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

Jiri Slaby
2015-09-27T05:31:53Z

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Dne 25. 9. 2015 18:42 napsal uživatel "Viresh Kumar" <
viresh.kumar@linaro.org>:
>
> 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.

But this has to crash whenever the file is read as val's storage is gone at
that moment already, right?

> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
> ---
> 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))
> --
> 2.4.0
>

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