From: Oleh Kravchenko <oleg@kaa.org.ua>
To: Pavel Machek <pavel@ucw.cz>
Cc: linux-leds@vger.kernel.org
Subject: Re: [PATCH 2/2] leds: ns2: Fix wrong boolean expression
Date: Tue, 3 Sep 2019 22:46:32 +0300 [thread overview]
Message-ID: <4B55F03E-03C9-44BA-A4CB-AADA29FC4271@kaa.org.ua> (raw)
In-Reply-To: <20190903185006.GA10875@amd>
Pavel,
> On Sep 3, 2019, at 9:50 PM, Pavel Machek <pavel@ucw.cz> wrote:
>
> On Tue 2019-09-03 19:00:21, Oleh Kravchenko wrote:
>> Hello Pavel,
>>
>> 03.09.19 17:12, Pavel Machek пише:
>>> On Tue 2019-09-03 15:50:20, Oleh Kravchenko wrote:
>>>> Error was detected by PVS-Studio:
>>>> V792 The '__gpio_cansleep' function located to the right of
>>>> the operator '|' will be called regardless of the value of
>>>> the left operand. Perhaps, it is better to use '||'.
>>> 1st: original code is not wrong
>>
>> '|' is bitwise operation, if it really means *OR* then should be '||' -
>> led_dat->can_sleep is bool.
>
> I see that || would be more natural. But | also works.
>
>>> 2nd: you are introducing a bug
>>
>> No, because if GPIOs *slow* can sleep and GPIO *cmd* can't sleep
>> it will call gpio_set_value_cansleep() for both.
>
> If just one of them can sleep, can_sleep will be 0, and bad things
> will happen, right?
With current code if just one of them can sleep, can_sleep will be not zero (!= 0).
And bad things will happen.
>
>
>>>> @@ -205,7 +205,7 @@ create_ns2_led(struct platform_device *pdev, struct ns2_led_data *led_dat,
>>>> led_dat->cdev.groups = ns2_led_groups;
>>>> led_dat->cmd = template->cmd;
>>>> led_dat->slow = template->slow;
>>>> - led_dat->can_sleep = gpio_cansleep(led_dat->cmd) |
>>>> + led_dat->can_sleep = gpio_cansleep(led_dat->cmd) &&
>>>> gpio_cansleep(led_dat->slow);
>>>> if (led_dat->can_sleep)
>>>> led_dat->cdev.brightness_set_blocking = ns2_led_set_blocking;
>
> Best regards,
> Pavel
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2019-09-03 19:46 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-03 12:50 [PATCH 1/2] leds: mlxreg: Fix possible buffer overflow Oleh Kravchenko
2019-09-03 12:50 ` [PATCH 2/2] leds: ns2: Fix wrong boolean expression Oleh Kravchenko
2019-09-03 14:12 ` Pavel Machek
2019-09-03 16:00 ` Oleh Kravchenko
2019-09-03 18:50 ` Pavel Machek
2019-09-03 19:46 ` Oleh Kravchenko [this message]
2019-09-03 21:02 ` Oleh Kravchenko
2019-09-03 14:12 ` [PATCH 1/2] leds: mlxreg: Fix possible buffer overflow Pavel Machek
2019-09-03 18:11 ` Oleh Kravchenko
2019-09-07 19:36 ` Pavel Machek
2019-09-08 8:57 ` Oleh Kravchenko
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