linux-kernel - [PATCH v2] power: supply: sysfs: prevent endless uevent loop with CONFIG_POWER_SUPPLY

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Message-Id: <20190424071610.22688-1-andrew.smirnov@gmail.com>
Date:   Wed, 24 Apr 2019 00:16:10 -0700
From:   Andrey Smirnov <andrew.smirnov@...il.com>
To:     linux-pm@...r.kernel.org
Cc:     Andrey Smirnov <andrew.smirnov@...il.com>,
        Chris Healy <cphealy@...il.com>,
        Sebastian Reichel <sre@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2] power: supply: sysfs: prevent endless uevent loop with CONFIG_POWER_SUPPLY_DEBUG

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. Drop debug prints as it was done in I2C
subsystem to resolve the issue.

Signed-off-by: Andrey Smirnov <andrew.smirnov@...il.com>
Cc: Chris Healy <cphealy@...il.com>
Cc: Sebastian Reichel <sre@...nel.org>
Cc: linux-pm@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
---

Changes since [v1]:

    - Converted the patch to drop debug print statements
    
[v1] lore.kernel.org/lkml/20190405073020.10361-1-andrew.smirnov@...il.com

 drivers/power/supply/power_supply_sysfs.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/power/supply/power_supply_sysfs.c b/drivers/power/supply/power_supply_sysfs.c
index dce24f596160..5358a80d854f 100644
--- a/drivers/power/supply/power_supply_sysfs.c
+++ b/drivers/power/supply/power_supply_sysfs.c
@@ -383,15 +383,11 @@ int power_supply_uevent(struct device *dev, struct kobj_uevent_env *env)
 	char *prop_buf;
 	char *attrname;
 
-	dev_dbg(dev, "uevent\n");
-
 	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);
-
 	ret = add_uevent_var(env, "POWER_SUPPLY_NAME=%s", psy->desc->name);
 	if (ret)
 		return ret;
@@ -427,8 +423,6 @@ int power_supply_uevent(struct device *dev, struct kobj_uevent_env *env)
 			goto out;
 		}
 
-		dev_dbg(dev, "prop %s=%s\n", attrname, prop_buf);
-
 		ret = add_uevent_var(env, "POWER_SUPPLY_%s=%s", attrname, prop_buf);
 		kfree(attrname);
 		if (ret)
-- 
2.20.1