On 03/01/2023 11:44, Hector Martin wrote:
nvmem_register() currently registers the device before adding the nvmem cells, which creates a race window where consumers may find the nvmem device (and not get PROBE_DEFERred), but then fail to find the cells and error out.
Move device registration to the end of nvmem_register(), to close the race.
Observed when the stars line up on Apple Silicon machines with the (not yet upstream, but trivial) spmi nvmem driver and the macsmc-rtc client:
[ 0.487375] macsmc-rtc macsmc-rtc: error -ENOENT: Failed to get rtc_offset NVMEM cell
Fixes: eace75cfdcf7 ("nvmem: Add a simple NVMEM framework for nvmem providers") Cc: stable@vger.kernel.org Reviewed-by: Eric Curtin ecurtin@redhat.com Signed-off-by: Hector Martin marcan@marcan.st
What has changed since v1?
drivers/nvmem/core.c | 32 +++++++++++++++++--------------- 1 file changed, 17 insertions(+), 15 deletions(-)
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index 321d7d63e068..606f428d6292 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -822,11 +822,8 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) break; }
- if (rval) {
ida_free(&nvmem_ida, nvmem->id);kfree(nvmem);return ERR_PTR(rval);- }
- if (rval)
goto err_gpiod_put;
Why was gpiod changes added to this patch, that should be a separate patch/discussion, as this is not relevant to the issue that you are reporting.
nvmem->read_only = device_property_present(config->dev, "read-only") || config->read_only || !nvmem->reg_write; @@ -837,20 +834,16 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
- rval = device_register(&nvmem->dev);
- if (rval)
goto err_put_device;- if (nvmem->nkeepout) { rval = nvmem_validate_keepouts(nvmem); if (rval)
goto err_device_del;
goto err_gpiod_put;}
if (config->compat) { rval = nvmem_sysfs_setup_compat(nvmem, config); if (rval)
goto err_device_del;
goto err_gpiod_put;}
if (config->cells) {
@@ -867,6 +860,15 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) if (rval) goto err_remove_cells;
rval = device_register(&nvmem->dev);
if (rval) {
nvmem_device_remove_all_cells(nvmem);if (config->compat)nvmem_sysfs_remove_compat(nvmem, config);put_device(&nvmem->dev);return ERR_PTR(rval);}
blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
return nvmem;
@@ -876,10 +878,10 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) err_teardown_compat: if (config->compat) nvmem_sysfs_remove_compat(nvmem, config); -err_device_del:
- device_del(&nvmem->dev);
-err_put_device:
- put_device(&nvmem->dev);
+err_gpiod_put:
gpiod_put(nvmem->wp_gpio);
ida_free(&nvmem_ida, nvmem->id);
kfree(nvmem);
return ERR_PTR(rval); }
-- 2.35.1