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SubjectRe: [PATCH v3 1/5] ACPI / blacklist: add acpi_match_platform_list()
On Fri, Aug 18, 2017 at 01:46:40PM -0600, Toshi Kani wrote:
> ACPI OEM ID / OEM Table ID / Revision can be used to identify
> a platform based on ACPI firmware info. acpi_blacklisted(),
> intel_pstate_platform_pwr_mgmt_exists(), and some other funcs,
> have been using similar check to detect a list of platforms
> that require special handlings.
>
> Move the platform check in acpi_blacklisted() to a new common
> utility function, acpi_match_platform_list(), so that other
> drivers do not have to implement their own version.
>
> There is no change in functionality.
>
> Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> Cc: Borislav Petkov <bp@alien8.de>
> ---
> drivers/acpi/blacklist.c | 83 ++++++++--------------------------------------
> drivers/acpi/utils.c | 40 ++++++++++++++++++++++
> include/linux/acpi.h | 19 +++++++++++
> 3 files changed, 73 insertions(+), 69 deletions(-)

...

> diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c
> index b9d956c..998aaf5 100644
> --- a/drivers/acpi/utils.c
> +++ b/drivers/acpi/utils.c
> @@ -816,3 +816,43 @@ static int __init acpi_backlight(char *str)
> return 1;
> }
> __setup("acpi_backlight=", acpi_backlight);
> +
> +/**
> + * acpi_match_platform_list - Check if the system matches with a given list
> + * @plat: pointer to acpi_platform_list table terminated by a NULL entry
> + *
> + * Return the matched index if the system is found in the platform list.
> + * Otherwise, return a negative error code.
> + */
> +int acpi_match_platform_list(const struct acpi_platform_list *plat)
> +{
> + struct acpi_table_header hdr;
> + int idx = 0;
> +
> + if (acpi_disabled)
> + return -ENODEV;

Btw, Rafael, should we do something like this:

diff --git a/drivers/acpi/acpica/tbxface.c b/drivers/acpi/acpica/tbxface.c
index 010b1c43df92..881b0d5b2838 100644
--- a/drivers/acpi/acpica/tbxface.c
+++ b/drivers/acpi/acpica/tbxface.c
@@ -226,6 +226,9 @@ acpi_get_table_header(char *signature,
u32 j;
struct acpi_table_header *header;

+ if (acpi_disabled)
+ return (AE_ERROR);
+
/* Parameter validation */

if (!signature || !out_table_header) {
---
in order to avoid that sprinkling of if (acpi_disabled) everywhere?
> +
> + for (; plat->oem_id[0]; plat++, idx++) {
> + if (ACPI_FAILURE(acpi_get_table_header(plat->table, 0, &hdr)))
> + continue;
> +
> + if (strncmp(plat->oem_id, hdr.oem_id, ACPI_OEM_ID_SIZE))
> + continue;
> +
> + if (strncmp(plat->oem_table_id, hdr.oem_table_id,
> + ACPI_OEM_TABLE_ID_SIZE))

Let that stick out.

> + continue;
> +
> + if ((plat->pred == all_versions) ||
> + (plat->pred == less_than_or_equal
> + && hdr.oem_revision <= plat->oem_revision) ||
> + (plat->pred == greater_than_or_equal
> + && hdr.oem_revision >= plat->oem_revision) ||
> + (plat->pred == equal
> + && hdr.oem_revision == plat->oem_revision))
> + return idx;

Make that more readable:

if ((plat->pred == all_versions) ||
(plat->pred == less_than_or_equal && hdr.oem_revision <= plat->oem_revision) ||
(plat->pred == greater_than_or_equal && hdr.oem_revision >= plat->oem_revision) ||
(plat->pred == equal && hdr.oem_revision == plat->oem_revision))
return idx;

> + }
> +
> + return -ENODEV;
> +}
> +EXPORT_SYMBOL(acpi_match_platform_list);
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 27b4b66..a9b6dc2 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -556,6 +556,25 @@ extern acpi_status acpi_pci_osc_control_set(acpi_handle handle,
> #define ACPI_OST_SC_DRIVER_LOAD_FAILURE 0x81
> #define ACPI_OST_SC_INSERT_NOT_SUPPORTED 0x82
>
> +enum acpi_predicate {
> + all_versions,
> + less_than_or_equal,
> + equal,
> + greater_than_or_equal,
> +};
> +
> +/* Table must be terminted by a NULL entry */
> +struct acpi_platform_list {
> + char oem_id[ACPI_OEM_ID_SIZE];

+ 1

> + char oem_table_id[ACPI_OEM_TABLE_ID_SIZE];

+ 1
> + u32 oem_revision;
> + char *table;
> + enum acpi_predicate pred;
> + char *reason;
> + u32 data;

Ok, turning that into data from is_critical_error is a step in the right
direction. Let's make it even better:

u32 flags;

and do

#define ACPI_PLAT_IS_CRITICAL_ERROR BIT(0)

so that future elements add new bits instead of wasting a whole u32 as a
boolean.

--
Regards/Gruss,
Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

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