Linux-PM Archive on lore.kernel.org
 help / color / Atom feed
From: Dmitry Osipenko <digetx@gmail.com>
To: Chanwoo Choi <cw00.choi@samsung.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	MyungJoo Ham <myungjoo.ham@samsung.com>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: linux-pm@vger.kernel.org, linux-tegra@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 14/24] PM / devfreq: tegra30: Ensure that target freq won't overflow
Date: Tue, 16 Jul 2019 16:59:42 +0300
Message-ID: <14115aa7-ed40-2775-9b0b-a2bf6ca9d47e@gmail.com> (raw)
In-Reply-To: <e6b53ba0-ac98-bda6-b087-553088a43d9f@samsung.com>

16.07.2019 15:30, Chanwoo Choi пишет:
> On 19. 7. 8. 오전 7:32, Dmitry Osipenko wrote:
>> Potentially very high boosting could cause an integer overflow for a
>> highly clocked memory after conversion to MHz.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>> ---
>>  drivers/devfreq/tegra30-devfreq.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
>> index 2f59c78930bd..0de1efdaabf4 100644
>> --- a/drivers/devfreq/tegra30-devfreq.c
>> +++ b/drivers/devfreq/tegra30-devfreq.c
>> @@ -460,6 +460,7 @@ static unsigned long actmon_update_target(struct tegra_devfreq *tegra,
>>  	unsigned long target_freq;
>>  
>>  	target_freq = dev->avg_count / ACTMON_SAMPLING_PERIOD + dev->boost_freq;
>> +	target_freq = min(target_freq, ULONG_MAX / KHZ);
> 
> Did you meet this corner case?

I can't recall that, technically it could happen and I don't feel
comfortable by having potential integer overflows anyway.

> If have to change it, you better to use 'tegra->max_freq' as following:
> 	min(target_freq, tegra->max_freq);

The 'tegra->max_freq' will work here, but 'ULONG_MAX / KHZ' is a
constant value which is also correct and doesn't case any harm.

Probably will be even more expressive to write this as:

	target_freq = dev->avg_freq + dev->boost_freq;
	target_freq = tegra_actmon_account_cpu_freq(tegra, dev, target_freq);

	return min(target_freq, tegra->max_freq);


Thank you very much for the reviews!

  reply index

Thread overview: 94+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-07 22:32 [PATCH v4 00/24] More improvements for Tegra30 devfreq driver Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 01/24] PM / devfreq: tegra30: Change irq type to unsigned int Dmitry Osipenko
2019-07-16 11:35   ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 02/24] PM / devfreq: tegra30: Keep interrupt disabled while governor is stopped Dmitry Osipenko
2019-07-16 11:47   ` Chanwoo Choi
2019-07-16 13:03     ` Dmitry Osipenko
2019-07-17  6:37       ` Chanwoo Choi
2019-07-17 16:44         ` Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 03/24] PM / devfreq: tegra30: Handle possible round-rate error Dmitry Osipenko
2019-07-16 11:50   ` Chanwoo Choi
2019-07-16 13:09     ` Dmitry Osipenko
2019-07-17  6:38       ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 04/24] PM / devfreq: tegra30: Drop write-barrier Dmitry Osipenko
2019-07-16 11:51   ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 05/24] PM / devfreq: tegra30: Set up watermarks properly Dmitry Osipenko
2019-07-18 10:17   ` Chanwoo Choi
2019-07-19  0:00     ` Dmitry Osipenko
2019-07-19  1:31       ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 06/24] PM / devfreq: tegra30: Tune up boosting thresholds Dmitry Osipenko
2019-07-16 11:55   ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 07/24] PM / devfreq: tegra30: Use CPUFreq notifier Dmitry Osipenko
2019-07-16 12:08   ` Chanwoo Choi
2019-07-16 13:18     ` Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 08/24] PM / devfreq: tegra30: Move clk-notifier's registration to governor's start Dmitry Osipenko
2019-07-16 12:11   ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 09/24] PM / devfreq: tegra30: Reset boosting on startup Dmitry Osipenko
2019-07-16 12:13   ` Chanwoo Choi
2019-07-16 13:19     ` Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 10/24] PM / devfreq: tegra30: Don't enable consecutive-down interrupt " Dmitry Osipenko
2019-07-16 12:17   ` Chanwoo Choi
2019-07-16 15:17     ` Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 11/24] PM / devfreq: tegra30: Add debug messages Dmitry Osipenko
2019-07-16 12:23   ` Chanwoo Choi
2019-07-16 13:26     ` Dmitry Osipenko
2019-07-17  6:45       ` Chanwoo Choi
2019-07-17 15:46         ` Dmitry Osipenko
2019-07-18  9:07           ` Chanwoo Choi
2019-07-19  1:13             ` Dmitry Osipenko
2019-07-19  1:22               ` Chanwoo Choi
2019-07-19 17:10                 ` Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 12/24] PM / devfreq: tegra30: Inline all one-line functions Dmitry Osipenko
2019-07-16 12:26   ` Chanwoo Choi
2019-07-16 13:35     ` Dmitry Osipenko
2019-07-18  9:09       ` Chanwoo Choi
2019-07-19  1:22         ` Dmitry Osipenko
2019-07-19  1:24           ` Chanwoo Choi
2019-07-19  1:27             ` Chanwoo Choi
2019-07-19  2:14               ` Dmitry Osipenko
2019-07-19  6:01                 ` Chanwoo Choi
2019-07-19 16:52                   ` Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 13/24] PM / devfreq: tegra30: Constify structs Dmitry Osipenko
2019-07-16 12:26   ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 14/24] PM / devfreq: tegra30: Ensure that target freq won't overflow Dmitry Osipenko
2019-07-16 12:30   ` Chanwoo Choi
2019-07-16 13:59     ` Dmitry Osipenko [this message]
2019-07-07 22:32 ` [PATCH v4 15/24] PM / devfreq: tegra30: Fix integer overflow on CPU's freq max out Dmitry Osipenko
2019-07-16 12:32   ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 16/24] PM / devfreq: tegra30: Use kHz units uniformly in the code Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 17/24] PM / devfreq: tegra30: Use tracepoints for debugging Dmitry Osipenko
2019-07-18  9:47   ` Chanwoo Choi
2019-07-19  0:49     ` Dmitry Osipenko
2019-07-19  1:01       ` Chanwoo Choi
2019-07-19  1:50         ` Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 18/24] PM / devfreq: tegra30: Optimize CPUFreq notifier Dmitry Osipenko
2019-07-18  9:48   ` Chanwoo Choi
2019-07-19  0:42     ` Dmitry Osipenko
2019-07-19  1:09       ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 19/24] PM / devfreq: tegra30: Optimize upper consecutive watermark selection Dmitry Osipenko
2019-07-18  9:51   ` Chanwoo Choi
2019-07-19  0:40     ` Dmitry Osipenko
2019-07-19  1:15       ` Chanwoo Choi
2019-07-19  1:17         ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 20/24] PM / devfreq: tegra30: Optimize upper average " Dmitry Osipenko
2019-07-19  1:36   ` Chanwoo Choi
2019-07-19  1:59     ` Dmitry Osipenko
2019-07-19  2:06       ` Chanwoo Choi
2019-07-19  2:21         ` Dmitry Osipenko
2019-07-19  6:09           ` Chanwoo Choi
2019-07-19  6:11             ` Chanwoo Choi
2019-07-19 17:52               ` Dmitry Osipenko
2019-07-24 11:17                 ` Chanwoo Choi
2019-07-24 11:19                   ` Chanwoo Choi
2019-07-07 22:33 ` [PATCH v4 21/24] PM / devfreq: tegra30: Synchronize average count on target's update Dmitry Osipenko
2019-07-18 10:15   ` Chanwoo Choi
2019-07-19  0:31     ` Dmitry Osipenko
2019-07-19  1:40       ` Chanwoo Choi
2019-07-19 16:46         ` Dmitry Osipenko
2019-07-07 22:33 ` [PATCH v4 22/24] PM / devfreq: tegra30: Include appropriate header Dmitry Osipenko
2019-07-18  9:58   ` Chanwoo Choi
2019-07-19  0:34     ` Dmitry Osipenko
2019-07-07 22:33 ` [PATCH v4 23/24] PM / devfreq: tegra30: Increase sampling period to 16ms Dmitry Osipenko
2019-07-18 10:00   ` Chanwoo Choi
2019-07-07 22:33 ` [PATCH v4 24/24] PM / devfreq: tegra20/30: Add Dmitry as a maintainer Dmitry Osipenko
2019-07-18  9:56   ` Chanwoo Choi

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=14115aa7-ed40-2775-9b0b-a2bf6ca9d47e@gmail.com \
    --to=digetx@gmail.com \
    --cc=cw00.choi@samsung.com \
    --cc=jonathanh@nvidia.com \
    --cc=kyungmin.park@samsung.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=linux-tegra@vger.kernel.org \
    --cc=myungjoo.ham@samsung.com \
    --cc=thierry.reding@gmail.com \
    --cc=tomeu.vizoso@collabora.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-PM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-pm/0 linux-pm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-pm linux-pm/ https://lore.kernel.org/linux-pm \
		linux-pm@vger.kernel.org
	public-inbox-index linux-pm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-pm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git