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Subject[PATCH] power: supply: sysfs: prevent endless uevent loop with CONFIG_POWER_SUPPLY_DEBUG
Date
Fix a similar endless event loop as was done in commit 8dcf32175b4e
("i2c: prevent endless uevent loop with CONFIG_I2C_DEBUG_CORE"):

The culprit is the dev_dbg printk in the i2c uevent handler. If
this is activated (for instance by CONFIG_I2C_DEBUG_CORE) it results
in an endless loop with systemd-journald.

This happens if user-space scans the system log and reads the uevent
file to get information about a newly created device, which seems
fair use to me. Unfortunately reading the "uevent" file uses the
same function that runs for creating the uevent for a new device,
generating the next syslog entry

Both CONFIG_I2C_DEBUG_CORE and CONFIG_POWER_SUPPLY_DEBUG were reported
in https://bugs.freedesktop.org/show_bug.cgi?id=76886 but only former
seems to have been fixed. Change debug prints to use pr_debug insted
to resolve the issue.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Chris Healy <cphealy@gmail.com>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
drivers/power/supply/power_supply_sysfs.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
index dce24f596160..5e91946731fd 100644
--- a/drivers/power/supply/power_supply_sysfs.c
+++ b/drivers/power/supply/power_supply_sysfs.c
@@ -383,14 +383,14 @@ int power_supply_uevent(struct device *dev, struct kobj_uevent_env *env)
char *prop_buf;
char *attrname;

- dev_dbg(dev, "uevent\n");
+ pr_debug("%s: uevent\n", dev_name(dev));

if (!psy || !psy->desc) {
dev_dbg(dev, "No power supply yet\n");
return ret;
}

- dev_dbg(dev, "POWER_SUPPLY_NAME=%s\n", psy->desc->name);
+ pr_debug("%s: POWER_SUPPLY_NAME=%s\n", dev_name(dev), psy->desc->name);

ret = add_uevent_var(env, "POWER_SUPPLY_NAME=%s", psy->desc->name);
if (ret)
@@ -427,7 +427,8 @@ int power_supply_uevent(struct device *dev, struct kobj_uevent_env *env)
goto out;
}

- dev_dbg(dev, "prop %s=%s\n", attrname, prop_buf);
+ pr_debug("%s: prop %s=%s\n", dev_name(dev), attrname,
+ prop_buf);

ret = add_uevent_var(env, "POWER_SUPPLY_%s=%s", attrname, prop_buf);
kfree(attrname);
--
2.20.1
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