Question

I am very new to Linux programming so bear with me. I have 2 thread type that perform different operations so I want each one to have it’s own mutex. Here is the code I am using , is it good ? If not why ?

static pthread_mutex_t cs_mutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_mutex_t cs_mutex2 = PTHREAD_MUTEX_INITALIZER;

void * Thread1(void * lp)
{
    int * sock = (int*)lp;
    char buffer[2024];

    int bytecount = recv(*sock, buffer, 2048, 0);
    while (0 == 0)
    {
        if ((bytecount ==0) || (bytecount == -1))
        {
        pthread_mutex_lock(&cs_mutex);

                  //Some uninteresting operations witch plays with set 1 of global variables;
        pthread_mutex_unlock(&cs_mutex);
        }
    }
}

void * Thread2(void * lp)
{   
    while (0 == 0)
    {
        pthread_mutex_lock(&cs_mutex2);
            //Some uninteresting operations witch plays with some global variables;
        pthread_mutex_unlock(&cs_mutex2);
    }
}

Answer 1

Normally, a mutex is not thread related.
It ensures that a critical area is only accessed by a single thread.
So if u have some shared areas, like processing the same array by multiple threads, then you must ensure exclusive access for this area.
That means, you do not need a mutex for each thread. You need a mutex for the critical area.