linux-kernel - Re: [PATCH 2/5] ACPI / debugger: Fix regressions that AML debugger stops working

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Date:	Wed, 6 Jul 2016 01:41:50 +0200
From:	"Rafael J. Wysocki" <rafael@...nel.org>
To:	Lv Zheng <lv.zheng@...el.com>
Cc:	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <len.brown@...el.com>, Lv Zheng <zetalog@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH 2/5] ACPI / debugger: Fix regressions that AML debugger
 stops working

On Tue, Jul 5, 2016 at 1:18 PM, Lv Zheng <lv.zheng@...el.com> wrote:
> The FIFO unlocking mechanism in acpi_dbg has been messed up by the
> following commit:
>   Commit: 287980e49ffc0f6d911601e7e352a812ed27768e
>   Subject: remove lots of IS_ERR_VALUE abuses
> It converts !IS_ERR_VALUE(ret) into !ret. This patch fixes the
> regression.
>
> Fixes: 287980e49ffc ("remove lots of IS_ERR_VALUE abuses")
> Signed-off-by: Lv Zheng <lv.zheng@...el.com>
> Cc: Arnd Bergmann <arnd@...db.de>

OK, but ->

> ---
>  drivers/acpi/acpi_dbg.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/acpi/acpi_dbg.c b/drivers/acpi/acpi_dbg.c
> index 1f41284..ebc8d18 100644
> --- a/drivers/acpi/acpi_dbg.c
> +++ b/drivers/acpi/acpi_dbg.c
> @@ -602,7 +602,8 @@ static int acpi_aml_read_user(char __user *buf, int len)
>         crc->tail = (crc->tail + n) & (ACPI_AML_BUF_SIZE - 1);
>         ret = n;
>  out:
> -       acpi_aml_unlock_fifo(ACPI_AML_OUT_USER, !ret);
> +       acpi_aml_unlock_fifo(ACPI_AML_OUT_USER,
> +                            ret < 0 ? false : true);

-> The ternary operation is not necessary here, because the result of
(ret < 0) is already boolean.  So this can be written as

acpi_aml_unlock_fifo(ACPI_AML_OUT_USER, ret >= 0);

and analogously below.

I've made that change, please check the result in bleeding-edge.

Thanks,
Rafael