mop3/kernel/proc/mutex.c

#include <libk/assert.h>
#include <libk/rbtree.h>
#include <libk/std.h>
#include <libk/string.h>
#include <proc/mutex.h>
#include <proc/proc.h>
#include <sync/spin_lock.h>
#include <sys/debug.h>

bool proc_create_resource_mutex (struct proc_mutex* mutex) {
  memset (mutex, 0, sizeof (*mutex));

  return true;
}

void proc_cleanup_resource_mutex (struct proc* proc, struct proc_resource* resource) {
  struct proc_mutex* mutex = &resource->u.mutex;

  proc_mutex_unlock (proc, mutex);
}

void proc_mutex_lock (struct proc* proc, struct proc_mutex* mutex) {
  spin_lock_ctx_t ctxmt;

try:
  spin_lock (&mutex->resource->lock, &ctxmt);

  if (!mutex->locked || mutex->owner == proc) {
    mutex->locked = true;
    mutex->owner = proc;
    spin_unlock (&mutex->resource->lock, &ctxmt);
    return;
  }

  spin_unlock (&mutex->resource->lock, &ctxmt);

  proc_suspend (proc, &mutex->suspension_q);

  goto try;
}

bool proc_mutex_unlock (struct proc* proc, struct proc_mutex* mutex) {
  spin_lock_ctx_t ctxmt, ctxsq;

  spin_lock (&mutex->resource->lock, &ctxmt);

  if (mutex->owner != proc) {
    spin_unlock (&mutex->resource->lock, &ctxmt);
    return false;
  }

  spin_lock (&mutex->suspension_q.lock, &ctxsq);

  struct proc* resumed_proc = NULL;
  struct rb_node_link* node;
  rbtree_first (&mutex->suspension_q.proc_tree, node);

  if (node) {
    resumed_proc = rbtree_entry (node, struct proc, suspension_link);
    mutex->owner = resumed_proc;
    mutex->locked = true;

    spin_unlock (&mutex->suspension_q.lock, &ctxsq);
    spin_unlock (&mutex->resource->lock, &ctxmt);

    proc_resume (resumed_proc);

    return true;
  }

  mutex->locked = false;
  mutex->owner = NULL;

  spin_unlock (&mutex->suspension_q.lock, &ctxsq);
  spin_unlock (&mutex->resource->lock, &ctxmt);

  return true;
}