Re: [Xen-devel] [PATCH v2] xen/blkfront: fix ring info addressing

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

On 05/03/2020 14:40, Jürgen Groß wrote:
> On 05.03.20 13:42, Roger Pau Monné wrote:
>> On Thu, Mar 05, 2020 at 12:40:44PM +0100, Juergen Gross wrote:
>>> Commit 0265d6e8ddb890 ("xen/blkfront: limit allocated memory size to
>>> actual use case") made struct blkfront_ring_info size dynamic. This is
>>> fine when running with only one queue, but with multiple queues the
>>> addressing of the single queues has to be adapted as the structs are
>>> allocated in an array.
>>>
>>> Fixes: 0265d6e8ddb890 ("xen/blkfront: limit allocated memory size to actual 
>>> use case")
>>> Reported-by: Sander Eikelenboom <linux@xxxxxxxxxxxxxx>
>>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
>>> ---
>>> V2:
>>> - get rid of rinfo_ptr() helper
>>> - use proper parenthesis in for_each_rinfo()
>>> - rename rinfo parameter of for_each_rinfo()
>>> ---
>>>   drivers/block/xen-blkfront.c | 79 
>>> +++++++++++++++++++++++---------------------
>>>   1 file changed, 42 insertions(+), 37 deletions(-)
>>>
>>> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
>>> index e2ad6bba2281..8e844da826db 100644
>>> --- a/drivers/block/xen-blkfront.c
>>> +++ b/drivers/block/xen-blkfront.c
>>> @@ -213,6 +213,7 @@ struct blkfront_info
>>>     struct blk_mq_tag_set tag_set;
>>>     struct blkfront_ring_info *rinfo;
>>>     unsigned int nr_rings;
>>> +   unsigned int rinfo_size;
>>>     /* Save uncomplete reqs and bios for migration. */
>>>     struct list_head requests;
>>>     struct bio_list bio_list;
>>> @@ -259,6 +260,18 @@ static int blkfront_setup_indirect(struct 
>>> blkfront_ring_info *rinfo);
>>>   static void blkfront_gather_backend_features(struct blkfront_info *info);
>>>   static int negotiate_mq(struct blkfront_info *info);
>>>   
>>> +#define for_each_rinfo(info, ptr, idx)                             \
>>> +   for ((ptr) = (info)->rinfo, (idx) = 0;                  \
>>> +        (idx) < (info)->nr_rings;                          \
>>> +        (idx)++, (ptr) = (void *)(ptr) + (info)->rinfo_size)
>>> +
>>> +static struct blkfront_ring_info *get_rinfo(struct blkfront_info *info,
>>
>> I still think inline should be added here, but I don't have such a
>> strong opinion to block the patch on it.
> 
> I can add it if you like that better. Won't make much difference in the
> end.
> 
>> Also, info should be constified AFAICT.
> 
> Yes.
> 
>>
>> With at least info constified:
>>
>> Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
>>
>> Can you queue this through the Xen tree?
> 
> Sure.
> 
> 
> Juergen
> 

Just tested v2 and it works for me, thanks !

--
Sander


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