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[77.136.64.85]) by smtp.googlemail.com with ESMTPSA id h16sm6239850wrb.62.2018.11.25.01.41.45 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 25 Nov 2018 01:41:45 -0800 (PST) Subject: Re: [PATCH] clocksource/drivers/integrator-ap: add missing of_node_put() To: Frank Lee Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org References: <20181122152331.25739-1-tiny.windzz@gmail.com> <97b95b60-8420-bad9-4d2c-6baee749b90f@linaro.org> From: Daniel Lezcano Message-ID: Date: Sun, 25 Nov 2018 10:41:44 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25/11/2018 05:25, Frank Lee wrote: > On Sun, Nov 25, 2018 at 3:49 AM Daniel Lezcano > wrote: >> >> On 24/11/2018 15:58, Frank Lee wrote: >>> On Thu, Nov 22, 2018 at 11:23 PM Yangtao Li wrote: >>>> >>>> of_find_node_by_path() acquires a reference to the node >>>> returned by it and that reference needs to be dropped by its caller. >>>> integrator_ap_timer_init_of() doesn't do that, so fix it. >>>> >>>> Signed-off-by: Yangtao Li >>>> --- >>>> drivers/clocksource/timer-integrator-ap.c | 20 ++++++++++++++------ >>>> 1 file changed, 14 insertions(+), 6 deletions(-) >>>> >>>> diff --git a/drivers/clocksource/timer-integrator-ap.c b/drivers/clocksource/timer-integrator-ap.c >>>> index 76e526f58620..1f04069470bb 100644 >>>> --- a/drivers/clocksource/timer-integrator-ap.c >>>> +++ b/drivers/clocksource/timer-integrator-ap.c >>>> @@ -177,7 +177,7 @@ static int __init integrator_ap_timer_init_of(struct device_node *node) >>>> { >>>> const char *path; >>>> void __iomem *base; >>>> - int err; >>>> + int err,rc = 0; >>>> int irq; >>>> struct clk *clk; >>>> unsigned long rate; >>>> @@ -210,26 +210,34 @@ static int __init integrator_ap_timer_init_of(struct device_node *node) >>>> "arm,timer-secondary", &path); >>>> if (err) { >>>> pr_warn("Failed to read property\n"); >>>> - return err; >>>> + rc = err; >>>> + goto out_put_pri_node; >>>> } >>>> >>>> >>>> sec_node = of_find_node_by_path(path); >>>> >>>> - if (node == pri_node) >>>> + if (node == pri_node){ >>>> /* The primary timer lacks IRQ, use as clocksource */ >>>> - return integrator_clocksource_init(rate, base); >>>> + rc = integrator_clocksource_init(rate, base); >>>> + goto out; >>>> + } >>>> >>>> if (node == sec_node) { >>>> /* The secondary timer will drive the clock event */ >>>> irq = irq_of_parse_and_map(node, 0); >>>> - return integrator_clockevent_init(rate, base, irq); >>>> + rc = integrator_clockevent_init(rate, base, irq); >>>> + goto out; >>>> } >>>> >>>> pr_info("Timer @%p unused\n", base); >>>> clk_disable_unprepare(clk); >>>> +out: >>>> + of_node_put(sec_node); >>>> +out_put_pri_node: >>>> + of_node_put(pri_node); >>>> >>>> - return 0; >>>> + return rc; >>>> } >>>> >>>> TIMER_OF_DECLARE(integrator_ap_timer, "arm,integrator-timer", >>>> -- >>>> 2.17.0 >>>> >>> Hi Daniel： >>> >>> How about this? >> >> Hi, >> >> I think there is a simpler fix. The pri_node and the sec_node are used >> as an identifier to compare against the current node, we can directly >> drop the refcount after getting the node from path as it is not used as >> pointer. In addition, a single variable is needed, so we end up with a >> fix like that. >> >> alias_node = of_find_node_by_path(path); >> of_node_put(alias_node); >> if (node == alias_node) >> return integrator_clocksource_init(rate, base); > > Daniel, > > OK,I will simplify it like you said.Although I think of_node_put > should be called > after we don't use node. Except I'm missing something, we don't use the alias_node at any time. The node itself has already a refcount which gives us the guarantee it is valid. I agree it can appear a bit strange to put the node right after getting it but in our case the alias_node is used as an ID, not a pointer, so it is fine. -- Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog