error: expected expression before ‘{’ token in pthread rw_lock - c

Question

So i have this code of a node in an kinda of a data structure and the node has a read write lock
to initialize the lock i used pthread_rwlock_init before using pthread_rwlock_t rwlock = PTHREAD_RWLOCK_INITIALIZER;
the thing is for some reason it gives an error saying that it was expected an expression before the PTHREAD_RWLOCK_INITIALIZER and i dont understand what it is because i know im not missing any ;
Code:
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "state.h"
#include <pthread.h>
typedef struct inode_t {
type nodeType;
union Data data;
// ******************NEW ATTRIBUTE THAT INLCUDES THE LOCK *******************************
pthread_rwlock_t lock;
} inode_t;
void inode_table_init() {
for (int i = 0; i < INODE_TABLE_SIZE; i++) {
inode_table[i].nodeType = T_NONE;
inode_table[i].data.dirEntries = NULL;
inode_table[i].data.fileContents = NULL;
// ****************** NEW *******************************
// Initializes the lock
pthread_rwlock_init(&inode_table[i].lock ,NULL);
inode_table[i].lock = PTHREAD_RWLOCK_INITIALIZER;
}
}
int inode_create(type nType) {
/* Used for testing synchronization speedup */
insert_delay(DELAY);
for (int inumber = 0; inumber < INODE_TABLE_SIZE; inumber++) {
if (inode_table[inumber].nodeType == T_NONE) {
inode_table[inumber].nodeType = nType;
pthread_rwlock_init(&inode_table[inumber].lock ,NULL);
inode_table[inumber].lock = PTHREAD_RWLOCK_INITIALIZER;
if (nType == T_DIRECTORY) {
/* Initializes entry table */
inode_table[inumber].data.dirEntries = malloc(sizeof(DirEntry) * MAX_DIR_ENTRIES);
for (int i = 0; i < MAX_DIR_ENTRIES; i++) {
inode_table[inumber].data.dirEntries[i].inumber = FREE_INODE;
}
}
else {
inode_table[inumber].data.fileContents = NULL;
}
return inumber;
}
}
return FAIL;
}
Well it doesnt matter what the function does what it matters is that im having a strange error in the lines that im initializing the locks
Error:
fs/state.c: In function ‘inode_table_init’:
fs/state.c:34:31: error: expected expression before ‘{’ token
inode_table[i].lock = PTHREAD_RWLOCK_INITIALIZER;
^
fs/state.c: In function ‘inode_create’:
fs/state.c:81:41: error: expected expression before ‘{’ token
inode_table[inumber].lock = PTHREAD_RWLOCK_INITIALIZER;
Well any help would be appreciated.

Answer 1

You don't need those assignments. From the POSIX spec:
In cases where default read-write lock attributes are appropriate, the macro PTHREAD_RWLOCK_INITIALIZER can be used to initialise read-write locks that are statically allocated. The effect is equivalent to dynamic initialisation by a call to pthread_rwlock_init() with the parameter attr specified as NULL, except that no error checks are performed.
You can only use it in a variable initialization, not an assignment. And since it's equivalent to the calls on the lines before, it's redundant even it worked.