From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean Delvare Subject: Re: [PATCH] i2c: do not use device name after device_unregister Date: Wed, 13 Jan 2010 11:25:15 +0100 Message-ID: <20100113112515.3c73ceee@hyperion.delvare> References: <1263332203-5542-1-git-send-email-cascardo@holoscopio.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <1263332203-5542-1-git-send-email-cascardo@holoscopio.com> Sender: linux-kernel-owner@vger.kernel.org To: Thadeu Lima de Souza Cascardo Cc: linux-i2c@vger.kernel.org, "Ben Dooks (embedded platforms)" , linux-kernel@vger.kernel.org List-Id: linux-i2c@vger.kernel.org Hi Thadeu, On Tue, 12 Jan 2010 19:36:43 -0200, Thadeu Lima de Souza Cascardo wrote= : > dev_dbg outputs dev_name, which is released with device_unregister. T= his bug > resulted in output like this: >=20 > [ 7860.470713] i2c Xy2=EF=BF=BD0: adapter [SMBus I801 adapter at 1880= ] unregistered >=20 > The right output would be: > [ 60.639233] i2c i2c-0: adapter [SMBus I801 adapter at 1880] unregi= stered I can't reproduce this bug. Do you have a specific memory poisoning option enabled by any chance? And which kernel version are you running exactly? >=20 > Signed-off-by: Thadeu Lima de Souza Cascardo > --- > drivers/i2c/i2c-core.c | 5 +++-- > 1 files changed, 3 insertions(+), 2 deletions(-) >=20 > diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c > index 0ac2f90..d5db0f4 100644 > --- a/drivers/i2c/i2c-core.c > +++ b/drivers/i2c/i2c-core.c > @@ -843,6 +843,9 @@ int i2c_del_adapter(struct i2c_adapter *adap) > adap->dev.parent); > #endif > =20 > + /* device name is gone after device_unregister */ > + dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name); > + > /* clean up the sysfs representation */ > init_completion(&adap->dev_released); > device_unregister(&adap->dev); > @@ -855,8 +858,6 @@ int i2c_del_adapter(struct i2c_adapter *adap) > idr_remove(&i2c_adapter_idr, adap->nr); > mutex_unlock(&core_lock); > =20 > - dev_dbg(&adap->dev, "adapter [%s] unregistered\n", adap->name); > - > /* Clear the device structure in case this adapter is ever going to= be > added again */ > memset(&adap->dev, 0, sizeof(adap->dev)); The device structure is embedded in struct i2c_adapter, so its memory can't be reused before the i2c_adapter itself is freed, which can't happen before the end of function i2c_del_adapter(). Until recently, the device name was embedded in the device structure so the code above was fine. But apparently this changed some 9 months ago... --=20 Jean Delvare