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gpio: sim: lock up configfs that an instantiated device depends on

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BugLink: https://bugs.launchpad.net/bugs/2107449

[ Upstream commit 8bd76b3d3f3af7ac2898b6a27ad90c444fec418f ]

Once a sim device is instantiated and actively used, allowing rmdir for
its configfs serves no purpose and can be confusing. Effectively,
arbitrary users start depending on its existence.

Make the subsystem itself depend on the configfs entry for a sim device
while it is in active use.

Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Link: https://lore.kernel.org/r/20250103141829.430662-5-koichiro.den@canonical.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[koichiroden: adjusted context due to the missing commit:
11498d99008f ("gpio: sim: add lockdep asserts")]
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
This commit is contained in:
Koichiro Den
2025-01-03 23:18:29 +09:00
committed by Stefan Bader
parent f74fe113f3
commit a538e6eb0c
1 changed files with 41 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/gpio/gpio-sim.c
+41 -7
View File
@@ -1009,6 +1009,30 @@ static void gpio_sim_device_deactivate_unlocked(struct gpio_sim_device *dev)
dev->pdev = NULL;
}
static void
gpio_sim_device_lockup_configfs(struct gpio_sim_device *dev, bool lock)
{
struct configfs_subsystem *subsys = dev->group.cg_subsys;
struct gpio_sim_bank *bank;
struct gpio_sim_line *line;
/*
* The device only needs to depend on leaf line entries. This is
* sufficient to lock up all the configfs entries that the
* instantiated, alive device depends on.
*/
list_for_each_entry(bank, &dev->bank_list, siblings) {
list_for_each_entry(line, &bank->line_list, siblings) {
if (lock)
WARN_ON(configfs_depend_item_unlocked(
subsys, &line->group.cg_item));
else
configfs_undepend_item_unlocked(
&line->group.cg_item);
}
}
}
static ssize_t
gpio_sim_device_config_live_store(struct config_item *item,
const char *page, size_t count)
@@ -1021,14 +1045,24 @@ gpio_sim_device_config_live_store(struct config_item *item,
if (ret)
return ret;
guard(mutex)(&dev->lock);
if (live)
gpio_sim_device_lockup_configfs(dev, true);
if (live == gpio_sim_device_is_live_unlocked(dev))
ret = -EPERM;
else if (live)
ret = gpio_sim_device_activate_unlocked(dev);
else
gpio_sim_device_deactivate_unlocked(dev);
scoped_guard(mutex, &dev->lock) {
if (live == gpio_sim_device_is_live_unlocked(dev))
ret = -EPERM;
else if (live)
ret = gpio_sim_device_activate_unlocked(dev);
else
gpio_sim_device_deactivate_unlocked(dev);
}
/*
* Undepend is required only if device disablement (live == 0)
* succeeds or if device enablement (live == 1) fails.
*/
if (live == !!ret)
gpio_sim_device_lockup_configfs(dev, false);
return ret ?: count;
}