From: Pavel Machek <pavel@ucw.cz>
To: Oleh Kravchenko <oleg@kaa.org.ua>
Cc: linux-leds@vger.kernel.org
Subject: Re: [PATCH 2/2] leds: ns2: Fix wrong boolean expression
Date: Tue, 3 Sep 2019 20:50:06 +0200 [thread overview]
Message-ID: <20190903185006.GA10875@amd> (raw)
In-Reply-To: <e7384bf0-dc94-f678-5aaa-e936b27f1650@kaa.org.ua>
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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?
> >> @@ -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
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next prev parent reply other threads:[~2019-09-03 18:50 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 [this message]
2019-09-03 19:46 ` Oleh Kravchenko
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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