Re: [Linaro-acpi] [RFC] ACPI: Add new function to get table entries

On 20.03.2014 11:05, Tomasz Nowicki wrote:

On 20.03.2014 00:09, Ashwin Chaugule wrote:

...

The acpi_table_parse() function has a callback that passes a pointer to a table_header. Add a new function which takes this pointer and parses its entries. This eliminates the need to re-traverse all the tables for each call. e.g. as in acpi_table_parse_madt() which is normally called after acpi_table_parse().

Signed-off-by: Ashwin Chaugule ashwin.chaugule@linaro.org

drivers/acpi/tables.c | 69 +++++++++++++++++++++++++++++++++++---------------- include/linux/acpi.h | 4 +++ 2 files changed, 51 insertions(+), 22 deletions(-)

diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c index 5837f85..b7bd6a3 100644 --- a/drivers/acpi/tables.c +++ b/drivers/acpi/tables.c @@ -199,19 +199,15 @@ void acpi_table_print_madt_entry(struct acpi_subtable_header *header) } }

• int __init

-acpi_table_parse_entries(char *id,

•             unsigned long table_size,
  

•             int entry_id,
  

•             acpi_tbl_entry_handler handler,
  

•             unsigned int max_entries)
  

+acpi_parse_entries(unsigned long table_size,

•    acpi_tbl_entry_handler handler,
  

•    struct acpi_table_header *table_header,
  

•    int entry_id, unsigned int max_entries)
  

  {

• struct acpi_table_header *table_header = NULL; struct acpi_subtable_header *entry; unsigned int count = 0; unsigned long table_end;

• acpi_size tbl_size;

  if (acpi_disabled) return -ENODEV;

@@ -219,16 +215,14 @@ acpi_table_parse_entries(char *id, if (!handler) return -EINVAL;

• if (strncmp(id, ACPI_SIG_MADT, 4) == 0)

•    acpi_get_table_with_size(id, acpi_apic_instance,
  

&table_header, &tbl_size);

• else

•    acpi_get_table_with_size(id, 0, &table_header, &tbl_size);
  

• if (!table_header) {
  

•    printk(KERN_WARNING PREFIX "%4.4s not present\n", id);
  

•    pr_warn(PREFIX "Table header not present\n");
      return -ENODEV;
  }
  
  

• if (!table_size)

•    table_size = table_header->length;
  

If table_size == 0, that would causes 'entry' and 'table_end' are equal and no entries at all. For that case I would suggest to print error and return.

Tomasz

...

  table_end = (unsigned long)table_header + table_header->length;

  /* Parse all entries looking for a match. */

@@ -240,15 +234,18 @@ acpi_table_parse_entries(char *id, table_end) { if (entry->type == entry_id && (!max_entries || count++ < max_entries))

•        if (handler(entry, table_end))
  

•        if (handler(entry, table_end)) {
  

•            count = -EINVAL;
              goto err;
  

•        }
  
      /*
       * If entry->length is 0, break from this loop to avoid
       * infinite loop.
       */
      if (entry->length == 0) {
  

•        pr_err(PREFIX "[%4.4s:0x%02x] Invalid zero length\n", id,
  

entry_id);

•        pr_err(PREFIX "[0x%02x] Invalid zero length\n", entry_id);
  

•        count = -EINVAL;
          goto err;
      }
  
  

@@ -256,15 +253,43 @@ acpi_table_parse_entries(char *id, ((unsigned long)entry + entry->length); } if (max_entries && count > max_entries) {

•    printk(KERN_WARNING PREFIX "[%4.4s:0x%02x] ignored %i entries
  

of "

•           "%i found\n", id, entry_id, count - max_entries, count);
  

•    printk(KERN_WARNING PREFIX "[0x%02x] ignored %i entries of "
  

•           "%i found\n", entry_id, count - max_entries, count);
  }
  
  

• early_acpi_os_unmap_memory((char *)table_header, tbl_size);
• return count; err:
• early_acpi_os_unmap_memory((char *)table_header, tbl_size);
• return -EINVAL;

• early_acpi_os_unmap_memory((char *)table_header,

(acpi_size)table_size);

• return count;

Changelog is saying that acpi_parse_entries() takes already mapped table and parses entries. IMO, caller should takes care about unmapping table. It can be still parsed using different ID later on.

Tomasz

...

+}

+int __init +acpi_table_parse_entries(char *id,

•             unsigned long table_size,
  

•             int entry_id,
  

•             acpi_tbl_entry_handler handler,
  

•             unsigned int max_entries)
  

+{

• struct acpi_table_header *table_header = NULL;
• acpi_size tbl_size;
• if (acpi_disabled)

•    return -ENODEV;
  

• if (!handler)

•    return -EINVAL;
  

• if (strncmp(id, ACPI_SIG_MADT, 4) == 0)

•    acpi_get_table_with_size(id, acpi_apic_instance,
  

&table_header, &tbl_size);

• else

•    acpi_get_table_with_size(id, 0, &table_header, &tbl_size);
  

• if (!table_header) {

•    pr_warn("%4.4s not present\n", id);
  

•    return -ENODEV;
  

• }
• return acpi_parse_entries(table_header->length, handler,

table_header,

•        entry_id, max_entries);
  

Also, first argument of acpi_parse_entries() expect subtable start point offset, but now it points to the end of table.

Tomasz

...

}

int __init diff --git a/include/linux/acpi.h b/include/linux/acpi.h index 1151a1d..da959fd 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -118,6 +118,10 @@ int acpi_numa_init (void);

int acpi_table_init (void); int acpi_table_parse(char *id, acpi_tbl_table_handler handler); +int __init acpi_parse_entries(unsigned long table_size,

•    acpi_tbl_entry_handler handler,
  

•    struct acpi_table_header *table_header,
  

•    int entry_id, unsigned int max_entries);
  

  int __init acpi_table_parse_entries(char *id, unsigned long table_size, int entry_id, acpi_tbl_entry_handler handler,