[dpdk-dev] [PATCH v7 1/1] fbarray: fix duplicated fbarray file in secondary

[Yasufumi Ogawa]

Hi Anatoly,

On 2019/11/27 19:26, Burakov, Anatoly wrote:
> On 26-Nov-19 7:40 PM, Yasufumi Ogawa wrote:
>> Hi David,
>>
>> Sorry for slow reply.
>>
>> On 2019/11/14 21:27, David Marchand wrote:
>>> On Thu, Nov 14, 2019 at 12:42 PM Yasufumi Ogawa <yasufum.o at gmail.com> 
>>> wrote:
>>>>
>>>> On 2019/11/14 2:01, Burakov, Anatoly wrote:
>>>>> On 13-Nov-19 9:43 PM, yasufum.o at gmail.com wrote:
>>>>>> From: Yasufumi Ogawa <ogawa.yasufumi at lab.ntt.co.jp>
>>>>>>
>>>>>> In secondary_msl_create_walk(), it creates a file for fbarrays 
>>>>>> with its
>>>>>> PID for reserving unique name among secondary processes. However, it
>>>>>> does not work if several secondaries run as app containers because 
>>>>>> each
>>>>>> of containerized secondary has PID 1, and failed to reserve unique 
>>>>>> name
>>>>>> other than first one. To reserve unique name in each of 
>>>>>> containers, use
>>>>>> hostname in addition to PID.
>>>>>>
>>>>>> Cc: stable at dpdk.org
>>>>>>
>>>>>> Signed-off-by: Yasufumi Ogawa <yasufum.o at gmail.com>
>>>>>> ---
>>>>>>    lib/librte_eal/linux/eal/eal_memalloc.c | 16 +++++++++++++---
>>>>>>    1 file changed, 13 insertions(+), 3 deletions(-)
>>>>>>
>>>>>> diff --git a/lib/librte_eal/linux/eal/eal_memalloc.c
>>>>>> b/lib/librte_eal/linux/eal/eal_memalloc.c
>>>>>> index af6d0d023..11de6d4d6 100644
>>>>>> --- a/lib/librte_eal/linux/eal/eal_memalloc.c
>>>>>> +++ b/lib/librte_eal/linux/eal/eal_memalloc.c
>>>>>> @@ -1365,6 +1365,12 @@ secondary_msl_create_walk(const struct
>>>>>> rte_memseg_list *msl,
>>>>>>        struct rte_memseg_list *primary_msl, *local_msl;
>>>>>>        char name[PATH_MAX];
>>>>>>        int msl_idx, ret;
>>>>>> +    char hostname[HOST_NAME_MAX+1] = { 0 };
>>>>>> +    /* filename of secondary's fbarray is defined such as
>>>>>> +     * "fbarray_memseg-1048576k-0-0_PID_HOSTNAME" and length of PID
>>>>>> +     * can be 7 digits maximumly.
>>>>>> +     */
>>>>>> +    int fbarray_sec_name_len = 32 + 7 + 1 + HOST_NAME_MAX + 1;
>>>>>
>>>>> What does 32 stand for? Maybe #define both 32 and 7 values?
>>>> Hi Anatoly,
>>>>
>>>> Thank you for your comments! If my understanding is correct, the prefix
>>>> "fbarray_memseg-1048576k-0-0_" is 28 digits and it could be larger if
>>>> using the size of hugepage or the number of NUMA nodes are larger
>>>> possibly. However, I think 32 digits is still enough.
>>>>
>>>>   > Maybe #define both 32 and 7 values?
>>>> Yes. I think it should be better to use #define if this values are
>>>> referred several times.
>>>
>>>
>>> We can truncate to RTE_FBARRAY_NAME_LEN in all cases.
>>> And iiuc, rte_fbarray_init will refuse any longer name anyway.
>> Could I confirm the issue? I've understood that it is failed to 
>> validate the name of fbarray in fully_validate() at 
>> "lib/librte_eal/common/eal_common_fbarray.c:697".
>>
>> static int
>> fully_validate(const char *name, unsigned int elt_sz, unsigned int len)
>> {
>>          if (name == NULL || elt_sz == 0 || len == 0 || len > INT_MAX) {
>>                  rte_errno = EINVAL;
>>                  return -1;
>>          }
>>
>>          if (strnlen(name, RTE_FBARRAY_NAME_LEN) == 
>> RTE_FBARRAY_NAME_LEN) {
>>                  rte_errno = ENAMETOOLONG;
>>                  return -1;
>>          }
>>          return 0;
>> }
>>
>> I should overwrite the definition of RTE_FBARRAY_NAME_LEN as previous 
>> patch in this case, and it causes an ABI breakage, right? If so, I 
>> would like to make the change and give up to update stable release.
>>
>> Thanks,
>> Yasufumi
>>
> 
> It seems we're getting into bikeshedding...
> 
> We can do this without ABI breakage. You could have just used 
> RTE_FBARRAY_NAME_LEN as max fbarray name length for fbarray_sec_name_len 
> (i.e. that would include hostname + pid + whatever else there is). The 
> name, as David has pointed out, would be truncated to 
> RTE_FBARRAY_NAME_LEN anyway (or, more precisely, it will be refused if 
> it's longer than that), so this is the most you can have - so you can 
> just use that as the maximum.
I sent v8 patch to change the size of RTE_FBARRAY_NAME_LEN itself to be 
allowed the size of secondary's fbarray over 64 bytes. I appreciate if 
you agree that.

Thanks,
Yasufumi