Re: [PATCH v2 1/3] libata: fix reading concurrent positioning ranges log

[Hannes Reinecke <hare@suse.de>]

On 6/3/22 09:07, Damien Le Moal wrote:
> On 6/3/22 15:17, Hannes Reinecke wrote:
>> On 6/3/22 00:51, Tyler Erickson wrote:
>>> The concurrent positioning ranges log is not a fixed size and may depend
>>> on how many ranges are supported by the device. This patch uses the size
>>> reported in the GPL directory to determine the number of pages supported
>>> by the device before attempting to read this log page.
>>>
>>> This resolves this error from the dmesg output:
>>>       ata6.00: Read log 0x47 page 0x00 failed, Emask 0x1
>>>
>>> Cc: stable@vger.kernel.org
>>> Fixes: fe22e1c2f705 ("libata: support concurrent positioning ranges log")
>>> Signed-off-by: Tyler Erickson <tyler.erickson@seagate.com>
>>> Reviewed-by: Muhammad Ahmad <muhammad.ahmad@seagate.com>
>>> Tested-by: Michael English <michael.english@seagate.com>
>>> ---
>>>    drivers/ata/libata-core.c | 21 +++++++++++++--------
>>>    1 file changed, 13 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
>>> index 40e816419f48..3ea10f72cb70 100644
>>> --- a/drivers/ata/libata-core.c
>>> +++ b/drivers/ata/libata-core.c
>>> @@ -2010,16 +2010,16 @@ unsigned int ata_read_log_page(struct ata_device *dev, u8 log,
>>>    	return err_mask;
>>>    }
>>>    
>>> -static bool ata_log_supported(struct ata_device *dev, u8 log)
>>> +static int ata_log_supported(struct ata_device *dev, u8 log)
>>>    {
>>>    	struct ata_port *ap = dev->link->ap;
>>>    
>>>    	if (dev->horkage & ATA_HORKAGE_NO_LOG_DIR)
>>> -		return false;
>>> +		return 0;
>>>    
>>>    	if (ata_read_log_page(dev, ATA_LOG_DIRECTORY, 0, ap->sector_buf, 1))
>>> -		return false;
>>> -	return get_unaligned_le16(&ap->sector_buf[log * 2]) ? true : false;
>>> +		return 0;
>>> +	return get_unaligned_le16(&ap->sector_buf[log * 2]);
>>>    }
>>>    
>> Maybe we should change to name of the function here;
>> 'ata_log_supported()' suggests a bool return.
>>
>> ata_check_log_page() ?
>>
>>>    static bool ata_identify_page_supported(struct ata_device *dev, u8 page)
>>> @@ -2455,15 +2455,20 @@ static void ata_dev_config_cpr(struct ata_device *dev)
>>>    	struct ata_cpr_log *cpr_log = NULL;
>>>    	u8 *desc, *buf = NULL;
>>>    
>>> -	if (ata_id_major_version(dev->id) < 11 ||
>>> -	    !ata_log_supported(dev, ATA_LOG_CONCURRENT_POSITIONING_RANGES))
>>> +	if (ata_id_major_version(dev->id) < 11)
>>> +		goto out;
>>> +
>>> +	buf_len = ata_log_supported(dev, ATA_LOG_CONCURRENT_POSITIONING_RANGES);
>>> +	if (buf_len == 0)
>>>    		goto out;
>>>    
>>>    	/*
>>>    	 * Read the concurrent positioning ranges log (0x47). We can have at
>>> -	 * most 255 32B range descriptors plus a 64B header.
>>> +	 * most 255 32B range descriptors plus a 64B header. This log varies in
>>> +	 * size, so use the size reported in the GPL directory. Reading beyond
>>> +	 * the supported length will result in an error.
>>>    	 */
>>> -	buf_len = (64 + 255 * 32 + 511) & ~511;
>>> +	buf_len <<= 9;
>>>    	buf = kzalloc(buf_len, GFP_KERNEL);
>>>    	if (!buf)
>>>    		goto out;
>>
>> I don't get it.
>> You just returned the actual length of the log page from the previous
>> function. Why do you need to calculate the length here?
> 
> Calculate ? This is only converting from 512B sectors to bytes.
> The calculation was mine, a gross error :) This is what this patch is fixing.
> 
Sigh. Can't we have a 'bytes_to_sectors' helper? All this shifting by 9 
is getting on my nerves ...

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		           Kernel Storage Architect
hare@suse.de			                  +49 911 74053 688
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