On Wed, 8 Sep 2021 22:13:26 -0700 Dan Williams <[email protected]> wrote:
> 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 <[email protected]> > Reported-by: Nathan Chancellor <[email protected]> > Reported-by: Dan Carpenter <[email protected]> > Signed-off-by: Dan Williams <[email protected]> A few minor things inline. This one was definitely a case where diff wasn't being helpful in how it chose to format things! I haven't taken the time to figure out if the device_lock() changes make complete sense as I don't understand the intent. I think they should be called out in the patch description as they seem a little non obvious. Jonathan > --- > drivers/cxl/acpi.c | 84 +++++++++++++++++++++++++---------- > drivers/cxl/core/bus.c | 114 > ++++++++++++++--------------------------------- > drivers/cxl/core/core.h | 5 -- > drivers/cxl/core/pmem.c | 7 ++- > drivers/cxl/cxl.h | 16 +++---- > 5 files changed, 106 insertions(+), 120 deletions(-) > > diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c > index 9d881eacdae5..654a80547526 100644 > --- a/drivers/cxl/acpi.c > +++ b/drivers/cxl/acpi.c > @@ -82,7 +82,6 @@ static void cxl_add_cfmws_decoders(struct device *dev, > struct cxl_decoder *cxld; > acpi_size len, cur = 0; > void *cedt_subtable; > - unsigned long flags; > int rc; > > len = acpi_cedt->length - sizeof(*acpi_cedt); > @@ -119,24 +118,36 @@ static void cxl_add_cfmws_decoders(struct device *dev, > for (i = 0; i < CFMWS_INTERLEAVE_WAYS(cfmws); i++) > target_map[i] = cfmws->interleave_targets[i]; > > - flags = cfmws_to_decoder_flags(cfmws->restrictions); > - cxld = devm_cxl_add_decoder(dev, root_port, > - CFMWS_INTERLEAVE_WAYS(cfmws), > - cfmws->base_hpa, cfmws->window_size, > - CFMWS_INTERLEAVE_WAYS(cfmws), > - CFMWS_INTERLEAVE_GRANULARITY(cfmws), > - CXL_DECODER_EXPANDER, > - flags, target_map); > - > - if (IS_ERR(cxld)) { > + cxld = cxl_decoder_alloc(root_port, > + CFMWS_INTERLEAVE_WAYS(cfmws)); > + if (IS_ERR(cxld)) > + goto next; > + > + cxld->flags = cfmws_to_decoder_flags(cfmws->restrictions); > + cxld->target_type = CXL_DECODER_EXPANDER; > + cxld->range = (struct range) { > + .start = cfmws->base_hpa, > + .end = cfmws->base_hpa + cfmws->window_size - 1, > + }; > + cxld->interleave_ways = CFMWS_INTERLEAVE_WAYS(cfmws); > + cxld->interleave_granularity = > + CFMWS_INTERLEAVE_GRANULARITY(cfmws); > + > + rc = cxl_decoder_add(dev, cxld, target_map); > + if (rc) > + put_device(&cxld->dev); > + else > + rc = cxl_decoder_autoremove(dev, cxld); > + if (rc) { > dev_err(dev, "Failed to add decoder for %#llx-%#llx\n", > cfmws->base_hpa, cfmws->base_hpa + > cfmws->window_size - 1); > - } else { > - dev_dbg(dev, "add: %s range %#llx-%#llx\n", > - dev_name(&cxld->dev), cfmws->base_hpa, > - cfmws->base_hpa + cfmws->window_size - 1); > + goto next; > } > + dev_dbg(dev, "add: %s range %#llx-%#llx\n", > + dev_name(&cxld->dev), cfmws->base_hpa, > + cfmws->base_hpa + cfmws->window_size - 1); > +next: > cur += c->length; > } > } > @@ -268,6 +279,7 @@ static int add_host_bridge_uport(struct device *match, > void *arg) > struct acpi_device *bridge = to_cxl_host_bridge(host, match); > struct acpi_pci_root *pci_root; > struct cxl_walk_context ctx; > + int single_port_map[1], rc; > struct cxl_decoder *cxld; > struct cxl_dport *dport; > struct cxl_port *port; > @@ -303,22 +315,46 @@ static int add_host_bridge_uport(struct device *match, > void *arg) > return -ENODEV; > if (ctx.error) > return ctx.error; > + if (ctx.count > 1) > + return 0; > > /* TODO: Scan CHBCR for HDM Decoder resources */ > > /* > - * In the single-port host-bridge case there are no HDM decoders > - * in the CHBCR and a 1:1 passthrough decode is implied. > + * 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. > */ > - if (ctx.count == 1) { > - cxld = devm_cxl_add_passthrough_decoder(host, port); > - if (IS_ERR(cxld)) > - return PTR_ERR(cxld); > + cxld = cxl_decoder_alloc(port, 1); > + if (IS_ERR(cxld)) > + return PTR_ERR(cxld); > + > + cxld->interleave_ways = 1; > + cxld->interleave_granularity = PAGE_SIZE; > + cxld->target_type = CXL_DECODER_EXPANDER; > + cxld->range = (struct range) { > + .start = 0, > + .end = -1, > + }; > > - dev_dbg(host, "add: %s\n", dev_name(&cxld->dev)); > - } This was previously done without taking the device lock... (see below) > + device_lock(&port->dev); > + dport = list_first_entry(&port->dports, typeof(*dport), list); > + device_unlock(&port->dev); > > - return 0; > + single_port_map[0] = dport->port_id; > + > + rc = cxl_decoder_add(host, cxld, single_port_map); > + if (rc) > + put_device(&cxld->dev); > + else > + rc = cxl_decoder_autoremove(host, cxld); > + > + if (rc == 0) > + dev_dbg(host, "add: %s\n", dev_name(&cxld->dev)); > + return rc; > } > > static int add_host_bridge_dport(struct device *match, void *arg) > diff --git a/drivers/cxl/core/bus.c b/drivers/cxl/core/bus.c > index 176bede30c55..be787685b13e 100644 > --- a/drivers/cxl/core/bus.c > +++ b/drivers/cxl/core/bus.c > @@ -455,16 +455,18 @@ 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) > + struct cxl_port *port, int *target_map) > { > int rc = 0, i; > > + if (list_empty(&port->dports)) > + return -EINVAL; > + The code before this patch did this under the device_lock() Perhaps call out the fact there is no need to do that if we don't need to? > if (!target_map) > return 0; > > device_lock(&port->dev); > - for (i = 0; i < nr_targets; i++) { > + for (i = 0; i < cxld->nr_targets; i++) { > struct cxl_dport *dport = find_dport(port, target_map[i]); > > if (!dport) { > @@ -479,27 +481,15 @@ static int decoder_populate_targets(struct device *host, > 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 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); > @@ -508,22 +498,8 @@ cxl_decoder_alloc(struct device *host, struct cxl_port > *port, int nr_targets, > 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; > + cxld->nr_targets = nr_targets; > dev = &cxld->dev; > device_initialize(dev); > device_set_pm_not_required(dev); > @@ -541,72 +517,48 @@ cxl_decoder_alloc(struct device *host, struct cxl_port > *port, int nr_targets, > 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 device *host, 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 (!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; > + return PTR_ERR(cxld); It feels like the checks here are overly paranoid. Obviously harmless, but if we get as far as cxl_decoder_add() with either cxld == NULL or IS_ERR() then something horrible is going on. I think you could reasonably drop them both. > > - 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(host, 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 > diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h > index c85b7fbad02d..e0c9aacc4e9c 100644 > --- a/drivers/cxl/core/core.h > +++ b/drivers/cxl/core/core.h > @@ -9,11 +9,6 @@ extern const struct device_type cxl_nvdimm_type; > > extern struct attribute_group cxl_base_attribute_group; > > -static inline void unregister_cxl_dev(void *dev) > -{ > - device_unregister(dev); > -} > - > struct cxl_send_command; > struct cxl_mem_query_commands; > int cxl_query_cmd(struct cxl_memdev *cxlmd, > diff --git a/drivers/cxl/core/pmem.c b/drivers/cxl/core/pmem.c > index 74be5132df1c..5032f4c1c69d 100644 > --- a/drivers/cxl/core/pmem.c > +++ b/drivers/cxl/core/pmem.c > @@ -222,6 +222,11 @@ static struct cxl_nvdimm *cxl_nvdimm_alloc(struct > cxl_memdev *cxlmd) > return cxl_nvd; > } > > +static void cxl_nvd_unregister(void *dev) > +{ > + device_unregister(dev); > +} > + > /** > * devm_cxl_add_nvdimm() - add a bridge between a cxl_memdev and an nvdimm > * @host: same host as @cxlmd > @@ -251,7 +256,7 @@ int devm_cxl_add_nvdimm(struct device *host, struct > cxl_memdev *cxlmd) > dev_dbg(host, "%s: register %s\n", dev_name(dev->parent), > dev_name(dev)); > > - return devm_add_action_or_reset(host, unregister_cxl_dev, dev); > + return devm_add_action_or_reset(host, cxl_nvd_unregister, dev); > > err: > put_device(dev); ... > @@ -286,15 +288,11 @@ int cxl_add_dport(struct cxl_port *port, struct device > *dport, int port_id, > > struct cxl_decoder *to_cxl_decoder(struct device *dev); > bool is_root_decoder(struct device *dev); > -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); > - > -struct cxl_decoder *devm_cxl_add_passthrough_decoder(struct device *host, > - struct cxl_port *port); > +struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port, int nr_targets); > +int cxl_decoder_add(struct device *host, struct cxl_decoder *cxld, > + int *target_map); > +int cxl_decoder_autoremove(struct device *host, struct cxl_decoder *cxld); > + > extern struct bus_type cxl_bus_type; > > struct cxl_driver { >
