Re: [PATCH] svc_run: make sure only one svc_run loop runs in one process

[Xiubo Li <xiubli@redhat.com>]

On 2019/6/11 22:54, Steve Dickson wrote:
> Sorry for the delay....
>
> On 5/15/19 10:55 PM, Xiubo Li wrote:
>> Hey ping.
>>
>> What's the state of this patch and will it make sense here?
> I'm not sure it does make sense.... Shouldn't the mutex lock
> be in the call of svc_run()?

Hi Steve,

Yeah, mutex lock should be in the call of svc_run(). This is exactly 
what I do in this change.

If the libtirpc means to allow only one svc_run() loop in each process, 
so IMO this change is needed. Or if we will allow more than one like the 
glibc version does, so this should be one bug in libtirpc.

Thanks.
BRs
Xiubo


> steved.
>
>> Thanks
>> BRs
>>
>> On 2019/4/9 19:37, xiubli@redhat.com wrote:
>>> From: Xiubo Li <xiubli@redhat.com>
>>>
>>> In gluster-block project and there are 2 separate threads, both
>>> of which will run the svc_run loop, this could work well in glibc
>>> version, but in libtirpc we are hitting the random crash and stuck
>>> issues.
>>>
>>> More detail please see:
>>> https://github.com/gluster/gluster-block/pull/182
>>>
>>> Signed-off-by: Xiubo Li <xiubli@redhat.com>
>>> ---
>>>    src/svc_run.c | 19 +++++++++++++++++++
>>>    1 file changed, 19 insertions(+)
>>>
>>> diff --git a/src/svc_run.c b/src/svc_run.c
>>> index f40314b..b295755 100644
>>> --- a/src/svc_run.c
>>> +++ b/src/svc_run.c
>>> @@ -38,12 +38,17 @@
>>>    #include <string.h>
>>>    #include <unistd.h>
>>>    #include <sys/poll.h>
>>> +#include <syslog.h>
>>> +#include <stdbool.h>
>>>        #include <rpc/rpc.h>
>>>    #include "rpc_com.h"
>>>    #include <sys/select.h>
>>>    +static bool svc_loop_running = false;
>>> +static pthread_mutex_t svc_run_lock = PTHREAD_MUTEX_INITIALIZER;
>>> +
>>>    void
>>>    svc_run()
>>>    {
>>> @@ -51,6 +56,16 @@ svc_run()
>>>      struct pollfd *my_pollfd = NULL;
>>>      int last_max_pollfd = 0;
>>>    +  pthread_mutex_lock(&svc_run_lock);
>>> +  if (svc_loop_running) {
>>> +    pthread_mutex_unlock(&svc_run_lock);
>>> +    syslog (LOG_ERR, "svc_run: svc loop is already running in current process %d", getpid());
>>> +    return;
>>> +  }
>>> +
>>> +  svc_loop_running = true;
>>> +  pthread_mutex_unlock(&svc_run_lock);
>>> +
>>>      for (;;) {
>>>        int max_pollfd = svc_max_pollfd;
>>>        if (max_pollfd == 0 && svc_pollfd == NULL)
>>> @@ -111,4 +126,8 @@ svc_exit()
>>>        svc_pollfd = NULL;
>>>        svc_max_pollfd = 0;
>>>        rwlock_unlock(&svc_fd_lock);
>>> +
>>> +    pthread_mutex_lock(&svc_run_lock);
>>> +    svc_loop_running = false;
>>> +    pthread_mutex_unlock(&svc_run_lock);
>>>    }
>>
>>
>>
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