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Message-Id: <20260116-nvmem-unbind-v1-6-7bb401ab19a8@oss.qualcomm.com>
Date: Fri, 16 Jan 2026 12:01:13 +0100
From: Bartosz Golaszewski <bartosz.golaszewski@....qualcomm.com>
To: Srinivas Kandagatla <srini@...nel.org>,
Bartosz Golaszewski <brgl@...nel.org>
Cc: linux-kernel@...r.kernel.org,
Bartosz Golaszewski <bartosz.golaszewski@....qualcomm.com>
Subject: [PATCH 6/7] nvmem: split struct nvmem_device into refcounted and
provider-owned data
Data owned by the nvmem provider must not be part of the
reference-counted struct nvmem_device. Ahead of protecting that data
with SRCU, move it into a separate structure the address of which is
stored in nvmem_device.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@....qualcomm.com>
---
drivers/nvmem/core.c | 39 ++++++++++++++++++++++++++++-----------
drivers/nvmem/internals.h | 14 +++++++++++---
2 files changed, 39 insertions(+), 14 deletions(-)
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index e3e15fa462567872718b9262a039202c6961deea..f6892af8ace52d033846f4052722289c2aa826df 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -57,25 +57,28 @@ static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
static int __nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
void *val, size_t bytes)
{
- if (!nvmem->reg_read)
+ struct nvmem_impl *impl = nvmem->impl;
+
+ if (!impl->reg_read)
return -EOPNOTSUPP;
- return nvmem->reg_read(nvmem->priv, offset, val, bytes);
+ return impl->reg_read(impl->priv, offset, val, bytes);
}
static int __nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
void *val, size_t bytes)
{
+ struct nvmem_impl *impl = nvmem->impl;
int ret, written;
- if (!nvmem->reg_write)
+ if (!impl->reg_write)
return -EOPNOTSUPP;
ret = gpiod_set_value_cansleep(nvmem->wp_gpio, 0);
if (ret)
return ret;
- written = nvmem->reg_write(nvmem->priv, offset, val, bytes);
+ written = impl->reg_write(impl->priv, offset, val, bytes);
ret = gpiod_set_value_cansleep(nvmem->wp_gpio, 1);
if (ret)
@@ -286,6 +289,8 @@ static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj,
static umode_t nvmem_bin_attr_get_umode(struct nvmem_device *nvmem)
{
+ struct nvmem_impl *impl = nvmem->impl;
+
umode_t mode = 0400;
if (!nvmem->root_only)
@@ -294,10 +299,10 @@ static umode_t nvmem_bin_attr_get_umode(struct nvmem_device *nvmem)
if (!nvmem->read_only)
mode |= 0200;
- if (!nvmem->reg_write)
+ if (!impl->reg_write)
mode &= ~0200;
- if (!nvmem->reg_read)
+ if (!impl->reg_read)
mode &= ~0444;
return mode;
@@ -328,6 +333,7 @@ static umode_t nvmem_attr_is_visible(struct kobject *kobj,
{
struct device *dev = kobj_to_dev(kobj);
struct nvmem_device *nvmem = to_nvmem_device(dev);
+ struct nvmem_impl *impl = nvmem->impl;
/*
* If the device has no .reg_write operation, do not allow
@@ -336,7 +342,7 @@ static umode_t nvmem_attr_is_visible(struct kobject *kobj,
* can be forced into read-write mode using the 'force_ro'
* attribute.
*/
- if (attr == &dev_attr_force_ro.attr && !nvmem->reg_write)
+ if (attr == &dev_attr_force_ro.attr && !impl->reg_write)
return 0; /* Attribute not visible */
return attr->mode;
@@ -537,6 +543,7 @@ static void nvmem_release(struct device *dev)
ida_free(&nvmem_ida, nvmem->id);
gpiod_put(nvmem->wp_gpio);
+ kfree(nvmem->impl);
kfree(nvmem);
}
@@ -901,6 +908,7 @@ EXPORT_SYMBOL_GPL(nvmem_layout_unregister);
struct nvmem_device *nvmem_register(const struct nvmem_config *config)
{
struct nvmem_device *nvmem;
+ struct nvmem_impl *impl;
int rval;
if (!config->dev)
@@ -913,8 +921,15 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
if (!nvmem)
return ERR_PTR(-ENOMEM);
+ impl = kzalloc_obj(*impl, GFP_KERNEL);
+ if (!impl) {
+ kfree(nvmem);
+ return ERR_PTR(-ENOMEM);
+ }
+
rval = ida_alloc(&nvmem_ida, GFP_KERNEL);
if (rval < 0) {
+ kfree(impl);
kfree(nvmem);
return ERR_PTR(rval);
}
@@ -940,6 +955,11 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
INIT_LIST_HEAD(&nvmem->cells);
nvmem->fixup_dt_cell_info = config->fixup_dt_cell_info;
+ impl->priv = config->priv;
+ impl->reg_read = config->reg_read;
+ impl->reg_write = config->reg_write;
+
+ nvmem->impl = impl;
nvmem->owner = config->owner;
if (!nvmem->owner && config->dev->driver)
nvmem->owner = config->dev->driver->owner;
@@ -947,10 +967,7 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
nvmem->word_size = config->word_size ?: 1;
nvmem->size = config->size;
nvmem->root_only = config->root_only;
- nvmem->priv = config->priv;
nvmem->type = config->type;
- nvmem->reg_read = config->reg_read;
- nvmem->reg_write = config->reg_write;
nvmem->keepout = config->keepout;
nvmem->nkeepout = config->nkeepout;
if (config->of_node)
@@ -976,7 +993,7 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
goto err_put_device;
nvmem->read_only = device_property_present(config->dev, "read-only") ||
- config->read_only || !nvmem->reg_write;
+ config->read_only || !impl->reg_write;
#ifdef CONFIG_NVMEM_SYSFS
nvmem->dev.groups = nvmem_dev_groups;
diff --git a/drivers/nvmem/internals.h b/drivers/nvmem/internals.h
index 7cbc55f40259fc4315c41979ad8bf75c36bcb056..05197074799ff3e2a6720f6552878a9e1354a5c3 100644
--- a/drivers/nvmem/internals.h
+++ b/drivers/nvmem/internals.h
@@ -7,9 +7,20 @@
#include <linux/nvmem-consumer.h>
#include <linux/nvmem-provider.h>
+/*
+ * Holds data owned by the provider of the nvmem implementation. This goes
+ * away immediately the moment nvmem_unregister() is called.
+ */
+struct nvmem_impl {
+ nvmem_reg_read_t reg_read;
+ nvmem_reg_write_t reg_write;
+ void *priv;
+};
+
struct nvmem_device {
struct module *owner;
struct device dev;
+ struct nvmem_impl *impl;
int stride;
int word_size;
int id;
@@ -26,11 +37,8 @@ struct nvmem_device {
struct nvmem_cell_info *cell);
const struct nvmem_keepout *keepout;
unsigned int nkeepout;
- nvmem_reg_read_t reg_read;
- nvmem_reg_write_t reg_write;
struct gpio_desc *wp_gpio;
struct nvmem_layout *layout;
- void *priv;
bool sysfs_cells_populated;
};
--
2.47.3
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