Message ID | 20190405073020.10361-1-andrew.smirnov@gmail.com (mailing list archive) |
---|---|
State | Not Applicable, archived |
Headers | show |
Series | power: supply: sysfs: prevent endless uevent loop with CONFIG_POWER_SUPPLY_DEBUG | expand |
Hi, On Fri, Apr 05, 2019 at 12:30:20AM -0700, Andrey Smirnov wrote: > 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 > --- I think we should just drop these debug messages, just like I2C did. They don't offer any useful information considering the info is already exposed to userspace via the uevent. -- Sebastian > 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 >
On Wed, Apr 17, 2019 at 7:35 PM Sebastian Reichel <sre@kernel.org> wrote: > > Hi, > > On Fri, Apr 05, 2019 at 12:30:20AM -0700, Andrey Smirnov wrote: > > 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 > > --- > > I think we should just drop these debug messages, just like I2C did. > They don't offer any useful information considering the info is already > exposed to userspace via the uevent. OK, sounds good, will do in v2. Thanks, Andrey Smirnov
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);
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(-)