linux-kernel - Re: AW: [PATCH 2/2] tty: serial: samsung_tty: Fix a memory leak in s3c24xx_serial

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Message-ID: <f3607725-b08c-8d96-02f8-f8f89af8e8b1@linaro.org>
Date:   Fri, 9 Jun 2023 13:56:19 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Walter Harms <wharms@....de>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Thomas Abraham <thomas.abraham@...aro.org>,
        Kukjin Kim <kgene.kim@...sung.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-samsung-soc@...r.kernel.org" 
        <linux-samsung-soc@...r.kernel.org>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>
Subject: Re: AW: [PATCH 2/2] tty: serial: samsung_tty: Fix a memory leak in
 s3c24xx_serial_getclk() when iterating clk

On 09/06/2023 10:57, Walter Harms wrote:
> 
> while we are here ....
> 
> perhaps INT_MAX from kernel.h ?
> 
> int   deviation = (1 << 30) - 1;
> 
> the part before looks a bit strange
> 
> if (ourport->info->has_divslot) {
>                         unsigned long div = rate / req_baud;
> 
>                         /* The UDIVSLOT register on the newer UARTs allows us to
>                          * get a divisor adjustment of 1/16th on the baud clock.
>                          *
>                          * We don't keep the UDIVSLOT value (the 16ths we
>                          * calculated by not multiplying the baud by 16) as it
>                          * is easy enough to recalculate.
>                          */
> 
>                         quot = div / 16;
>                         baud = rate / div;
> because
>    baud=rate/rate/req_baud = req_baud
> can this be simplyfied ? (or is the numeric required  ?)
> 
> 
> Homebrew abs()  kernel.h has a abs() can we use it here ?
> 
>             if (calc_deviation < 0)
>                         calc_deviation = -calc_deviation;
> 
> to the patch:
> 
> +                       /*
> +                        * If we find a better clk, release the previous one, if
> +                        * any.
> +                        */
> +                       if (!IS_ERR(*best_clk))
> +                               clk_put(*best_clk);
> 
> the intentions are good. *best_clk is user supplied (and should be NULL)
> filled & released in the next round but IMHO must be valid (is clk).
> so no need to check. (ntl clk_put seems to handle NULL and ERR )
>    if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
>                 return;

Don't top-post.

Anyway, I don't understand what you want to say here.

Best regards,
Krzysztof