On Sat, 17 Feb 2024 12:29:32 -0800 Dan Williams <dan.j.williams@xxxxxxxxx> 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@xxxxxxxxxxxxxxx> > Cc: Breno Leitao <leitao@xxxxxxxxxx> > Cc: Alison Schofield <alison.schofield@xxxxxxxxx> > Cc: Vishal Verma <vishal.l.verma@xxxxxxxxx> > Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx> 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) > { > >