linux-kernel - Re: [PATCH V4 1/2] ACPI / EC: Fix broken 64bit big-endian users of 'global

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Message-ID: <1460975.zriLPuubXp@vostro.rjw.lan>
Date:	Fri, 25 Sep 2015 22:18:13 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Viresh Kumar <viresh.kumar@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linaro-kernel@...ts.linaro.org,
	QCA ath9k Development <ath9k-devel@....qualcomm.com>,
	Intel Linux Wireless <ilw@...ux.intel.com>,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-acpi@...r.kernel.org,
	linux-bluetooth@...r.kernel.org, iommu@...ts.linux-foundation.org,
	netdev@...r.kernel.org, linux-wireless@...r.kernel.org,
	linux-scsi@...r.kernel.org, linux-usb@...r.kernel.org,
	linux-edac@...r.kernel.org, linux-mm@...ck.org,
	alsa-devel@...a-project.org
Subject: Re: [PATCH V4 1/2] ACPI / EC: Fix broken 64bit big-endian users of 'global_lock'

On Friday, September 25, 2015 09:41:37 AM Viresh Kumar wrote:
> global_lock is defined as an unsigned long and accessing only its lower
> 32 bits from sysfs is incorrect, as we need to consider other 32 bits
> for big endian 64 bit systems. There are no such platforms yet, but the
> code needs to be robust for such a case.
> 
> Fix that by passing a local variable to debugfs_create_bool() and
> assigning its value to global_lock later.
> 
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Greg, please take this one if the [2/2] looks good to you.

> ---
> V3->V4:
> - Create a local variable instead of changing type of global_lock
>   (Rafael)
> - Drop the stable tag
> - BCC'd a lot of people (rather than cc'ing them) to make sure
>   - the series reaches them
>   - mailing lists do not block the patchset due to long cc list
>   - and we don't spam the BCC'd people for every reply
> ---
>  drivers/acpi/ec_sys.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/acpi/ec_sys.c b/drivers/acpi/ec_sys.c
> index b4c216bab22b..b44b91331a56 100644
> --- a/drivers/acpi/ec_sys.c
> +++ b/drivers/acpi/ec_sys.c
> @@ -110,6 +110,7 @@ static int acpi_ec_add_debugfs(struct acpi_ec *ec, unsigned int ec_device_count)
>  	struct dentry *dev_dir;
>  	char name[64];
>  	umode_t mode = 0400;
> +	u32 val;
>  
>  	if (ec_device_count == 0) {
>  		acpi_ec_debugfs_dir = debugfs_create_dir("ec", NULL);
> @@ -127,10 +128,11 @@ static int acpi_ec_add_debugfs(struct acpi_ec *ec, unsigned int ec_device_count)
>  
>  	if (!debugfs_create_x32("gpe", 0444, dev_dir, (u32 *)&first_ec->gpe))
>  		goto error;
> -	if (!debugfs_create_bool("use_global_lock", 0444, dev_dir,
> -				 (u32 *)&first_ec->global_lock))
> +	if (!debugfs_create_bool("use_global_lock", 0444, dev_dir, &val))
>  		goto error;
>  
> +	first_ec->global_lock = val;
> +
>  	if (write_support)
>  		mode = 0600;
>  	if (!debugfs_create_file("io", mode, dev_dir, ec, &acpi_ec_io_ops))
> 

Thanks,
Rafael

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