linux-kernel - Re: [PATCH 2/3] leds: lp5521/5523: Remove duplicate mutex

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Message-ID: <CAK5ve-JEsBy6gd+oVwpnzkQe7eTmW6qkK-Rb4cM-JkKHPdiC9g@mail.gmail.com>
Date:	Mon, 2 Dec 2013 11:40:10 -0800
From:	Bryan Wu <cooloney@...il.com>
To:	Milo Kim <milo.kim@...com>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	Linux LED Subsystem <linux-leds@...r.kernel.org>,
	Pali Rohár <pali.rohar@...il.com>
Subject: Re: [PATCH 2/3] leds: lp5521/5523: Remove duplicate mutex

On Wed, Nov 20, 2013 at 10:14 PM, Milo Kim <milo.kim@...com> wrote:
> It can be a problem when a pattern is loaded via the firmware interface.
> LP55xx common driver has already locked the mutex in 'lp55xx_firmware_loaded()'.
> So it should be deleted.
>

Looks like lp5521_update_program_memory() will be called by
store_engine_load() without holding a lock after this change, is this
correct? I think you need also update store_engine_load() to hold the
lock when calling lp5521_update_program_memory().

Thanks,
-Bryan

> Cc: Pali Rohár <pali.rohar@...il.com>
> Signed-off-by: Milo Kim <milo.kim@...com>
> ---
>  drivers/leds/leds-lp5521.c |    4 ----
>  drivers/leds/leds-lp5523.c |    4 ----
>  2 files changed, 8 deletions(-)
>
> diff --git a/drivers/leds/leds-lp5521.c b/drivers/leds/leds-lp5521.c
> index 26f89ac..4c45ed9 100644
> --- a/drivers/leds/leds-lp5521.c
> +++ b/drivers/leds/leds-lp5521.c
> @@ -258,8 +258,6 @@ static int lp5521_update_program_memory(struct lp55xx_chip *chip,
>         if (i % 2)
>                 goto err;
>
> -       mutex_lock(&chip->lock);
> -
>         for (i = 0; i < LP5521_PROGRAM_LENGTH; i++) {
>                 ret = lp55xx_write(chip, addr[idx] + i, pattern[i]);
>                 if (ret) {
> @@ -268,8 +266,6 @@ static int lp5521_update_program_memory(struct lp55xx_chip *chip,
>                 }
>         }
>
> -       mutex_unlock(&chip->lock);
> -
>         return size;
>
>  err:
> diff --git a/drivers/leds/leds-lp5523.c b/drivers/leds/leds-lp5523.c
> index 2ce1723..7a3b369 100644
> --- a/drivers/leds/leds-lp5523.c
> +++ b/drivers/leds/leds-lp5523.c
> @@ -351,8 +351,6 @@ static int lp5523_update_program_memory(struct lp55xx_chip *chip,
>         if (i % 2)
>                 goto err;
>
> -       mutex_lock(&chip->lock);
> -
>         for (i = 0; i < LP5523_PROGRAM_LENGTH; i++) {
>                 ret = lp55xx_write(chip, LP5523_REG_PROG_MEM + i, pattern[i]);
>                 if (ret) {
> @@ -361,8 +359,6 @@ static int lp5523_update_program_memory(struct lp55xx_chip *chip,
>                 }
>         }
>
> -       mutex_unlock(&chip->lock);
> -
>         return size;
>
>  err:
> --
> 1.7.9.5
>
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