cxl/core: Split decoder setup into alloc + add

The kbuild robot reports:

    drivers/cxl/core/bus.c:516:1: warning: stack frame size (1032) exceeds
    limit (1024) in function 'devm_cxl_add_decoder'

It is also the case the devm_cxl_add_decoder() is unwieldy to use for
all the different decoder types. Fix the stack usage by splitting the
creation into alloc and add steps. This also allows for context
specific construction before adding.

With the split the caller is responsible for registering a devm callback
to trigger device_unregister() for the decoder rather than it being
implicit in the decoder registration. I.e. the routine that calls alloc
is responsible for calling put_device() if the "add" operation fails.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Nathan Chancellor <nathan@kernel.org>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/163225205828.3038145.6831131648369404859.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 42 insertions, 87 deletions

diff --git a/drivers/cxl/core/bus.c b/drivers/cxl/core/bus.c
index 6dfdeaf999f0..ebd061d03950 100644
--- a/drivers/cxl/core/bus.c
+++ b/drivers/cxl/core/bus.c
@@ -453,10 +453,8 @@ err:
 }
 EXPORT_SYMBOL_GPL(cxl_add_dport);
 
-static int decoder_populate_targets(struct device *host,
-				    struct cxl_decoder *cxld,
-				    struct cxl_port *port, int *target_map,
-				    int nr_targets)
+static int decoder_populate_targets(struct cxl_decoder *cxld,
+				    struct cxl_port *port, int *target_map)
 {
 	int rc = 0, i;
 
@@ -464,66 +462,48 @@ static int decoder_populate_targets(struct device *host,
 		return 0;
 
 	device_lock(&port->dev);
-	for (i = 0; i < nr_targets; i++) {
+	if (list_empty(&port->dports)) {
+		rc = -EINVAL;
+		goto out_unlock;
+	}
+
+	for (i = 0; i < cxld->nr_targets; i++) {
 		struct cxl_dport *dport = find_dport(port, target_map[i]);
 
 		if (!dport) {
 			rc = -ENXIO;
-			break;
+			goto out_unlock;
 		}
-		dev_dbg(host, "%s: target: %d\n", dev_name(dport->dport), i);
 		cxld->target[i] = dport;
 	}
+
+out_unlock:
 	device_unlock(&port->dev);
 
 	return rc;
 }
 
-static struct cxl_decoder *
-cxl_decoder_alloc(struct device *host, struct cxl_port *port, int nr_targets,
-		  resource_size_t base, resource_size_t len,
-		  int interleave_ways, int interleave_granularity,
-		  enum cxl_decoder_type type, unsigned long flags,
-		  int *target_map)
+struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port, int nr_targets)
 {
-	struct cxl_decoder *cxld;
+	struct cxl_decoder *cxld, cxld_const_init = {
+		.nr_targets = nr_targets,
+	};
 	struct device *dev;
 	int rc = 0;
 
-	if (interleave_ways < 1)
+	if (nr_targets > CXL_DECODER_MAX_INTERLEAVE || nr_targets < 1)
 		return ERR_PTR(-EINVAL);
 
-	device_lock(&port->dev);
-	if (list_empty(&port->dports))
-		rc = -EINVAL;
-	device_unlock(&port->dev);
-	if (rc)
-		return ERR_PTR(rc);
-
 	cxld = kzalloc(struct_size(cxld, target, nr_targets), GFP_KERNEL);
 	if (!cxld)
 		return ERR_PTR(-ENOMEM);
+	memcpy(cxld, &cxld_const_init, sizeof(cxld_const_init));
 
 	rc = ida_alloc(&port->decoder_ida, GFP_KERNEL);
 	if (rc < 0)
 		goto err;
 
-	*cxld = (struct cxl_decoder) {
-		.id = rc,
-		.range = {
-			.start = base,
-			.end = base + len - 1,
-		},
-		.flags = flags,
-		.interleave_ways = interleave_ways,
-		.interleave_granularity = interleave_granularity,
-		.target_type = type,
-	};
-
-	rc = decoder_populate_targets(host, cxld, port, target_map, nr_targets);
-	if (rc)
-		goto err;
-
+	cxld->id = rc;
 	dev = &cxld->dev;
 	device_initialize(dev);
 	device_set_pm_not_required(dev);
@@ -541,72 +521,47 @@ err:
 	kfree(cxld);
 	return ERR_PTR(rc);
 }
+EXPORT_SYMBOL_GPL(cxl_decoder_alloc);
 
-struct cxl_decoder *
-devm_cxl_add_decoder(struct device *host, struct cxl_port *port, int nr_targets,
-		     resource_size_t base, resource_size_t len,
-		     int interleave_ways, int interleave_granularity,
-		     enum cxl_decoder_type type, unsigned long flags,
-		     int *target_map)
+int cxl_decoder_add(struct cxl_decoder *cxld, int *target_map)
 {
-	struct cxl_decoder *cxld;
+	struct cxl_port *port;
 	struct device *dev;
 	int rc;
 
-	if (nr_targets > CXL_DECODER_MAX_INTERLEAVE)
-		return ERR_PTR(-EINVAL);
+	if (WARN_ON_ONCE(!cxld))
+		return -EINVAL;
 
-	cxld = cxl_decoder_alloc(host, port, nr_targets, base, len,
-				 interleave_ways, interleave_granularity, type,
-				 flags, target_map);
-	if (IS_ERR(cxld))
-		return cxld;
+	if (WARN_ON_ONCE(IS_ERR(cxld)))
+		return PTR_ERR(cxld);
 
-	dev = &cxld->dev;
-	rc = dev_set_name(dev, "decoder%d.%d", port->id, cxld->id);
-	if (rc)
-		goto err;
+	if (cxld->interleave_ways < 1)
+		return -EINVAL;
 
-	rc = device_add(dev);
+	port = to_cxl_port(cxld->dev.parent);
+	rc = decoder_populate_targets(cxld, port, target_map);
 	if (rc)
-		goto err;
+		return rc;
 
-	rc = devm_add_action_or_reset(host, unregister_cxl_dev, dev);
+	dev = &cxld->dev;
+	rc = dev_set_name(dev, "decoder%d.%d", port->id, cxld->id);
 	if (rc)
-		return ERR_PTR(rc);
-	return cxld;
+		return rc;
 
-err:
-	put_device(dev);
-	return ERR_PTR(rc);
+	return device_add(dev);
 }
-EXPORT_SYMBOL_GPL(devm_cxl_add_decoder);
+EXPORT_SYMBOL_GPL(cxl_decoder_add);
 
-/*
- * Per the CXL specification (8.2.5.12 CXL HDM Decoder Capability Structure)
- * single ported host-bridges need not publish a decoder capability when a
- * passthrough decode can be assumed, i.e. all transactions that the uport sees
- * are claimed and passed to the single dport. Default the range a 0-base
- * 0-length until the first CXL region is activated.
- */
-struct cxl_decoder *devm_cxl_add_passthrough_decoder(struct device *host,
-						     struct cxl_port *port)
+static void cxld_unregister(void *dev)
 {
-	struct cxl_dport *dport;
-	int target_map[1];
-
-	device_lock(&port->dev);
-	dport = list_first_entry_or_null(&port->dports, typeof(*dport), list);
-	device_unlock(&port->dev);
-
-	if (!dport)
-		return ERR_PTR(-ENXIO);
+	device_unregister(dev);
+}
 
-	target_map[0] = dport->port_id;
-	return devm_cxl_add_decoder(host, port, 1, 0, 0, 1, PAGE_SIZE,
-				    CXL_DECODER_EXPANDER, 0, target_map);
+int cxl_decoder_autoremove(struct device *host, struct cxl_decoder *cxld)
+{
+	return devm_add_action_or_reset(host, cxld_unregister, &cxld->dev);
 }
-EXPORT_SYMBOL_GPL(devm_cxl_add_passthrough_decoder);
+EXPORT_SYMBOL_GPL(cxl_decoder_autoremove);
 
 /**
  * __cxl_driver_register - register a driver for the cxl bus