From: Xiaofei Tan
> Sent: 27 March 2021 07:46
>
> Replace __attribute__((packed)) by __packed following the
> advice of checkpatch.pl.
>
> Signed-off-by: Xiaofei Tan <tanxiaofei@xxxxxxxxxx>
> ---
> drivers/acpi/acpi_fpdt.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/acpi/acpi_fpdt.c b/drivers/acpi/acpi_fpdt.c
> index a89a806..690a88a 100644
> --- a/drivers/acpi/acpi_fpdt.c
> +++ b/drivers/acpi/acpi_fpdt.c
> @@ -53,7 +53,7 @@ struct resume_performance_record {
> u32 resume_count;
> u64 resume_prev;
> u64 resume_avg;
> -} __attribute__((packed));
> +} __packed;
>
> struct boot_performance_record {
> struct fpdt_record_header header;
> @@ -63,13 +63,13 @@ struct boot_performance_record {
> u64 bootloader_launch;
> u64 exitbootservice_start;
> u64 exitbootservice_end;
> -} __attribute__((packed));
> +} __packed;
>
> struct suspend_performance_record {
> struct fpdt_record_header header;
> u64 suspend_start;
> u64 suspend_end;
> -} __attribute__((packed));
> +} __packed;
My standard question about 'packed' is whether it is actually needed.
It should only be used if the structures might be misaligned in memory.
If the only problem is that a 64bit item needs to be 32bit aligned
then a suitable type should be used for those specific fields.
Those all look very dubious - the standard header isn't packed
so everything must eb assumed to be at least 32bit aligned.
There are also other sub-structures that contain 64bit values.
These don't contain padding - but that requires 64bit alignement.
The only problematic structure is the last one - which would have
a 32bit pad after the header.
Is this even right given than there are explicit alignment pads
in some of the other structures.
If 64bit alignment isn't guaranteed then a '64bit aligned to 32bit'
type should be used for the u64 fields.
David
-
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