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Mon, 23 Sep 2019 12:11:13 -0700 (PDT) Date: Mon, 23 Sep 2019 12:11:11 -0700 From: Matthias Kaehlcke To: Leonard Crestez Subject: Re: [PATCH v6 2/6] PM / devfreq: Move more initialization before registration Message-ID: <20190923191111.GE133864@google.com> References: <0ad496507cd7e6731e46249b1499dfdebe205c16.1569252537.git.leonard.crestez@nxp.com> <20190923181057.GY133864@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190923_121114_589529_1E6DF987 X-CRM114-Status: GOOD ( 22.92 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Artur =?utf-8?B?xZp3aWdvxYQ=?= , Abel Vesa , Saravana Kannan , "linux-pm@vger.kernel.org" , Viresh Kumar , dl-linux-imx , Krzysztof Kozlowski , Lukasz Luba , Chanwoo Choi , Kyungmin Park , MyungJoo Ham , Alexandre Bailon , Georgi Djakov , "linux-arm-kernel@lists.infradead.org" , Jacky Bai Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Sep 23, 2019 at 06:56:28PM +0000, Leonard Crestez wrote: > On 23.09.2019 21:11, Matthias Kaehlcke wrote: > > On Mon, Sep 23, 2019 at 06:51:05PM +0300, Leonard Crestez wrote: > >> In general it is a better to initialize an object before making it > >> accessible externally (through device_register). > >> > >> This makes it possible to avoid relying on locking a partially > >> initialized object. > >> > >> Signed-off-by: Leonard Crestez > >> --- > >> drivers/devfreq/devfreq.c | 43 +++++++++++++++++++++++---------------- > >> 1 file changed, 25 insertions(+), 18 deletions(-) > >> > >> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c > >> index 323d43315d1e..b4d2bfebb140 100644 > >> --- a/drivers/devfreq/devfreq.c > >> +++ b/drivers/devfreq/devfreq.c > >> @@ -587,10 +587,12 @@ static void devfreq_dev_release(struct device *dev) > >> mutex_unlock(&devfreq_list_lock); > >> > >> if (devfreq->profile->exit) > >> devfreq->profile->exit(devfreq->dev.parent); > >> > >> + kfree(devfreq->time_in_state); > >> + kfree(devfreq->trans_table); > >> mutex_destroy(&devfreq->lock); > >> kfree(devfreq); > >> } > >> > >> /** > >> @@ -670,44 +672,43 @@ struct devfreq *devfreq_add_device(struct device *dev, > >> devfreq->max_freq = devfreq->scaling_max_freq; > >> > >> devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev); > >> atomic_set(&devfreq->suspend_count, 0); > >> > >> - dev_set_name(&devfreq->dev, "devfreq%d", > >> - atomic_inc_return(&devfreq_no)); > >> - err = device_register(&devfreq->dev); > >> - if (err) { > >> - mutex_unlock(&devfreq->lock); > >> - put_device(&devfreq->dev); > >> - goto err_out; > >> - } > >> - > >> - devfreq->trans_table = devm_kzalloc(&devfreq->dev, > >> + devfreq->trans_table = kzalloc( > >> array3_size(sizeof(unsigned int), > >> devfreq->profile->max_state, > >> devfreq->profile->max_state), > >> GFP_KERNEL); > >> if (!devfreq->trans_table) { > >> mutex_unlock(&devfreq->lock); > >> err = -ENOMEM; > >> - goto err_devfreq; > >> + goto err_dev; > >> } > >> > >> - devfreq->time_in_state = devm_kcalloc(&devfreq->dev, > >> - devfreq->profile->max_state, > >> - sizeof(unsigned long), > >> - GFP_KERNEL); > >> + devfreq->time_in_state = kcalloc(devfreq->profile->max_state, > >> + sizeof(unsigned long), > >> + GFP_KERNEL); > >> if (!devfreq->time_in_state) { > >> mutex_unlock(&devfreq->lock); > >> err = -ENOMEM; > >> - goto err_devfreq; > >> + goto err_dev; > >> } > >> > >> devfreq->last_stat_updated = jiffies; > >> > >> srcu_init_notifier_head(&devfreq->transition_notifier_list); > >> > >> + dev_set_name(&devfreq->dev, "devfreq%d", > >> + atomic_inc_return(&devfreq_no)); > >> + err = device_register(&devfreq->dev); > >> + if (err) { > >> + mutex_unlock(&devfreq->lock); > >> + put_device(&devfreq->dev); > >> + goto err_out; > > > > As per my comment on v5 I think the goto needs to go to 'err_dev'. The > > device registration failed, hence devfreq_dev_release() won't be > > called to free allocated memory. > > This code is not modified in the patch, it only shows up as +added > because diff got confused but there is an identical -removed chunk > higher up. > > The device_register documentation mentions the following: > > * NOTE: _Never_ directly free @dev after calling this function, even > * if it returned an error! Always use put_device() to give up the > * reference initialized in this function instead. > > Cleanup path then goes like this (from a hacked error in device_add): > dump_stack+0xdc/0x144 > > > devfreq_dev_release+0x38/0xc0 > > > device_release+0x34/0x90 > > > kobject_put+0x8c/0x1f0 > > > put_device+0x24/0x30 > > > devfreq_add_device+0x540/0x570 > > > devm_devfreq_add_device+0x60/0xd0 > > > imx_ddrc_probe+0x35c/0x4c8 Good to know, thanks for the pointer! > Can I add your "Reviewed-By" for the rest of the series if I fix the nits? By now you should have it for most patches. For this one: Reviewed-by: Matthias Kaehlcke There is one doubt I have left on "PM / devfreq: Add PM QoS support" that I posted on v5: "IIUC you rely on the notifiers being removed by devfreq_dev_release(). Does dev_pm_qos_remove_notifier() behave gracefully if the notifier is not initialized/added or do we need to use BLOCKING_NOTIFIER_INIT() or similar?" Could you clarify this replying to the thread? Besides that and the nits (which are optional to fix) the patch looks good to me. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel