reader writer code.txt

#20K-0134 20K-0355
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/delay.h>

int writer(void* data);
int reader(void* data);

DEFINE_SPINLOCK(mutex);
DEFINE_SPINLOCK(wrt);

char msg[256];
int numreader = 0;
int nread;
int val1 = 32;


int writer(void* data)
{  
spin_lock(&wrt);
int temp = val1;
val1 = val1 * 2;
printk("writer modified value %d to: %d ", temp , val1);
spin_unlock(&wrt);

return 0;

}

int reader(void* data)
{
   
spin_lock(&mutex);
numreader++;
if(numreader == 1) {
spin_lock(&wrt);
}
spin_unlock(&mutex);
printk("reader reads value %d", val1);

spin_lock(&mutex);
numreader--;
if(numreader == 0) {
spin_unlock(&wrt);
}
spin_unlock(&mutex);

return 0;
}


asmlinkage long sys_readerwriter(void)
{  

int i;
int numberOfReaders;
struct task_struct *myWriter[5];
numberOfReaders = 10;
struct task_struct *readers[10];



for(i = 0; i < 5; i++) {

myWriter[i] =kthread_create(writer, NULL, "writer_thread");

if(myWriter[i]){
wake_up_process(myWriter[i]);
}
else{
kthread_stop(myWriter[i]);
}
}


for(i = 0; i < 10; i++)
{

readers[i] = kthread_create(reader, NULL, "reader_thread");
if(readers[i]){
wake_up_process(readers[i]);
}
else{
kthread_stop(readers[i]);
}
}


return 0;
   
}