diff options
| author | Russell King (Oracle) <rmk+kernel@armlinux.org.uk> | 2023-01-27 10:40:11 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-01-28 14:36:29 +0100 |
| commit | ab3428cfd9aa2f3463ee4b2909b5bb2193bd0c4a (patch) | |
| tree | 6bf1715c7bd64f86793fd75d26b04d4fcc3ce489 /drivers/nvmem | |
| parent | 560181d3ace61825f4ca9dd3481d6c0ee6709fa8 (diff) | |
nvmem: core: fix registration vs use race
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fundamental principles of kernel programming: do not publish data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.
Fixes: eace75cfdcf7 ("nvmem: Add a simple NVMEM framework for nvmem providers")
Cc: stable@vger.kernel.org
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20230127104015.23839-7-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/nvmem')
| -rw-r--r-- | drivers/nvmem/core.c | 18 |
1 files changed, 8 insertions, 10 deletions
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c index ac77a019aed7..e92c6f1aadbb 100644 --- a/drivers/nvmem/core.c +++ b/drivers/nvmem/core.c @@ -832,22 +832,16 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config) nvmem->dev.groups = nvmem_dev_groups; #endif - dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name); - - rval = device_add(&nvmem->dev); - if (rval) - goto err_put_device; - if (nvmem->nkeepout) { rval = nvmem_validate_keepouts(nvmem); if (rval) - goto err_device_del; + 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) { @@ -864,6 +858,12 @@ 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; @@ -873,8 +873,6 @@ err_remove_cells: 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); |