Re: [dpdk-stable] [dpdk-dev] [PATCH v4] eal: fix proc type auto detection

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 12-Aug-19 11:03 AM, David Marchand wrote:
> On Wed, Jul 24, 2019 at 6:08 PM Anatoly Burakov
> <anatoly.burakov@intel.com> wrote:
>>
>> Currently, primary process holds an exclusive lock on the config
>> file, thereby preventing other primaries from spinning up. However,
>> when the primary dies, the lock is no longer being held, even though
>> there might be other secondary processes still running.
>>
>> The fix is two-fold. First of all, downgrade the primary process's
>> exclusive lock to a shared lock once we have it. Second of all,
>> also take out shared locks on the config from the secondaries. We
>> are using fcntl() locks, which get dropped when the file handle is
>> closed, so also remove the closure of config file handle.
>>
>> Fixes: af75078fece3 ("first public release")
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
>> ---

<snip>

>>          rte_mem_cfg_addr = mmap(NULL, sizeof(*rte_config.mem_config),
>>                                  PROT_READ, MAP_SHARED, mem_cfg_fd, 0);
>> @@ -330,8 +360,6 @@ rte_eal_config_reattach(void)
>>          mem_config = (struct rte_mem_config *) mmap(rte_mem_cfg_addr,
>>                          sizeof(*mem_config), PROT_READ | PROT_WRITE, MAP_SHARED,
>>                          mem_cfg_fd, 0);
>> -       close(mem_cfg_fd);
>> -       mem_cfg_fd = -1;
>>
>>          if (mem_config == MAP_FAILED) {
>>                  RTE_LOG(ERR, EAL, "Cannot mmap memory for rte_config! error %i (%s)\n",
> 
> We are missing a mem_cfg_fd cleanup if mmap failed.
> 

Good catch! Will fix.

> 
>> diff --git a/lib/librte_eal/linux/eal/eal.c b/lib/librte_eal/linux/eal/eal.c
>> index 34db78753..0f0726703 100644
>> --- a/lib/librte_eal/linux/eal/eal.c
>> +++ b/lib/librte_eal/linux/eal/eal.c
>> @@ -83,6 +83,13 @@ static struct flock wr_lock = {
>>                  .l_len = sizeof(early_mem_config.memsegs),
>>   };
>>
>> +static struct flock rd_lock = {
>> +       .l_type = F_RDLCK,

<snip>

>> -
>>          if (mem_config == MAP_FAILED || mem_config != rte_mem_cfg_addr) {
>>                  if (mem_config != MAP_FAILED) {
>>                          /* errno is stale, don't use */
> 
> Idem.
> 
> Reviewed-by: David Marchand <david.marchand@redhat.com>
> 
> With https://patchwork.dpdk.org/patch/56501/, the code is now really
> close between Linux and FreeBSD, could it go to common entirely?

I would prefer to keep them separate due to upcoming Windows port.

-- 
Thanks,
Anatoly