Re: [PATCH v5 02/18] ACPI / table: Add new function to get table entries

[Rafael J. Wysocki]

On Tuesday, November 25, 2014 11:38:05 AM Hanjun Guo wrote:
> On 2014/11/24 22:51, Rafael J. Wysocki wrote:
> > On Monday, November 24, 2014 07:03:54 PM Hanjun Guo wrote:
> >> On 2014-11-24 9:27, Rafael J. Wysocki wrote:
> >>> On Friday, October 17, 2014 09:36:58 PM Hanjun Guo wrote:
> >>>> From: Ashwin Chaugule <ashwin.chaugule@xxxxxxxxxx>
> >>>>
> >>>> 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().
> >>>>
> >>>> Acked-by: Grant Likely <grant.likely@xxxxxxxxxx>
> >>>> Signed-off-by: Ashwin Chaugule <ashwin.chaugule@xxxxxxxxxx>
> >>>> Signed-off-by: Tomasz Nowicki <tomasz.nowicki@xxxxxxxxxx>
> >>>> Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
> >>>> ---
> >>>>  drivers/acpi/tables.c |   67 ++++++++++++++++++++++++++++++++++---------------
> >>>>  include/linux/acpi.h  |    4 +++
> >>>>  2 files changed, 51 insertions(+), 20 deletions(-)
> >>>>
> >>>> diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
> >>>> index 6d5a6cd..21ae521 100644
> >>>> --- a/drivers/acpi/tables.c
> >>>> +++ b/drivers/acpi/tables.c
> >>>> @@ -192,17 +192,14 @@ 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;
> >>>> +	int count = 0;
> >>>>  	unsigned long table_end;
> >>>> -	acpi_size tbl_size;
> >>>>  
> >>>>  	if (acpi_disabled)
> >>>>  		return -ENODEV;
> >>>> @@ -210,13 +207,11 @@ 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_size)
> >>>> +		return -EINVAL;
> >>>>  
> >>>>  	if (!table_header) {
> >>>> -		pr_warn("%4.4s not present\n", id);
> >>>> +		pr_warn("Table header not present\n");
> >>> The message doesn't make sense any more if the table signature is not printed.
> 
> For this message, since no table id is passed, and this message is printed in
> acpi_table_parse_entries() before this function is called, I think we can check
> the table_header before call this function and remove the printed message here.

table_header needs to be checked against NULL in the caller and the message
printed from there to my eyes.

> >>>
> >>>>  		return -ENODEV;
> >>>>  	}
> >>>>  
> >>>> @@ -232,30 +227,62 @@ acpi_table_parse_entries(char *id,
> >>>>  		if (entry->type == entry_id
> >>>>  		    && (!max_entries || count++ < max_entries))
> >>>>  			if (handler(entry, table_end))
> >>>> -				goto err;
> >>>> +				return -EINVAL;
> >>>>  
> >>>>  		/*
> >>>>  		 * If entry->length is 0, break from this loop to avoid
> >>>>  		 * infinite loop.
> >>>>  		 */
> >>>>  		if (entry->length == 0) {
> >>>> -			pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, entry_id);
> >>>> -			goto err;
> >>>> +			pr_err("[0x%02x] Invalid zero length\n", entry_id);
> 
> For this one, since the table_header is valid now, we can keep it with:

Fine by me.

> - pr_err("[%4.4s:0x%02x] Invalid zero length\n", id, entry_id);
> + pr_err("[%4.4s:0x%02x] Invalid zero length\n", table_header->signature, entry_id);
> 
> >>> Same here.
> >> How about remove the message and return directly?
> > We could do that, but for what reason?  Is the message not useful?
> 
> I agree with you, the message is useful I think, how about the comments above?

Please see above.

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/