote:

> Jonathan Cameron wrote:
> > On Sat, 17 Feb 2024 12:29:32 -0800
> > Dan Williams <dan.j.williams@intel.com> wrote:
> >   
> > > The expectation is that cxl_parse_cfwms() continues in the face the of
> > > failure as evidenced by code like:
> > > 
> > >     cxlrd = cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);
> > >     if (IS_ERR(cxlrd))
> > >     	return 0;
> > > 
> > > There are other error paths in that function which mistakenly follow
> > > idiomatic expectations and return an error when they should not. Most of
> > > those mistakes are innocuous checks that hardly ever fail in practice.
> > > However, a recent change succeed in making the implementation more
> > > fragile by applying an idiomatic, but still wrong "fix" [1]. In this
> > > failure case the kernel reports:
> > > 
> > >     cxl root0: Failed to populate active decoder targets
> > >     cxl_acpi ACPI0017:00: Failed to add decode range: [mem 0x00000000-0x7fffffff flags 0x200]
> > > 
> > > ...which is a real issue with that one window (to be fixed separately),
> > > but ends up failing the entirety of cxl_acpi_probe().
> > > 
> > > Undo that recent breakage while also removing the confusion about
> > > ignoring errors. Update all exits paths to return an error per typical
> > > expectations and let an outer wrapper function handle dropping the
> > > error.
> > > 
> > > Fixes: 91019b5bc7c2 ("cxl/acpi: Return 'rc' instead of '0' in cxl_parse_cfmws()") [1]
> > > Cc: <stable@vger.kernel.org>
> > > Cc: Breno Leitao <leitao@debian.org>
> > > Cc: Alison Schofield <alison.schofield@intel.com>
> > > Cc: Vishal Verma <vishal.l.verma@intel.com>
> > > Signed-off-by: Dan Williams <dan.j.williams@intel.com>  
> > 
> > General idea makes a lot of sense to me.
> > 
> > A few comments on specific implementation inline
> >   
> > > ---
> > >  drivers/cxl/acpi.c |   45 +++++++++++++++++++++++++++------------------
> > >  1 file changed, 27 insertions(+), 18 deletions(-)
> > > 
> > > diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> > > index dcf2b39e1048..53d2dff0c7a3 100644
> > > --- a/drivers/cxl/acpi.c
> > > +++ b/drivers/cxl/acpi.c
> > > @@ -316,31 +316,27 @@ static const struct cxl_root_ops acpi_root_ops = {
> > >  	.qos_class = cxl_acpi_qos_class,
> > >  };
> > >  
> > > -static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> > > -			   const unsigned long end)
> > > +static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
> > > +			     struct cxl_cfmws_context *ctx)
> > >  {
> > >  	int target_map[CXL_DECODER_MAX_INTERLEAVE];
> > > -	struct cxl_cfmws_context *ctx = arg;
> > >  	struct cxl_port *root_port = ctx->root_port;
> > >  	struct resource *cxl_res = ctx->cxl_res;
> > >  	struct cxl_cxims_context cxims_ctx;
> > >  	struct cxl_root_decoder *cxlrd;
> > >  	struct device *dev = ctx->dev;
> > > -	struct acpi_cedt_cfmws *cfmws;
> > >  	cxl_calc_hb_fn cxl_calc_hb;
> > >  	struct cxl_decoder *cxld;
> > >  	unsigned int ways, i, ig;
> > >  	struct resource *res;
> > >  	int rc;
> > >  
> > > -	cfmws = (struct acpi_cedt_cfmws *) header;
> > > -
> > >  	rc = cxl_acpi_cfmws_verify(dev, cfmws);
> > >  	if (rc) {
> > >  		dev_err(dev, "CFMWS range %#llx-%#llx not registered\n",
> > >  			cfmws->base_hpa,
> > >  			cfmws->base_hpa + cfmws->window_size - 1);  
> > 
> > Why keep this error print?  
> 
> True, that can go.
> 
> > > -		return 0;
> > > +		return rc;
> > >  	}
> > >  
> > >  	rc = eiw_to_ways(cfmws->interleave_ways, &ways);
> > > @@ -376,7 +372,7 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> > >  
> > >  	cxlrd = cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);
> > >  	if (IS_ERR(cxlrd))
> > > -		return 0;
> > > +		return PTR_ERR(cxlrd);
> > >  
> > >  	cxld = &cxlrd->cxlsd.cxld;
> > >  	cxld->flags = cfmws_to_decoder_flags(cfmws->restrictions);
> > > @@ -420,16 +416,7 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> > >  		put_device(&cxld->dev);
> > >  	else
> > >  		rc = cxl_decoder_autoremove(dev, cxld);
> > > -	if (rc) {
> > > -		dev_err(dev, "Failed to add decode range: %pr", res);
> > > -		return rc;  
> > 
> > As no longer sharing this message. Might be neater to have this lot as
> > 	rc = cxl_decoder_add(cxld, target_map);
> > err_xormap:
> > 	if (rc) {
> > 		put_device(&cxld->dev);
> > 		return rc;
> > 	}
> > 
> > 	return cxl_decoder_autoremove(dev, cxld);
> > 
> > or a second error exit path.
> > 
> > 	rc = cxl_decoder_add(cxld, target_map);
> > 	if (rc)
> > 		goto err_put_devie;
> > 
> > 	return cxl_decoder_autoremove(dev, cxld;
> > 
> > err_put_device;
> > 	put_device(&cxld->dev);
> > 	return rc;
> > 
> > err_insert:
> > 	kfree(res->name); ...  
> 
> True, there's enough here to do an even deeper cleanup... below.
> 
> > 
> >   
> > > -	}
> > > -	dev_dbg(dev, "add: %s node: %d range [%#llx - %#llx]\n",
> > > -		dev_name(&cxld->dev),
> > > -		phys_to_target_node(cxld->hpa_range.start),
> > > -		cxld->hpa_range.start, cxld->hpa_range.end);
> > > -
> > > -	return 0;
> > > +	return rc;
> > >  
> > >  err_insert:
> > >  	kfree(res->name);
> > > @@ -438,6 +425,28 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> > >  	return -ENOMEM;
> > >  }
> > >  
> > > +static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> > > +			   const unsigned long end)
> > > +{
> > > +	struct acpi_cedt_cfmws *cfmws = (struct acpi_cedt_cfmws *)header;
> > > +	struct cxl_cfmws_context *ctx = arg;
> > > +	struct device *dev = ctx->dev;
> > > +	int rc;
> > > +
> > > +	dev_dbg(dev, "decode range: node: %d range [%#llx - %#llx]\n",
> > > +		phys_to_target_node(cfmws->base_hpa), cfmws->base_hpa,
> > > +		cfmws->base_hpa + cfmws->window_size - 1);  
> > 
> > Could maybe put this in an else below?
> >   
> > > +	rc = __cxl_parse_cfmws(cfmws, ctx);
> > > +	if (rc)
> > > +		dev_err(dev,
> > > +			"Failed to add decode range: [%#llx - %#llx] (%d)\n",
> > > +			cfmws->base_hpa,
> > > +			cfmws->base_hpa + cfmws->window_size - 1, rc);
> > > +  
> > else 
> > 	dev_dbg();
> > 
> > so we only give the dbg version on success?  
> 
> Yeah, I will switch to this since the previous state was also skipping
> the debug messages on success.
> 
> Follow-on cleanup:
> 
> -- 8< --
> From e30c267c0b69d5e4531d8f65ec86e4fa32d72340 Mon Sep 17 00:00:00 2001
> From: Dan Williams <dan.j.williams@intel.com>
> Date: Tue, 20 Feb 2024 22:44:34 -0800
> Subject: [PATCH] cxl/acpi: Cleanup __cxl_parse_cfmws() error exits
> 
> As a follow on to the recent rework of __cxl_parse_cfmws() to always
> return errors, use cleanup.h helpers to remove goto and other cleanups
> now that logging is moved to the cxl_parse_cfmws() wrapper.

This runs into the question of where the declarations should be for
cleanup.h changes.  I can dig out the Linus comment on this but
I'm feeling lazy ;)

In general I like this stuff, but in this case I think it's ended
up harder to read than the original code.

> 
> Reported-by: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
> Closes: http://lore.kernel.org/r/20240219124041.00002bda@Huawei.com
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  drivers/cxl/acpi.c | 45 +++++++++++++++++++--------------------------
>  1 file changed, 19 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> index 1a3e6aafbdcc..b1ea2d152c65 100644
> --- a/drivers/cxl/acpi.c
> +++ b/drivers/cxl/acpi.c
> @@ -319,25 +319,23 @@ static const struct cxl_root_ops acpi_root_ops = {
>  static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
>  			     struct cxl_cfmws_context *ctx)
>  {
> +	struct device *cxld_dev __free(put_device) = NULL;
>  	int target_map[CXL_DECODER_MAX_INTERLEAVE];
>  	struct cxl_port *root_port = ctx->root_port;
> +	struct resource *res __free(kfree) = NULL;
>  	struct resource *cxl_res = ctx->cxl_res;
> +	const char *name __free(kfree) = NULL;

Linus has expressed that he prefers these done inline
so the allocation and clearing are obviously associated - there
is an ordering related factor as well as they will unwind
in the reverse of declaration order, not allocation order.


>  	struct cxl_cxims_context cxims_ctx;
>  	struct cxl_root_decoder *cxlrd;
>  	struct device *dev = ctx->dev;
>  	cxl_calc_hb_fn cxl_calc_hb;
>  	struct cxl_decoder *cxld;
>  	unsigned int ways, i, ig;
> -	struct resource *res;
>  	int rc;
>  
>  	rc = cxl_acpi_cfmws_verify(dev, cfmws);
> -	if (rc) {
> -		dev_err(dev, "CFMWS range %#llx-%#llx not registered\n",
> -			cfmws->base_hpa,
> -			cfmws->base_hpa + cfmws->window_size - 1);
> +	if (rc)
>  		return rc;
> -	}
>  
>  	rc = eiw_to_ways(cfmws->interleave_ways, &ways);
>  	if (rc)
> @@ -352,10 +350,11 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
>  	if (!res)
>  		return -ENOMEM;
>  
> -	res->name = kasprintf(GFP_KERNEL, "CXL Window %d", ctx->id++);
> -	if (!res->name)
> -		goto err_name;

const char *name __free(kfree) = kasprintf(...);

same for the others.
> +	name = kasprintf(GFP_KERNEL, "CXL Window %d", ctx->id++);
> +	if (!name)
> +		return -ENOMEM;
>  
> +	res->name = name;
>  	res->start = cfmws->base_hpa;
>  	res->end = cfmws->base_hpa + cfmws->window_size - 1;
>  	res->flags = IORESOURCE_MEM;
> @@ -363,7 +362,9 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
>  	/* add to the local resource tracking to establish a sort order */
>  	rc = insert_resource(cxl_res, res);
>  	if (rc)
> -		goto err_insert;
> +		return rc;
> +	name = NULL;

I guess we'll get used to this.  Kind of annoying that no_free_ptr() is
defined as __must_check. Otherwise would be good to use that to document
the 'why' of these are being set to NULL.

> +	res = NULL;
>  
>  	if (cfmws->interleave_arithmetic == ACPI_CEDT_CFMWS_ARITHMETIC_MODULO)
>  		cxl_calc_hb = cxl_hb_modulo;
> @@ -375,11 +376,12 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
>  		return PTR_ERR(cxlrd);
>  
>  	cxld = &cxlrd->cxlsd.cxld;
> +	cxld_dev = &cxld->dev;

This I find odd, there is no allocation as such in here so the matching of
the unwind and the allocation isn't clear. 

>  	cxld->flags = cfmws_to_decoder_flags(cfmws->restrictions);
>  	cxld->target_type = CXL_DECODER_HOSTONLYMEM;
>  	cxld->hpa_range = (struct range) {
> -		.start = res->start,
> -		.end = res->end,
> +		.start = cfmws->base_hpa,
> +		.end = cfmws->base_hpa + cfmws->window_size - 1,
>  	};
>  	cxld->interleave_ways = ways;
>  	/*
> @@ -399,11 +401,10 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
>  			rc = acpi_table_parse_cedt(ACPI_CEDT_TYPE_CXIMS,
>  						   cxl_parse_cxims, &cxims_ctx);
>  			if (rc < 0)
> -				goto err_xormap;
> +				return rc;
>  			if (!cxlrd->platform_data) {
>  				dev_err(dev, "No CXIMS for HBIG %u\n", ig);
> -				rc = -EINVAL;
> -				goto err_xormap;
> +				return -EINVAL;
>  			}
>  		}
>  	}
> @@ -411,18 +412,10 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
>  	cxlrd->qos_class = cfmws->qtg_id;
>  
>  	rc = cxl_decoder_add(cxld, target_map);
> -err_xormap:
>  	if (rc)
> -		put_device(&cxld->dev);
> -	else
> -		rc = cxl_decoder_autoremove(dev, cxld);
> -	return rc;
> -
> -err_insert:
> -	kfree(res->name);
> -err_name:
> -	kfree(res);
> -	return -ENOMEM;
> +		return rc;
> +	cxld_dev = NULL;

This is definitely not nice to read.  We are randomly setting an
apparently unrelated pointer to NULL.  At very least the __free
should operating on cxld then we can use

return cxl_decoder_autoremove(dev, no_free_ptr(cxld));

But the get was burred in cxl_root_decoder_alloc() so even that
is non obvious.  You could do the magic to make

struct cxl_root_decoder *cxld __free(cxlroot_put) = 
	cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);

return cxl_decoder_autoremove(dev, &no_free_ptr(cxlrd)->cxlsd.cxld);

Is it worth it? Just about, maybe...


> +	return cxl_decoder_autoremove(dev, cxld);
>  }
>  
>  static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,

Re: [PATCH] cxl/acpi: Fix load failures due to single window creation failure

[Dan Williams]

Jonathan Cameron wrote:
> On Wed, 21 Feb 2024 09:31:10 -0800
> Dan Williams <dan.j.williams@intel.com> wrote:
> 
> > Jonathan Cameron wrote:
> > > On Sat, 17 Feb 2024 12:29:32 -0800
> > > Dan Williams <dan.j.williams@intel.com> wrote:
> > >   
> > > > The expectation is that cxl_parse_cfwms() continues in the face the of
> > > > failure as evidenced by code like:
> > > > 
> > > >     cxlrd = cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);
> > > >     if (IS_ERR(cxlrd))
> > > >     	return 0;
> > > > 
> > > > There are other error paths in that function which mistakenly follow
> > > > idiomatic expectations and return an error when they should not. Most of
> > > > those mistakes are innocuous checks that hardly ever fail in practice.
> > > > However, a recent change succeed in making the implementation more
> > > > fragile by applying an idiomatic, but still wrong "fix" [1]. In this
> > > > failure case the kernel reports:
> > > > 
> > > >     cxl root0: Failed to populate active decoder targets
> > > >     cxl_acpi ACPI0017:00: Failed to add decode range: [mem 0x00000000-0x7fffffff flags 0x200]
> > > > 
> > > > ...which is a real issue with that one window (to be fixed separately),
> > > > but ends up failing the entirety of cxl_acpi_probe().
> > > > 
> > > > Undo that recent breakage while also removing the confusion about
> > > > ignoring errors. Update all exits paths to return an error per typical
> > > > expectations and let an outer wrapper function handle dropping the
> > > > error.
> > > > 
> > > > Fixes: 91019b5bc7c2 ("cxl/acpi: Return 'rc' instead of '0' in cxl_parse_cfmws()") [1]
> > > > Cc: <stable@vger.kernel.org>
> > > > Cc: Breno Leitao <leitao@debian.org>
> > > > Cc: Alison Schofield <alison.schofield@intel.com>
> > > > Cc: Vishal Verma <vishal.l.verma@intel.com>
> > > > Signed-off-by: Dan Williams <dan.j.williams@intel.com>  
> > > 
> > > General idea makes a lot of sense to me.
> > > 
> > > A few comments on specific implementation inline
> > >   
> > > > ---
> > > >  drivers/cxl/acpi.c |   45 +++++++++++++++++++++++++++------------------
> > > >  1 file changed, 27 insertions(+), 18 deletions(-)
> > > > 
> > > > diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> > > > index dcf2b39e1048..53d2dff0c7a3 100644
> > > > --- a/drivers/cxl/acpi.c
> > > > +++ b/drivers/cxl/acpi.c
> > > > @@ -316,31 +316,27 @@ static const struct cxl_root_ops acpi_root_ops = {
> > > >  	.qos_class = cxl_acpi_qos_class,
> > > >  };
> > > >  
> > > > -static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> > > > -			   const unsigned long end)
> > > > +static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
> > > > +			     struct cxl_cfmws_context *ctx)
> > > >  {
> > > >  	int target_map[CXL_DECODER_MAX_INTERLEAVE];
> > > > -	struct cxl_cfmws_context *ctx = arg;
> > > >  	struct cxl_port *root_port = ctx->root_port;
> > > >  	struct resource *cxl_res = ctx->cxl_res;
> > > >  	struct cxl_cxims_context cxims_ctx;
> > > >  	struct cxl_root_decoder *cxlrd;
> > > >  	struct device *dev = ctx->dev;
> > > > -	struct acpi_cedt_cfmws *cfmws;
> > > >  	cxl_calc_hb_fn cxl_calc_hb;
> > > >  	struct cxl_decoder *cxld;
> > > >  	unsigned int ways, i, ig;
> > > >  	struct resource *res;
> > > >  	int rc;
> > > >  
> > > > -	cfmws = (struct acpi_cedt_cfmws *) header;
> > > > -
> > > >  	rc = cxl_acpi_cfmws_verify(dev, cfmws);
> > > >  	if (rc) {
> > > >  		dev_err(dev, "CFMWS range %#llx-%#llx not registered\n",
> > > >  			cfmws->base_hpa,
> > > >  			cfmws->base_hpa + cfmws->window_size - 1);  
> > > 
> > > Why keep this error print?  
> > 
> > True, that can go.
> > 
> > > > -		return 0;
> > > > +		return rc;
> > > >  	}
> > > >  
> > > >  	rc = eiw_to_ways(cfmws->interleave_ways, &ways);
> > > > @@ -376,7 +372,7 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> > > >  
> > > >  	cxlrd = cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);
> > > >  	if (IS_ERR(cxlrd))
> > > > -		return 0;
> > > > +		return PTR_ERR(cxlrd);
> > > >  
> > > >  	cxld = &cxlrd->cxlsd.cxld;
> > > >  	cxld->flags = cfmws_to_decoder_flags(cfmws->restrictions);
> > > > @@ -420,16 +416,7 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> > > >  		put_device(&cxld->dev);
> > > >  	else
> > > >  		rc = cxl_decoder_autoremove(dev, cxld);
> > > > -	if (rc) {
> > > > -		dev_err(dev, "Failed to add decode range: %pr", res);
> > > > -		return rc;  
> > > 
> > > As no longer sharing this message. Might be neater to have this lot as
> > > 	rc = cxl_decoder_add(cxld, target_map);
> > > err_xormap:
> > > 	if (rc) {
> > > 		put_device(&cxld->dev);
> > > 		return rc;
> > > 	}
> > > 
> > > 	return cxl_decoder_autoremove(dev, cxld);
> > > 
> > > or a second error exit path.
> > > 
> > > 	rc = cxl_decoder_add(cxld, target_map);
> > > 	if (rc)
> > > 		goto err_put_devie;
> > > 
> > > 	return cxl_decoder_autoremove(dev, cxld;
> > > 
> > > err_put_device;
> > > 	put_device(&cxld->dev);
> > > 	return rc;
> > > 
> > > err_insert:
> > > 	kfree(res->name); ...  
> > 
> > True, there's enough here to do an even deeper cleanup... below.
> > 
> > > 
> > >   
> > > > -	}
> > > > -	dev_dbg(dev, "add: %s node: %d range [%#llx - %#llx]\n",
> > > > -		dev_name(&cxld->dev),
> > > > -		phys_to_target_node(cxld->hpa_range.start),
> > > > -		cxld->hpa_range.start, cxld->hpa_range.end);
> > > > -
> > > > -	return 0;
> > > > +	return rc;
> > > >  
> > > >  err_insert:
> > > >  	kfree(res->name);
> > > > @@ -438,6 +425,28 @@ static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> > > >  	return -ENOMEM;
> > > >  }
> > > >  
> > > > +static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
> > > > +			   const unsigned long end)
> > > > +{
> > > > +	struct acpi_cedt_cfmws *cfmws = (struct acpi_cedt_cfmws *)header;
> > > > +	struct cxl_cfmws_context *ctx = arg;
> > > > +	struct device *dev = ctx->dev;
> > > > +	int rc;
> > > > +
> > > > +	dev_dbg(dev, "decode range: node: %d range [%#llx - %#llx]\n",
> > > > +		phys_to_target_node(cfmws->base_hpa), cfmws->base_hpa,
> > > > +		cfmws->base_hpa + cfmws->window_size - 1);  
> > > 
> > > Could maybe put this in an else below?
> > >   
> > > > +	rc = __cxl_parse_cfmws(cfmws, ctx);
> > > > +	if (rc)
> > > > +		dev_err(dev,
> > > > +			"Failed to add decode range: [%#llx - %#llx] (%d)\n",
> > > > +			cfmws->base_hpa,
> > > > +			cfmws->base_hpa + cfmws->window_size - 1, rc);
> > > > +  
> > > else 
> > > 	dev_dbg();
> > > 
> > > so we only give the dbg version on success?  
> > 
> > Yeah, I will switch to this since the previous state was also skipping
> > the debug messages on success.
> > 
> > Follow-on cleanup:
> > 
> > -- 8< --
> > From e30c267c0b69d5e4531d8f65ec86e4fa32d72340 Mon Sep 17 00:00:00 2001
> > From: Dan Williams <dan.j.williams@intel.com>
> > Date: Tue, 20 Feb 2024 22:44:34 -0800
> > Subject: [PATCH] cxl/acpi: Cleanup __cxl_parse_cfmws() error exits
> > 
> > As a follow on to the recent rework of __cxl_parse_cfmws() to always
> > return errors, use cleanup.h helpers to remove goto and other cleanups
> > now that logging is moved to the cxl_parse_cfmws() wrapper.
> 
> This runs into the question of where the declarations should be for
> cleanup.h changes.  I can dig out the Linus comment on this but
> I'm feeling lazy ;)
> 
> In general I like this stuff, but in this case I think it's ended
> up harder to read than the original code.
> 
> > 
> > Reported-by: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
> > Closes: http://lore.kernel.org/r/20240219124041.00002bda@Huawei.com
> > Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> > ---
> >  drivers/cxl/acpi.c | 45 +++++++++++++++++++--------------------------
> >  1 file changed, 19 insertions(+), 26 deletions(-)
> > 
> > diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> > index 1a3e6aafbdcc..b1ea2d152c65 100644
> > --- a/drivers/cxl/acpi.c
> > +++ b/drivers/cxl/acpi.c
> > @@ -319,25 +319,23 @@ static const struct cxl_root_ops acpi_root_ops = {
> >  static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
> >  			     struct cxl_cfmws_context *ctx)
> >  {
> > +	struct device *cxld_dev __free(put_device) = NULL;
> >  	int target_map[CXL_DECODER_MAX_INTERLEAVE];
> >  	struct cxl_port *root_port = ctx->root_port;
> > +	struct resource *res __free(kfree) = NULL;
> >  	struct resource *cxl_res = ctx->cxl_res;
> > +	const char *name __free(kfree) = NULL;
> 
> Linus has expressed that he prefers these done inline
> so the allocation and clearing are obviously associated - there
> is an ordering related factor as well as they will unwind
> in the reverse of declaration order, not allocation order.

I considered that, yeah I came to the wrong conclusion, will move the
declarations down.

> 
> 
> >  	struct cxl_cxims_context cxims_ctx;
> >  	struct cxl_root_decoder *cxlrd;
> >  	struct device *dev = ctx->dev;
> >  	cxl_calc_hb_fn cxl_calc_hb;
> >  	struct cxl_decoder *cxld;
> >  	unsigned int ways, i, ig;
> > -	struct resource *res;
> >  	int rc;
> >  
> >  	rc = cxl_acpi_cfmws_verify(dev, cfmws);
> > -	if (rc) {
> > -		dev_err(dev, "CFMWS range %#llx-%#llx not registered\n",
> > -			cfmws->base_hpa,
> > -			cfmws->base_hpa + cfmws->window_size - 1);
> > +	if (rc)
> >  		return rc;
> > -	}
> >  
> >  	rc = eiw_to_ways(cfmws->interleave_ways, &ways);
> >  	if (rc)
> > @@ -352,10 +350,11 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
> >  	if (!res)
> >  		return -ENOMEM;
> >  
> > -	res->name = kasprintf(GFP_KERNEL, "CXL Window %d", ctx->id++);
> > -	if (!res->name)
> > -		goto err_name;
> 
> const char *name __free(kfree) = kasprintf(...);
> 
> same for the others.
> > +	name = kasprintf(GFP_KERNEL, "CXL Window %d", ctx->id++);
> > +	if (!name)
> > +		return -ENOMEM;
> >  
> > +	res->name = name;
> >  	res->start = cfmws->base_hpa;
> >  	res->end = cfmws->base_hpa + cfmws->window_size - 1;
> >  	res->flags = IORESOURCE_MEM;
> > @@ -363,7 +362,9 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
> >  	/* add to the local resource tracking to establish a sort order */
> >  	rc = insert_resource(cxl_res, res);
> >  	if (rc)
> > -		goto err_insert;
> > +		return rc;
> > +	name = NULL;
> 
> I guess we'll get used to this.  Kind of annoying that no_free_ptr() is
> defined as __must_check. Otherwise would be good to use that to document
> the 'why' of these are being set to NULL.

This is the main part I am unhappy about as well.

What I would love is some way to declare that if a given statement is
successfull then "list of variables" cleanup-scope has ended. Something
like:

   cond_no_free_ptr(condition, fail_statement, ...);

...to be able to write:

   cond_no_free_ptr(rc == 0, return rc, name, res);

...where it handles setting all passed VA_ARG pointers to NULL.

> 
> > +	res = NULL;
> >  
> >  	if (cfmws->interleave_arithmetic == ACPI_CEDT_CFMWS_ARITHMETIC_MODULO)
> >  		cxl_calc_hb = cxl_hb_modulo;
> > @@ -375,11 +376,12 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
> >  		return PTR_ERR(cxlrd);
> >  
> >  	cxld = &cxlrd->cxlsd.cxld;
> > +	cxld_dev = &cxld->dev;
> 
> This I find odd, there is no allocation as such in here so the matching of
> the unwind and the allocation isn't clear. 

Yes, another moment of weakness, every time I write this pattern it
really indicates the need for a new DEFINE_FREE(). I will add one for
cxl_root_decoder_alloc().

> >  	cxld->flags = cfmws_to_decoder_flags(cfmws->restrictions);
> >  	cxld->target_type = CXL_DECODER_HOSTONLYMEM;
> >  	cxld->hpa_range = (struct range) {
> > -		.start = res->start,
> > -		.end = res->end,
> > +		.start = cfmws->base_hpa,
> > +		.end = cfmws->base_hpa + cfmws->window_size - 1,
> >  	};
> >  	cxld->interleave_ways = ways;
> >  	/*
> > @@ -399,11 +401,10 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
> >  			rc = acpi_table_parse_cedt(ACPI_CEDT_TYPE_CXIMS,
> >  						   cxl_parse_cxims, &cxims_ctx);
> >  			if (rc < 0)
> > -				goto err_xormap;
> > +				return rc;
> >  			if (!cxlrd->platform_data) {
> >  				dev_err(dev, "No CXIMS for HBIG %u\n", ig);
> > -				rc = -EINVAL;
> > -				goto err_xormap;
> > +				return -EINVAL;
> >  			}
> >  		}
> >  	}
> > @@ -411,18 +412,10 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
> >  	cxlrd->qos_class = cfmws->qtg_id;
> >  
> >  	rc = cxl_decoder_add(cxld, target_map);
> > -err_xormap:
> >  	if (rc)
> > -		put_device(&cxld->dev);
> > -	else
> > -		rc = cxl_decoder_autoremove(dev, cxld);
> > -	return rc;
> > -
> > -err_insert:
> > -	kfree(res->name);
> > -err_name:
> > -	kfree(res);
> > -	return -ENOMEM;
> > +		return rc;
> > +	cxld_dev = NULL;
> 
> This is definitely not nice to read.  We are randomly setting an
> apparently unrelated pointer to NULL.  At very least the __free
> should operating on cxld then we can use
> 
> return cxl_decoder_autoremove(dev, no_free_ptr(cxld));

That looks nice, and would look even nicer as:

   return cxl_root_decoder_autoremove(dev, no_free_ptr(cxlrd));

...i.e. paired with the new DEFINE_FREE() for cxl_root_decoder_alloc().

Re: [PATCH] cxl/acpi: Fix load failures due to single window creation failure

[Dan Williams]

Dan Williams wrote:
[..]
> > This is definitely not nice to read.  We are randomly setting an
> > apparently unrelated pointer to NULL.  At very least the __free
> > should operating on cxld then we can use

So, how about this... I don't hate it:

-- 8< --
diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index 1a3e6aafbdcc..94ff38960f99 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -316,6 +316,8 @@ static const struct cxl_root_ops acpi_root_ops = {
 	.qos_class = cxl_acpi_qos_class,
 };
 
+DEFINE_FREE(put_cxlrd, struct cxl_root_decoder *,
+	    if (!IS_ERR_OR_NULL(_T)) put_device(&_T->cxlsd.cxld.dev))
 static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 			     struct cxl_cfmws_context *ctx)
 {
@@ -328,16 +330,11 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 	cxl_calc_hb_fn cxl_calc_hb;
 	struct cxl_decoder *cxld;
 	unsigned int ways, i, ig;
-	struct resource *res;
 	int rc;
 
 	rc = cxl_acpi_cfmws_verify(dev, cfmws);
-	if (rc) {
-		dev_err(dev, "CFMWS range %#llx-%#llx not registered\n",
-			cfmws->base_hpa,
-			cfmws->base_hpa + cfmws->window_size - 1);
+	if (rc)
 		return rc;
-	}
 
 	rc = eiw_to_ways(cfmws->interleave_ways, &ways);
 	if (rc)
@@ -348,29 +345,31 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 	for (i = 0; i < ways; i++)
 		target_map[i] = cfmws->interleave_targets[i];
 
-	res = kzalloc(sizeof(*res), GFP_KERNEL);
+	struct resource *res __free(kfree) = kzalloc(sizeof(*res), GFP_KERNEL);
 	if (!res)
 		return -ENOMEM;
 
-	res->name = kasprintf(GFP_KERNEL, "CXL Window %d", ctx->id++);
-	if (!res->name)
-		goto err_name;
+	const char *name __free(kfree) =
+		kasprintf(GFP_KERNEL, "CXL Window %d", ctx->id++);
+	if (!name)
+		return -ENOMEM;
 
+	res->name = name;
 	res->start = cfmws->base_hpa;
 	res->end = cfmws->base_hpa + cfmws->window_size - 1;
 	res->flags = IORESOURCE_MEM;
 
 	/* add to the local resource tracking to establish a sort order */
 	rc = insert_resource(cxl_res, res);
-	if (rc)
-		goto err_insert;
+	cond_no_free_ptr(rc == 0, return rc, res, name);
 
 	if (cfmws->interleave_arithmetic == ACPI_CEDT_CFMWS_ARITHMETIC_MODULO)
 		cxl_calc_hb = cxl_hb_modulo;
 	else
 		cxl_calc_hb = cxl_hb_xor;
 
-	cxlrd = cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);
+	struct cxl_root_decocder *cxlrd __free(put_cxlrd) =
+		cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);
 	if (IS_ERR(cxlrd))
 		return PTR_ERR(cxlrd);
 
@@ -378,8 +377,8 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 	cxld->flags = cfmws_to_decoder_flags(cfmws->restrictions);
 	cxld->target_type = CXL_DECODER_HOSTONLYMEM;
 	cxld->hpa_range = (struct range) {
-		.start = res->start,
-		.end = res->end,
+		.start = cfmws->base_hpa,
+		.end = cfmws->base_hpa + cfmws->window_size - 1,
 	};
 	cxld->interleave_ways = ways;
 	/*
@@ -399,11 +398,10 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 			rc = acpi_table_parse_cedt(ACPI_CEDT_TYPE_CXIMS,
 						   cxl_parse_cxims, &cxims_ctx);
 			if (rc < 0)
-				goto err_xormap;
+				return rc;
 			if (!cxlrd->platform_data) {
 				dev_err(dev, "No CXIMS for HBIG %u\n", ig);
-				rc = -EINVAL;
-				goto err_xormap;
+				return -EINVAL;
 			}
 		}
 	}
@@ -411,18 +409,9 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 	cxlrd->qos_class = cfmws->qtg_id;
 
 	rc = cxl_decoder_add(cxld, target_map);
-err_xormap:
 	if (rc)
-		put_device(&cxld->dev);
-	else
-		rc = cxl_decoder_autoremove(dev, cxld);
-	return rc;
-
-err_insert:
-	kfree(res->name);
-err_name:
-	kfree(res);
-	return -ENOMEM;
+		return rc;
+	return cxl_root_decoder_autoremove(dev, no_free_ptr(cxlrd));
 }
 
 static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 003feebab79b..8bc044a4a965 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -776,6 +776,11 @@ int cxl_decoder_add(struct cxl_decoder *cxld, int *target_map);
 struct cxl_endpoint_decoder *cxl_endpoint_decoder_alloc(struct cxl_port *port);
 int cxl_decoder_add_locked(struct cxl_decoder *cxld, int *target_map);
 int cxl_decoder_autoremove(struct device *host, struct cxl_decoder *cxld);
+static inline int cxl_root_decoder_autoremove(struct device *host,
+					      struct cxl_root_decoder *cxlrd)
+{
+	return cxl_decoder_autoremove(host, &cxlrd->cxlsd.cxld);
+}
 int cxl_endpoint_autoremove(struct cxl_memdev *cxlmd, struct cxl_port *endpoint);
 
 /**
diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
index c2d09bc4f976..9bf242e22191 100644
--- a/include/linux/cleanup.h
+++ b/include/linux/cleanup.h
@@ -77,6 +77,29 @@ const volatile void * __must_check_fn(const volatile void *val)
 
 #define return_ptr(p)	return no_free_ptr(p)
 
+#define __cond_no_free_ptrs(p) ({__auto_type __always_unused __ptr = no_free_ptr(p);})
+#define __cond_no_free_ptrs1(p, ...) __cond_no_free_ptrs(p)
+#define __cond_no_free_ptrs2(p, ...) \
+	__cond_no_free_ptrs(p), __cond_no_free_ptrs1(__VA_ARGS__)
+#define __cond_no_free_ptrs3(p, ...) \
+	__cond_no_free_ptrs(p), __cond_no_free_ptrs2(__VA_ARGS__)
+
+/* 
+ * When an object is built up by an amalgamation of multiple
+ * allocations each of those need to be cleaned up on error, but once
+ * the object is registered all of those cleanups can be cancelled.
+ * cond_no_free_ptr() arranges to call no_free_ptr() on all its
+ * arguments (up to 3) if @condition is true and runs @_fail otherwise
+ * (typically to return and trigger auto-cleanup).
+ */
+#define cond_no_free_ptr(condition, _fail, ...)                           \
+	if (condition) {                                                  \
+		CONCATENATE(__cond_no_free_ptrs, COUNT_ARGS(__VA_ARGS__)) \
+		(__VA_ARGS__);                                            \
+		BUILD_BUG_ON(COUNT_ARGS(__VA_ARGS__) > 3);                \
+	} else {                                                          \
+		_fail;                                                    \
+	}
 
 /*
  * DEFINE_CLASS(name, type, exit, init, init_args...):

Re: [PATCH] cxl/acpi: Fix load failures due to single window creation failure

[Dan Williams]

Dan Williams wrote:
> Dan Williams wrote:
> [..]
> > > This is definitely not nice to read.  We are randomly setting an
> > > apparently unrelated pointer to NULL.  At very least the __free
> > > should operating on cxld then we can use
> 
> So, how about this... I don't hate it:

...and the version that actually compiles, fixed up cxl_root_decoder
declaration and dropped the BUILD_BUG_ON() since it will naturally fail
to compile if more than the supported number of variables is passed to
cond_no_free_ptr():

-- 8< --
diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index 1a3e6aafbdcc..5c1dc4adf80d 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -316,6 +316,8 @@ static const struct cxl_root_ops acpi_root_ops = {
 	.qos_class = cxl_acpi_qos_class,
 };
 
+DEFINE_FREE(put_cxlrd, struct cxl_root_decoder *,
+	    if (!IS_ERR_OR_NULL(_T)) put_device(&_T->cxlsd.cxld.dev))
 static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 			     struct cxl_cfmws_context *ctx)
 {
@@ -323,21 +325,15 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 	struct cxl_port *root_port = ctx->root_port;
 	struct resource *cxl_res = ctx->cxl_res;
 	struct cxl_cxims_context cxims_ctx;
-	struct cxl_root_decoder *cxlrd;
 	struct device *dev = ctx->dev;
 	cxl_calc_hb_fn cxl_calc_hb;
 	struct cxl_decoder *cxld;
 	unsigned int ways, i, ig;
-	struct resource *res;
 	int rc;
 
 	rc = cxl_acpi_cfmws_verify(dev, cfmws);
-	if (rc) {
-		dev_err(dev, "CFMWS range %#llx-%#llx not registered\n",
-			cfmws->base_hpa,
-			cfmws->base_hpa + cfmws->window_size - 1);
+	if (rc)
 		return rc;
-	}
 
 	rc = eiw_to_ways(cfmws->interleave_ways, &ways);
 	if (rc)
@@ -348,29 +344,31 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 	for (i = 0; i < ways; i++)
 		target_map[i] = cfmws->interleave_targets[i];
 
-	res = kzalloc(sizeof(*res), GFP_KERNEL);
+	struct resource *res __free(kfree) = kzalloc(sizeof(*res), GFP_KERNEL);
 	if (!res)
 		return -ENOMEM;
 
-	res->name = kasprintf(GFP_KERNEL, "CXL Window %d", ctx->id++);
-	if (!res->name)
-		goto err_name;
+	const char *name __free(kfree) =
+		kasprintf(GFP_KERNEL, "CXL Window %d", ctx->id++);
+	if (!name)
+		return -ENOMEM;
 
+	res->name = name;
 	res->start = cfmws->base_hpa;
 	res->end = cfmws->base_hpa + cfmws->window_size - 1;
 	res->flags = IORESOURCE_MEM;
 
 	/* add to the local resource tracking to establish a sort order */
 	rc = insert_resource(cxl_res, res);
-	if (rc)
-		goto err_insert;
+	cond_no_free_ptr(rc == 0, return rc, res, name);
 
 	if (cfmws->interleave_arithmetic == ACPI_CEDT_CFMWS_ARITHMETIC_MODULO)
 		cxl_calc_hb = cxl_hb_modulo;
 	else
 		cxl_calc_hb = cxl_hb_xor;
 
-	cxlrd = cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);
+	struct cxl_root_decoder *cxlrd __free(put_cxlrd) =
+		cxl_root_decoder_alloc(root_port, ways, cxl_calc_hb);
 	if (IS_ERR(cxlrd))
 		return PTR_ERR(cxlrd);
 
@@ -378,8 +376,8 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 	cxld->flags = cfmws_to_decoder_flags(cfmws->restrictions);
 	cxld->target_type = CXL_DECODER_HOSTONLYMEM;
 	cxld->hpa_range = (struct range) {
-		.start = res->start,
-		.end = res->end,
+		.start = cfmws->base_hpa,
+		.end = cfmws->base_hpa + cfmws->window_size - 1,
 	};
 	cxld->interleave_ways = ways;
 	/*
@@ -399,11 +397,10 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 			rc = acpi_table_parse_cedt(ACPI_CEDT_TYPE_CXIMS,
 						   cxl_parse_cxims, &cxims_ctx);
 			if (rc < 0)
-				goto err_xormap;
+				return rc;
 			if (!cxlrd->platform_data) {
 				dev_err(dev, "No CXIMS for HBIG %u\n", ig);
-				rc = -EINVAL;
-				goto err_xormap;
+				return -EINVAL;
 			}
 		}
 	}
@@ -411,18 +408,9 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 	cxlrd->qos_class = cfmws->qtg_id;
 
 	rc = cxl_decoder_add(cxld, target_map);
-err_xormap:
 	if (rc)
-		put_device(&cxld->dev);
-	else
-		rc = cxl_decoder_autoremove(dev, cxld);
-	return rc;
-
-err_insert:
-	kfree(res->name);
-err_name:
-	kfree(res);
-	return -ENOMEM;
+		return rc;
+	return cxl_root_decoder_autoremove(dev, no_free_ptr(cxlrd));
 }
 
 static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 003feebab79b..8bc044a4a965 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -776,6 +776,11 @@ int cxl_decoder_add(struct cxl_decoder *cxld, int *target_map);
 struct cxl_endpoint_decoder *cxl_endpoint_decoder_alloc(struct cxl_port *port);
 int cxl_decoder_add_locked(struct cxl_decoder *cxld, int *target_map);
 int cxl_decoder_autoremove(struct device *host, struct cxl_decoder *cxld);
+static inline int cxl_root_decoder_autoremove(struct device *host,
+					      struct cxl_root_decoder *cxlrd)
+{
+	return cxl_decoder_autoremove(host, &cxlrd->cxlsd.cxld);
+}
 int cxl_endpoint_autoremove(struct cxl_memdev *cxlmd, struct cxl_port *endpoint);
 
 /**
diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
index c2d09bc4f976..e156fed88f51 100644
--- a/include/linux/cleanup.h
+++ b/include/linux/cleanup.h
@@ -77,6 +77,28 @@ const volatile void * __must_check_fn(const volatile void *val)
 
 #define return_ptr(p)	return no_free_ptr(p)
 
+#define __cond_no_free_ptrs(p) ({__auto_type __always_unused __ptr = no_free_ptr(p);})
+#define __cond_no_free_ptrs1(p, ...) __cond_no_free_ptrs(p)
+#define __cond_no_free_ptrs2(p, ...) \
+	__cond_no_free_ptrs(p), __cond_no_free_ptrs1(__VA_ARGS__)
+#define __cond_no_free_ptrs3(p, ...) \
+	__cond_no_free_ptrs(p), __cond_no_free_ptrs2(__VA_ARGS__)
+
+/*
+ * When an object is built up by an amalgamation of multiple allocations
+ * each of those need to be cleaned up on error, but there are occasions
+ * where once the object is registered all of those cleanups can be
+ * cancelled.  cond_no_free_ptr() arranges to call no_free_ptr() on all
+ * its arguments (up to 3) if @condition is true and runs @_fail
+ * otherwise (typically to return and trigger auto-cleanup).
+ */
+#define cond_no_free_ptr(condition, _fail, ...)                           \
+	if (condition) {                                                  \
+		CONCATENATE(__cond_no_free_ptrs, COUNT_ARGS(__VA_ARGS__)) \
+		(__VA_ARGS__);                                            \
+	} else {                                                          \
+		_fail;                                                    \
+	}
 
 /*
  * DEFINE_CLASS(name, type, exit, init, init_args...):

Re: [PATCH] cxl/acpi: Fix load failures due to single window creation failure

[Jonathan Cameron]

On Sat, 24 Feb 2024 11:30:27 -0800
Dan Williams <dan.j.williams@intel.com> wrote:

> Dan Williams wrote:
> > Dan Williams wrote:
> > [..]  
> > > > This is definitely not nice to read.  We are randomly setting an
> > > > apparently unrelated pointer to NULL.  At very least the __free
> > > > should operating on cxld then we can use  
> > 
> > So, how about this... I don't hate it:  
> 
> ...and the version that actually compiles, fixed up cxl_root_decoder
> declaration and dropped the BUILD_BUG_ON() since it will naturally fail
> to compile if more than the supported number of variables is passed to
> cond_no_free_ptr():
> 
> -- 8< --
> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> index 1a3e6aafbdcc..5c1dc4adf80d 100644
> --- a/drivers/cxl/acpi.c
> +++ b/drivers/cxl/acpi.c
> @@ -316,6 +316,8 @@ static const struct cxl_root_ops acpi_root_ops = {
>  	.qos_class = cxl_acpi_qos_class,
>  };
>  
> +DEFINE_FREE(put_cxlrd, struct cxl_root_decoder *,
> +	    if (!IS_ERR_OR_NULL(_T)) put_device(&_T->cxlsd.cxld.dev))
>  static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
>  			     struct cxl_cfmws_context *ctx)
>  {
> @@ -323,21 +325,15 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,


>  	/* add to the local resource tracking to establish a sort order */
>  	rc = insert_resource(cxl_res, res);
> -	if (rc)
> -		goto err_insert;
> +	cond_no_free_ptr(rc == 0, return rc, res, name);

I'm not convinced this is that much clearer than
	rc = insert_resource(cxl_res, res);
	if (rc)
		return rc;
	no_check_no_free_ptrs(res);
	no_check_no_free_ptrs(name);

with better naming and with that being defined in similar way to your
__cond_no_free_ptrs()

Just keeping them in the same code block is probably enough to indicate
that these are there because of success of insert_resource()
+ no need to handle bigger and bigger sets of params in the future.


Rest looks good to me

Jonathan

 
	

...

> diff --git a/include/linux/cleanup.h b/include/linux/cleanup.h
> index c2d09bc4f976..e156fed88f51 100644
> --- a/include/linux/cleanup.h
> +++ b/include/linux/cleanup.h
> @@ -77,6 +77,28 @@ const volatile void * __must_check_fn(const volatile void *val)
>  
>  #define return_ptr(p)	return no_free_ptr(p)
>  
> +#define __cond_no_free_ptrs(p) ({__auto_type __always_unused __ptr = no_free_ptr(p);})

Nasty ;)

> +#define __cond_no_free_ptrs1(p, ...) __cond_no_free_ptrs(p)
> +#define __cond_no_free_ptrs2(p, ...) \
> +	__cond_no_free_ptrs(p), __cond_no_free_ptrs1(__VA_ARGS__)
> +#define __cond_no_free_ptrs3(p, ...) \
> +	__cond_no_free_ptrs(p), __cond_no_free_ptrs2(__VA_ARGS__)
> +
> +/*
> + * When an object is built up by an amalgamation of multiple allocations
> + * each of those need to be cleaned up on error, but there are occasions
> + * where once the object is registered all of those cleanups can be
> + * cancelled.  cond_no_free_ptr() arranges to call no_free_ptr() on all
> + * its arguments (up to 3) if @condition is true and runs @_fail
> + * otherwise (typically to return and trigger auto-cleanup).
> + */
> +#define cond_no_free_ptr(condition, _fail, ...)                           \
> +	if (condition) {                                                  \
> +		CONCATENATE(__cond_no_free_ptrs, COUNT_ARGS(__VA_ARGS__)) \
> +		(__VA_ARGS__);                                            \
> +	} else {                                                          \
> +		_fail;                                                    \
> +	}
>  
>  /*
>   * DEFINE_CLASS(name, type, exit, init, init_args...):

Re: [PATCH] cxl/acpi: Fix load failures due to single window creation failure

[Dan Williams]

Jonathan Cameron wrote:
> On Sat, 24 Feb 2024 11:30:27 -0800
> Dan Williams <dan.j.williams@intel.com> wrote:
> 
> > Dan Williams wrote:
> > > Dan Williams wrote:
> > > [..]  
> > > > > This is definitely not nice to read.  We are randomly setting an
> > > > > apparently unrelated pointer to NULL.  At very least the __free
> > > > > should operating on cxld then we can use  
> > > 
> > > So, how about this... I don't hate it:  
> > 
> > ...and the version that actually compiles, fixed up cxl_root_decoder
> > declaration and dropped the BUILD_BUG_ON() since it will naturally fail
> > to compile if more than the supported number of variables is passed to
> > cond_no_free_ptr():
> > 
> > -- 8< --
> > diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> > index 1a3e6aafbdcc..5c1dc4adf80d 100644
> > --- a/drivers/cxl/acpi.c
> > +++ b/drivers/cxl/acpi.c
> > @@ -316,6 +316,8 @@ static const struct cxl_root_ops acpi_root_ops = {
> >  	.qos_class = cxl_acpi_qos_class,
> >  };
> >  
> > +DEFINE_FREE(put_cxlrd, struct cxl_root_decoder *,
> > +	    if (!IS_ERR_OR_NULL(_T)) put_device(&_T->cxlsd.cxld.dev))
> >  static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
> >  			     struct cxl_cfmws_context *ctx)
> >  {
> > @@ -323,21 +325,15 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
> 
> 
> >  	/* add to the local resource tracking to establish a sort order */
> >  	rc = insert_resource(cxl_res, res);
> > -	if (rc)
> > -		goto err_insert;
> > +	cond_no_free_ptr(rc == 0, return rc, res, name);
> 
> I'm not convinced this is that much clearer than
> 	rc = insert_resource(cxl_res, res);
> 	if (rc)
> 		return rc;
> 	no_check_no_free_ptrs(res);
> 	no_check_no_free_ptrs(name);
> 
> with better naming and with that being defined in similar way to your
> __cond_no_free_ptrs()

Can keep that as a fallback, but if Peter / Linus agree to the syntax of
cond_guard(), which follows from scoped_cond_guard(), I would ask that
they consider cond_no_free_ptr() as well. Single statement termination
of variables paired with the single statement that took on ownership has
an appealing symmetry to me.

> Just keeping them in the same code block is probably enough to indicate
> that these are there because of success of insert_resource()
> + no need to handle bigger and bigger sets of params in the future.
> 
> 
> Rest looks good to me

Thanks for taking a look. I'll run cond_no_free_ptr() by more folks and
if it continues to get a cold reception I'll drop it, or maybe a third
way develops...