From: "Russell King (Oracle)" <rmk+kernel@xxxxxxxxxxxxxxx>
The i.MX6 CPU frequency driver sometimes fails to register at boot time
due to nvmem_cell_read_u32() sporadically returning -ENOENT.
This happens because there is a window where __nvmem_device_get() in
of_nvmem_cell_get() is able to return the nvmem device, but as cells
have been setup, nvmem_find_cell_entry_by_node() returns NULL.
The occurs because the nvmem core registration code violates one of the
fundamental principles of kernel programming: do not publish data
structures before their setup is complete.
Fix this by making nvmem core code conform with this principle.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: eace75cfdcf7 ("nvmem: Add a simple NVMEM framework for nvmem providers")
Signed-off-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
Signed-off-by: Christian Gabriel <christian.gabriel@xxxxxxxxxxxxx>
---
drivers/nvmem/core.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 84f4078216a3..6aa8947c4d57 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -418,16 +418,10 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
device_initialize(&nvmem->dev);
- dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
-
- rval = device_add(&nvmem->dev);
- if (rval)
- goto err_put_device;
-
if (config->compat) {
rval = nvmem_sysfs_setup_compat(nvmem, config);
if (rval)
- goto err_device_del;
+ goto err_put_device;
}
if (config->cells) {
@@ -444,6 +438,12 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
if (rval)
goto err_remove_cells;
+ dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
+
+ rval = device_add(&nvmem->dev);
+ if (rval)
+ goto err_remove_cells;
+
blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
return nvmem;
@@ -453,8 +453,6 @@ 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);
--
2.30.2
