On 17.05.23 11:20, Christian Gabriel wrote:

From: "Russell King (Oracle)" rmk+kernel@armlinux.org.uk

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The occurs because the nvmem core registration code violates one of the fundamental principles of kernel programming: do not publish data structures before their setup is complete.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@vger.kernel.org Fixes: eace75cfdcf7 ("nvmem: Add a simple NVMEM framework for nvmem providers") Signed-off-by: Russell King (Oracle) rmk+kernel@armlinux.org.uk Signed-off-by: Srinivas Kandagatla srinivas.kandagatla@linaro.org

(cherry picked from ab3428cfd9aa2f3463ee4b2909b5bb2193bd0c4a)

Signed-off-by: Christian Gabriel christian.gabriel@linutronix.de

Please add the (cherry-picked line above your SoB)

Than add my: Reviewed-by: Steffen Kothe steffen.kothe@linutronix.de

---

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);

Mit freundlichen Grüßen / Kind Regards