Problem with SIMPLEQ_INSERT_TAIL

[Stephan]

Hello,

I am working on the semaphore part of my Haiku compat layer. I took
uipc_sem.c as a reference, where control structures are organized in a
dynamically allocated array and not as part of a list.

However, I like to maintain a "free list" in the form of a SIMPLEQ, on
which unused semaphores are maintained for fast allocation.

There is an issue in the initialization function, where each structure
is inserted into the free queue. I spent some time on this, but have
been unable to find the cause. Maybe I am overlooking something
trivial or there is something special I just don´t know.

The compiler says:

In file included from /home/stephan/src/sys/sys/siginfo.h:38,
                 from /home/stephan/src/sys/sys/signal.h:112,
                 from ./machine/frame.h:75,
                 from ./x86/cpu.h:56,
                 from ./machine/cpu.h:42,
                 from ./machine/param.h:11,
                 from /home/stephan/src/sys/sys/param.h:142,
                 from /home/stephan/src/sys/kern/uipc_hsem.c:32:
/home/stephan/src/sys/kern/uipc_hsem.c: In function 'khsem_init':
/home/stephan/src/sys/sys/queue.h:347:19: error: assignment to 'struct
khsem **' from incompatible pointer type 'struct kshem **'
[-Werror=incompatible-pointer-types]
  347 |  (head)->sqh_last = &(elm)->field.sqe_next;   \
      |                   ^
/home/stephan/src/sys/kern/uipc_hsem.c:68:9: note: in expansion of
macro 'SIMPLEQ_INSERT_TAIL'
   68 |         SIMPLEQ_INSERT_TAIL(&khsem_freeq, &hsems[i], khs_entry);
      |         ^~~~~~~~~~~~~~~~~~~



The relevant code snippet is this:

const int khsem_max = 8192;

static kmutex_t                 khsem_mutex               __cacheline_aligned;
static struct khsem             *hsems                    __read_mostly;
static SIMPLEQ_HEAD(, khsem)    khsem_freeq;


int
khsem_init(void)
{
    int i, sz;

    SIMPLEQ_INIT(&khsem_freeq);
    mutex_init(&khsem_mutex, MUTEX_DEFAULT, IPL_NONE);

    sz = ALIGN(khsem_max * sizeof(struct khsem));
    sz = round_page(sz);

    // XXX allocate memory

    for (i = 0; i < khsem_max; i++) {
        hsems[i].khs_id = i;
        mutex_init(&hsems[i].khs_interlock, MUTEX_DEFAULT, IPL_NONE);
        cv_init(&hsems[i].khs_cv, "acquire_sem");

        SIMPLEQ_INSERT_TAIL(&khsem_freeq, &hsems[i], khs_entry); //
<<---- DOES NOT COMPILE
    }

}


The control structure looks like this:

struct khsem {
  sem_id                  khs_id;             /* id of this semaphore */
  SIMPLEQ_ENTRY(kshem)    khs_entry;          /* free list entry */
  kmutex_t                khs_interlock;      /* lock on this semaphore */
  kcondvar_t              khs_cv;             /* CV for wait events */
  pid_t                   khs_owner;          /* owning process */
  char                    *khs_name;          /* name of this semaphore */
  size_t                  khs_namelen;        /* length of name */
  int                     khs_state;          /* state of this port */
  int                     khs_waiters;
  int                     khs_count;          /* current count */
  lwpid_t                 khs_latest_holder;  /* latest holder LWP id */
  uid_t                   khs_uid;            /* creator uid */
  gid_t                   khs_gid;            /* creator gid */
};



Any help is appreciated ;)

Thanks,

Stephan