From d35b495ddf92c964eedf2ac86fdbf88dc3e5cbc9 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Mon, 3 Apr 2023 14:39:16 -0700 Subject: cxl/port: Fix find_cxl_root() for RCDs and simplify it The find_cxl_root() helper is used to lookup root decoders and other CXL platform topology information for a given endpoint. It turns out that for RCDs it has never worked. The result of find_cxl_root(&cxlmd->dev) is always NULL for the RCH topology case because it expects to find a cxl_port at the host-bridge. RCH topologies only have the root cxl_port object with the host-bridge as a dport. While there are no reports of this being a problem to date, by inspection region enumeration should crash as a result of this problem, and it does in a local unit test for this scenario. However, an observation that ever since: commit f17b558d6663 ("cxl/pmem: Refactor nvdimm device registration, delete the workqueue") ...all callers of find_cxl_root() occur after the memdev connection to the port topology has been established. That means that find_cxl_root() can be simplified to a walk of the endpoint port topology to the root. Switch to that arrangement which also fixes the RCD bug. Fixes: a32320b71f08 ("cxl/region: Add region autodiscovery") Reviewed-by: Jonathan Cameron Reviewed-by: Dave Jiang Link: https://lore.kernel.org/r/168002857715.50647.344876437247313909.stgit@dwillia2-xfh.jf.intel.com Signed-off-by: Dan Williams --- drivers/cxl/core/pmem.c | 6 +++--- drivers/cxl/core/port.c | 38 +++++++------------------------------- drivers/cxl/core/region.c | 2 +- drivers/cxl/cxl.h | 4 ++-- drivers/cxl/port.c | 2 +- 5 files changed, 14 insertions(+), 38 deletions(-) (limited to 'drivers') diff --git a/drivers/cxl/core/pmem.c b/drivers/cxl/core/pmem.c index c2e4b1093788..f8c38d997252 100644 --- a/drivers/cxl/core/pmem.c +++ b/drivers/cxl/core/pmem.c @@ -62,9 +62,9 @@ static int match_nvdimm_bridge(struct device *dev, void *data) return is_cxl_nvdimm_bridge(dev); } -struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct device *start) +struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_memdev *cxlmd) { - struct cxl_port *port = find_cxl_root(start); + struct cxl_port *port = find_cxl_root(dev_get_drvdata(&cxlmd->dev)); struct device *dev; if (!port) @@ -253,7 +253,7 @@ int devm_cxl_add_nvdimm(struct cxl_memdev *cxlmd) struct device *dev; int rc; - cxl_nvb = cxl_find_nvdimm_bridge(&cxlmd->dev); + cxl_nvb = cxl_find_nvdimm_bridge(cxlmd); if (!cxl_nvb) return -ENODEV; diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c index 8ee6b6e2e2a4..4d1f9c5b5029 100644 --- a/drivers/cxl/core/port.c +++ b/drivers/cxl/core/port.c @@ -823,41 +823,17 @@ static bool dev_is_cxl_root_child(struct device *dev) return false; } -/* Find a 2nd level CXL port that has a dport that is an ancestor of @match */ -static int match_root_child(struct device *dev, const void *match) +struct cxl_port *find_cxl_root(struct cxl_port *port) { - const struct device *iter = NULL; - struct cxl_dport *dport; - struct cxl_port *port; - - if (!dev_is_cxl_root_child(dev)) - return 0; - - port = to_cxl_port(dev); - iter = match; - while (iter) { - dport = cxl_find_dport_by_dev(port, iter); - if (dport) - break; - iter = iter->parent; - } - - return !!iter; -} + struct cxl_port *iter = port; -struct cxl_port *find_cxl_root(struct device *dev) -{ - struct device *port_dev; - struct cxl_port *root; + while (iter && !is_cxl_root(iter)) + iter = to_cxl_port(iter->dev.parent); - port_dev = bus_find_device(&cxl_bus_type, NULL, dev, match_root_child); - if (!port_dev) + if (!iter) return NULL; - - root = to_cxl_port(port_dev->parent); - get_device(&root->dev); - put_device(port_dev); - return root; + get_device(&iter->dev); + return iter; } EXPORT_SYMBOL_NS_GPL(find_cxl_root, CXL); diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c index f29028148806..808f23ec4e2b 100644 --- a/drivers/cxl/core/region.c +++ b/drivers/cxl/core/region.c @@ -2251,7 +2251,7 @@ static struct cxl_pmem_region *cxl_pmem_region_alloc(struct cxl_region *cxlr) * bridge for one device is the same for all. */ if (i == 0) { - cxl_nvb = cxl_find_nvdimm_bridge(&cxlmd->dev); + cxl_nvb = cxl_find_nvdimm_bridge(cxlmd); if (!cxl_nvb) { cxlr_pmem = ERR_PTR(-ENODEV); goto out; diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h index aab87d74474d..044a92d9813e 100644 --- a/drivers/cxl/cxl.h +++ b/drivers/cxl/cxl.h @@ -658,7 +658,7 @@ struct pci_bus *cxl_port_to_pci_bus(struct cxl_port *port); struct cxl_port *devm_cxl_add_port(struct device *host, struct device *uport, resource_size_t component_reg_phys, struct cxl_dport *parent_dport); -struct cxl_port *find_cxl_root(struct device *dev); +struct cxl_port *find_cxl_root(struct cxl_port *port); int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd); void cxl_bus_rescan(void); void cxl_bus_drain(void); @@ -760,7 +760,7 @@ struct cxl_nvdimm *to_cxl_nvdimm(struct device *dev); bool is_cxl_nvdimm(struct device *dev); bool is_cxl_nvdimm_bridge(struct device *dev); int devm_cxl_add_nvdimm(struct cxl_memdev *cxlmd); -struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct device *dev); +struct cxl_nvdimm_bridge *cxl_find_nvdimm_bridge(struct cxl_memdev *cxlmd); #ifdef CONFIG_CXL_REGION bool is_cxl_pmem_region(struct device *dev); diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c index 9c8f46ed336b..22a7ab2bae7c 100644 --- a/drivers/cxl/port.c +++ b/drivers/cxl/port.c @@ -119,7 +119,7 @@ static int cxl_endpoint_port_probe(struct cxl_port *port) * This can't fail in practice as CXL root exit unregisters all * descendant ports and that in turn synchronizes with cxl_port_probe() */ - root = find_cxl_root(&cxlmd->dev); + root = find_cxl_root(port); /* * Now that all endpoint decoders are successfully enumerated, try to -- cgit v1.2.3