Re: [PATCH v4 1/1] nvmem: Add support for write-only instances
From: Srinivas Kandagatla
Date: Wed Mar 18 2020 - 05:29:07 EST
On 18/03/2020 09:17, Nicholas Johnson wrote:
On Tue, Mar 17, 2020 at 02:35:44PM +0000, Srinivas Kandagatla wrote:
On 17/03/2020 01:01, Nicholas Johnson wrote:
There is at least one real-world use-case for write-only nvmem
instances. Refer to 03cd45d2e219 ("thunderbolt: Prevent crash if
non-active NVMem file is read").
Add support for write-only nvmem instances by adding attrs for 0200.
Change nvmem_register() to abort if NULL group is returned from
nvmem_sysfs_get_groups().
Return NULL from nvmem_sysfs_get_groups() in invalid cases.
Signed-off-by: Nicholas Johnson <nicholas.johnson-opensource@xxxxxxxxxxxxxx>
---
drivers/nvmem/core.c | 9 ++++--
drivers/nvmem/nvmem-sysfs.c | 56 +++++++++++++++++++++++++++++++------
2 files changed, 54 insertions(+), 11 deletions(-)
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index ef326f243..95ea9a3b2 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -373,6 +373,12 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
nvmem->type = config->type;
nvmem->reg_read = config->reg_read;
nvmem->reg_write = config->reg_write;
+ nvmem->dev.groups = nvmem_sysfs_get_groups(nvmem, config);
+ if (!nvmem->dev.groups) {
+ kfree(nvmem);
+ return ERR_PTR(-EINVAL);
When I meant leaking here, not just memory but other resources like idr and
gpio.
You should do something like this:
if (!nvmem->dev.groups) {
ida_simple_remove(&nvmem_ida, nvmem->id);
gpiod_put(nvmem->wp_gpio);
kfree(nvmem);
return ERR_PTR(-EINVAL);
}
Thanks. I am guessing these are called indirectly when there are other
failures (goto err_*). We have ida_simple_remove() in nvmem_release()
but I cannot find gpiod_put anywhere in drivers/nvmem.
Because you are returning here before device intialize, you would need
to do the cleanup.
Latest changes are available in linux-next or
https://git.kernel.org/pub/scm/linux/kernel/git/srini/nvmem.git/tree/drivers/nvmem/core.c?h=for-next
Please rebase your patches on top of this branch, so its easy for me to
apply without conflicts.
--srini
+ }
+
if (!config->no_of_node)
nvmem->dev.of_node = config->dev->of_node;
@@ -387,8 +393,6 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
nvmem->read_only = device_property_present(config->dev, "read-only") ||
config->read_only || !nvmem->reg_write;
- nvmem->dev.groups = nvmem_sysfs_get_groups(nvmem, config);
-
device_initialize(&nvmem->dev);
dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
@@ -430,7 +434,6 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
device_del(&nvmem->dev);
err_put_device:
put_device(&nvmem->dev);
-
unnecessary cleanup here!
Sorry, I let this mistake slip, despite checking my work.
Other than that every thing looks good to me!
--srini
Cheers,
Nicholas
return ERR_PTR(rval);
}
EXPORT_SYMBOL_GPL(nvmem_register);
diff --git a/drivers/nvmem/nvmem-sysfs.c b/drivers/nvmem/nvmem-sysfs.c
index 9e0c429cd..4ceac8680 100644
--- a/drivers/nvmem/nvmem-sysfs.c
+++ b/drivers/nvmem/nvmem-sysfs.c
@@ -196,16 +196,49 @@ static const struct attribute_group *nvmem_ro_root_dev_groups[] = {
NULL,
};
+/* write only permission, root only */
+static struct bin_attribute bin_attr_wo_root_nvmem = {
+ .attr = {
+ .name = "nvmem",
+ .mode = 0200,
+ },
+ .write = bin_attr_nvmem_write,
+};
+
+static struct bin_attribute *nvmem_bin_wo_root_attributes[] = {
+ &bin_attr_wo_root_nvmem,
+ NULL,
+};
+
+static const struct attribute_group nvmem_bin_wo_root_group = {
+ .bin_attrs = nvmem_bin_wo_root_attributes,
+ .attrs = nvmem_attrs,
+};
+
+static const struct attribute_group *nvmem_wo_root_dev_groups[] = {
+ &nvmem_bin_wo_root_group,
+ NULL,
+};
+
const struct attribute_group **nvmem_sysfs_get_groups(
struct nvmem_device *nvmem,
const struct nvmem_config *config)
{
- if (config->root_only)
- return nvmem->read_only ?
- nvmem_ro_root_dev_groups :
- nvmem_rw_root_dev_groups;
+ /* Read-only */
+ if (nvmem->reg_read && (!nvmem->reg_write || nvmem->read_only))
+ return config->root_only ?
+ nvmem_ro_root_dev_groups : nvmem_ro_dev_groups;
+
+ /* Read-write */
+ if (nvmem->reg_read && nvmem->reg_write && !nvmem->read_only)
+ return config->root_only ?
+ nvmem_rw_root_dev_groups : nvmem_rw_dev_groups;
+
+ /* Write-only, do not honour request for global writable entry */
+ if (!nvmem->reg_read && nvmem->reg_write && !nvmem->read_only)
+ return config->root_only ? nvmem_wo_root_dev_groups : NULL;
- return nvmem->read_only ? nvmem_ro_dev_groups : nvmem_rw_dev_groups;
+ return NULL;
}
/*
@@ -224,17 +257,24 @@ int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
if (!config->base_dev)
return -EINVAL;
- if (nvmem->read_only) {
+ if (nvmem->reg_read && (!nvmem->reg_write || nvmem->read_only)) {
if (config->root_only)
nvmem->eeprom = bin_attr_ro_root_nvmem;
else
nvmem->eeprom = bin_attr_ro_nvmem;
- } else {
+ } else if (!nvmem->reg_read && nvmem->reg_write && !nvmem->read_only) {
+ if (config->root_only)
+ nvmem->eeprom = bin_attr_wo_root_nvmem;
+ else
+ return -EINVAL;
+ } else if (nvmem->reg_read && nvmem->reg_write && !nvmem->read_only) {
if (config->root_only)
nvmem->eeprom = bin_attr_rw_root_nvmem;
else
nvmem->eeprom = bin_attr_rw_nvmem;
- }
+ } else
+ return -EINVAL;
+
nvmem->eeprom.attr.name = "eeprom";
nvmem->eeprom.size = nvmem->size;
#ifdef CONFIG_DEBUG_LOCK_ALLOC