linux-kernel - Re: [PATCH] i2c: nvidia-gpu: Handle timeout correctly in gpu_i2c_check

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Message-ID: <20200324110930.GH1134@ninjato>
Date:   Tue, 24 Mar 2020 12:09:30 +0100
From:   Wolfram Sang <wsa@...-dreams.de>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc:     ajayg@...dia.com,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "open list:I2C CONTROLLER DRIVER FOR NVIDIA GPU" 
        <linux-i2c@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] i2c: nvidia-gpu: Handle timeout correctly in
 gpu_i2c_check_status()


>  	} while (time_is_after_jiffies(target));
>  
> -	if (time_is_before_jiffies(target)) {
> +	if (time_is_before_eq_jiffies(target)) {

While unlikely, there is a tiny race between the time_is_* calls,
jiffies could update inbetween them.

So, for the sake of good programming practice, I'd recommend to set a
flag in the do_while-loop and the have the logic above solely based on
the flag.


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