On Thursday, April 27, 2017 04:22:50 PM Lv Zheng wrote:
> This patch adds balanced acpi_get_table()/acpi_put_table() support for
> sysfs table dumping code so that no need to call
> acpi_get_validated_table().
>
> Since ACPICA does not use all of the tables, this can help to reduce some
> usless memory mappings by utilizing the new table handling APIs.
>
> The original sysfs dumpable ACPI table implementation forces tables to be
> mapped after a read operation and never unmaps them again whatever there
> are no users in the kernel interested in these tables. With new balanced
> table handling APIs, tables are unmapped after the read operation.
>
> Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx>
> ---
> drivers/acpi/sysfs.c | 51 ++++++++++++++++++++++++++++++++++++---------------
> 1 file changed, 36 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/acpi/sysfs.c b/drivers/acpi/sysfs.c
> index 1b5ee1e..c3bb6ce 100644
> --- a/drivers/acpi/sysfs.c
> +++ b/drivers/acpi/sysfs.c
> @@ -333,21 +333,34 @@ static ssize_t acpi_table_show(struct file *filp, struct kobject *kobj,
> container_of(bin_attr, struct acpi_table_attr, attr);
> struct acpi_table_header *table_header = NULL;
> acpi_status status;
> + ssize_t len;
>
> status = acpi_get_table(table_attr->name, table_attr->instance,
> &table_header);
> if (ACPI_FAILURE(status))
> return -ENODEV;
> + len = memory_read_from_buffer(buf, count, &offset,
> + table_header, table_header->length);
> + acpi_put_table(table_header);
> + return len;
> +}
The above seems to be taken verbatim from the Dan's patch.
If that's the case, please do the below as a separate patch on top of the Dan's
one.
> +
> +static bool acpi_table_has_multiple_instances(char *signature)
> +{
> + acpi_status status;
> + struct acpi_table_header *header;
>
> - return memory_read_from_buffer(buf, count, &offset,
> - table_header, table_header->length);
> + status = acpi_get_table(signature, 2, &header);
> + if (ACPI_FAILURE(status))
> + return false;
> + acpi_put_table(header);
> + return true;
> }
>
> static int acpi_table_attr_init(struct kobject *tables_obj,
> struct acpi_table_attr *table_attr,
> struct acpi_table_header *table_header)
> {
> - struct acpi_table_header *header = NULL;
> struct acpi_table_attr *attr = NULL;
> char instance_str[ACPI_INST_SIZE];
>
> @@ -368,9 +381,9 @@ static int acpi_table_attr_init(struct kobject *tables_obj,
>
> ACPI_MOVE_NAME(table_attr->filename, table_header->signature);
> table_attr->filename[ACPI_NAME_SIZE] = '\0';
> - if (table_attr->instance > 1 || (table_attr->instance == 1 &&
> - !acpi_get_table
> - (table_header->signature, 2, &header))) {
> + if (table_attr->instance > 1 ||
> + (table_attr->instance == 1 &&
> + acpi_table_has_multiple_instances(table_header->signature))) {
> snprintf(instance_str, sizeof(instance_str), "%u",
> table_attr->instance);
> strcat(table_attr->filename, instance_str);
> @@ -419,11 +432,11 @@ acpi_status acpi_sysfs_table_handler(u32 event, void *table, void *context)
>
> static int acpi_tables_sysfs_init(void)
> {
> - struct acpi_table_attr *table_attr;
> + struct acpi_table_attr *table_attr = NULL;
> struct acpi_table_header *table_header = NULL;
> int table_index;
> acpi_status status;
> - int ret;
> + int ret = 0;
>
> tables_kobj = kobject_create_and_add("tables", acpi_kobj);
> if (!tables_kobj)
> @@ -435,24 +448,32 @@ static int acpi_tables_sysfs_init(void)
>
> for (table_index = 0;; table_index++) {
> status = acpi_get_table_by_index(table_index, &table_header);
> -
> if (status == AE_BAD_PARAMETER)
> break;
> -
> if (ACPI_FAILURE(status))
> - continue;
> + goto next_table;
>
> table_attr = kzalloc(sizeof(*table_attr), GFP_KERNEL);
> - if (!table_attr)
> - return -ENOMEM;
> + if (!table_attr) {
> + ret = -ENOMEM;
> + goto next_table;
> + }
>
> ret = acpi_table_attr_init(tables_kobj,
> table_attr, table_header);
> + if (ret)
> + goto next_table;
> + list_add_tail(&table_attr->node, &acpi_table_attr_list);
> +
> +next_table:
> + acpi_put_table(table_header);
> if (ret) {
> - kfree(table_attr);
> + if (table_attr) {
> + kfree(table_attr);
> + table_attr = NULL;
> + }
> return ret;
> }
> - list_add_tail(&table_attr->node, &acpi_table_attr_list);
> }
>
> kobject_uevent(tables_kobj, KOBJ_ADD);
>
Thanks,
Rafael
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