The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
Possible dependencies:
ab3428cfd9aa ("nvmem: core: fix registration vs use race")
560181d3ace6 ("nvmem: core: fix cleanup after dev_set_name()")
569653f022a2 ("nvmem: core: remove nvmem_config wp_gpio")
3bd747c7ea13 ("nvmem: core: initialise nvmem->id early")
5544e90c8126 ("nvmem: core: add error handling for dev_set_name")
bd1244561fa2 ("nvmem: core: Fix memleak in nvmem_register()")
f6c052afe6f8 ("nvmem: core: Fix a conflict between MTD and NVMEM on wp-gpios property")
de0534df9347 ("nvmem: core: fix error handling while validating keepout regions")
1333a6779501 ("nvmem: core: allow specifying of_node")
fd3bb8f54a88 ("nvmem: core: Add support for keepout regions")
1eb51d6a4fce ("nvmem: switch to simpler IDA interface")
731aa3fae813 ("nvmem: core: add support to auto devid")
b96fc5416b09 ("nvmem: ensure sysfs writes handle write-protect pin")
844003052719 ("nvmem: core: remove nvmem_sysfs_get_groups()")
664f0549380c ("nvmem: core: use is_bin_visible for permissions")
f60442ddc40c ("nvmem: core: use device_register and device_unregister")
e6de179d7a88 ("nvmem: core: add root_only member to nvmem device struct")
3c91ef69a3e9 ("nvmem: check for NULL reg_read and reg_write before dereferencing")
a9c3766cb19c ("nvmem: release the write-protect pin")
f7d8d7dcd978 ("nvmem: fix memory leak in error path")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From ab3428cfd9aa2f3463ee4b2909b5bb2193bd0c4a Mon Sep 17 00:00:00 2001
From: "Russell King (Oracle)" <rmk+kernel@xxxxxxxxxxxxxxx>
Date: Fri, 27 Jan 2023 10:40:11 +0000
Subject: [PATCH] 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fundamental principles of kernel programming: do not publish data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@xxxxxxxxxxxxxxx
Signed-off-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230127104015.23839-7-srinivas.kandagatla@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
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 @@ 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);
