static struct kmem_cache *userfaultfd_ctx_cachep __read_mostly;
-enum userfaultfd_state {
- UFFD_STATE_WAIT_API,
- UFFD_STATE_RUNNING,
-};
-
/*
* Start with fault_pending_wqh and fault_wqh so they're more likely
* to be in the same cacheline.
unsigned int flags;
/* features requested from the userspace */
unsigned int features;
- /* state machine */
- enum userfaultfd_state state;
/* released */
bool released;
/* memory mappings are changing because of non-cooperative event */
- bool mmap_changing;
+ atomic_t mmap_changing;
/* mm with one ore more vmas attached to this userfaultfd_ctx */
struct mm_struct *mm;
};
unsigned long len;
};
+/* internal indication that UFFD_API ioctl was successfully executed */
+#define UFFD_FEATURE_INITIALIZED (1u << 31)
+
+static bool userfaultfd_is_initialized(struct userfaultfd_ctx *ctx)
+{
+ return ctx->features & UFFD_FEATURE_INITIALIZED;
+}
+
static int userfaultfd_wake_function(wait_queue_entry_t *wq, unsigned mode,
int wake_flags, void *key)
{
* already released.
*/
out:
- WRITE_ONCE(ctx->mmap_changing, false);
+ atomic_dec(&ctx->mmap_changing);
+ VM_BUG_ON(atomic_read(&ctx->mmap_changing) < 0);
userfaultfd_ctx_put(ctx);
}
refcount_set(&ctx->refcount, 1);
ctx->flags = octx->flags;
- ctx->state = UFFD_STATE_RUNNING;
ctx->features = octx->features;
ctx->released = false;
- ctx->mmap_changing = false;
+ atomic_set(&ctx->mmap_changing, 0);
ctx->mm = vma->vm_mm;
mmgrab(ctx->mm);
userfaultfd_ctx_get(octx);
- WRITE_ONCE(octx->mmap_changing, true);
+ atomic_inc(&octx->mmap_changing);
fctx->orig = octx;
fctx->new = ctx;
list_add_tail(&fctx->list, fcs);
if (ctx->features & UFFD_FEATURE_EVENT_REMAP) {
vm_ctx->ctx = ctx;
userfaultfd_ctx_get(ctx);
- WRITE_ONCE(ctx->mmap_changing, true);
+ atomic_inc(&ctx->mmap_changing);
} else {
/* Drop uffd context if remap feature not enabled */
vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
return true;
userfaultfd_ctx_get(ctx);
- WRITE_ONCE(ctx->mmap_changing, true);
+ atomic_inc(&ctx->mmap_changing);
mmap_read_unlock(mm);
msg_init(&ewq.msg);
return -ENOMEM;
userfaultfd_ctx_get(ctx);
- WRITE_ONCE(ctx->mmap_changing, true);
+ atomic_inc(&ctx->mmap_changing);
unmap_ctx->ctx = ctx;
unmap_ctx->start = start;
unmap_ctx->end = end;
poll_wait(file, &ctx->fd_wqh, wait);
- switch (ctx->state) {
- case UFFD_STATE_WAIT_API:
+ if (!userfaultfd_is_initialized(ctx))
return EPOLLERR;
- case UFFD_STATE_RUNNING:
- /*
- * poll() never guarantees that read won't block.
- * userfaults can be waken before they're read().
- */
- if (unlikely(!(file->f_flags & O_NONBLOCK)))
- return EPOLLERR;
- /*
- * lockless access to see if there are pending faults
- * __pollwait last action is the add_wait_queue but
- * the spin_unlock would allow the waitqueue_active to
- * pass above the actual list_add inside
- * add_wait_queue critical section. So use a full
- * memory barrier to serialize the list_add write of
- * add_wait_queue() with the waitqueue_active read
- * below.
- */
- ret = 0;
- smp_mb();
- if (waitqueue_active(&ctx->fault_pending_wqh))
- ret = EPOLLIN;
- else if (waitqueue_active(&ctx->event_wqh))
- ret = EPOLLIN;
- return ret;
- default:
- WARN_ON_ONCE(1);
+ /*
+ * poll() never guarantees that read won't block.
+ * userfaults can be waken before they're read().
+ */
+ if (unlikely(!(file->f_flags & O_NONBLOCK)))
return EPOLLERR;
- }
+ /*
+ * lockless access to see if there are pending faults
+ * __pollwait last action is the add_wait_queue but
+ * the spin_unlock would allow the waitqueue_active to
+ * pass above the actual list_add inside
+ * add_wait_queue critical section. So use a full
+ * memory barrier to serialize the list_add write of
+ * add_wait_queue() with the waitqueue_active read
+ * below.
+ */
+ ret = 0;
+ smp_mb();
+ if (waitqueue_active(&ctx->fault_pending_wqh))
+ ret = EPOLLIN;
+ else if (waitqueue_active(&ctx->event_wqh))
+ ret = EPOLLIN;
+
+ return ret;
}
static const struct file_operations userfaultfd_fops;
int no_wait = file->f_flags & O_NONBLOCK;
struct inode *inode = file_inode(file);
- if (ctx->state == UFFD_STATE_WAIT_API)
+ if (!userfaultfd_is_initialized(ctx))
return -EINVAL;
for (;;) {
user_uffdio_copy = (struct uffdio_copy __user *) arg;
ret = -EAGAIN;
- if (READ_ONCE(ctx->mmap_changing))
+ if (atomic_read(&ctx->mmap_changing))
goto out;
ret = -EFAULT;
user_uffdio_zeropage = (struct uffdio_zeropage __user *) arg;
ret = -EAGAIN;
- if (READ_ONCE(ctx->mmap_changing))
+ if (atomic_read(&ctx->mmap_changing))
goto out;
ret = -EFAULT;
struct userfaultfd_wake_range range;
bool mode_wp, mode_dontwake;
- if (READ_ONCE(ctx->mmap_changing))
+ if (atomic_read(&ctx->mmap_changing))
return -EAGAIN;
user_uffdio_wp = (struct uffdio_writeprotect __user *) arg;
user_uffdio_continue = (struct uffdio_continue __user *)arg;
ret = -EAGAIN;
- if (READ_ONCE(ctx->mmap_changing))
+ if (atomic_read(&ctx->mmap_changing))
goto out;
ret = -EFAULT;
static inline unsigned int uffd_ctx_features(__u64 user_features)
{
/*
- * For the current set of features the bits just coincide
+ * For the current set of features the bits just coincide. Set
+ * UFFD_FEATURE_INITIALIZED to mark the features as enabled.
*/
- return (unsigned int)user_features;
+ return (unsigned int)user_features | UFFD_FEATURE_INITIALIZED;
}
/*
{
struct uffdio_api uffdio_api;
void __user *buf = (void __user *)arg;
+ unsigned int ctx_features;
int ret;
__u64 features;
- ret = -EINVAL;
- if (ctx->state != UFFD_STATE_WAIT_API)
- goto out;
ret = -EFAULT;
if (copy_from_user(&uffdio_api, buf, sizeof(uffdio_api)))
goto out;
ret = -EFAULT;
if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api)))
goto out;
- ctx->state = UFFD_STATE_RUNNING;
+
/* only enable the requested features for this uffd context */
- ctx->features = uffd_ctx_features(features);
+ ctx_features = uffd_ctx_features(features);
+ ret = -EINVAL;
+ if (cmpxchg(&ctx->features, 0, ctx_features) != 0)
+ goto err_out;
+
ret = 0;
out:
return ret;
int ret = -EINVAL;
struct userfaultfd_ctx *ctx = file->private_data;
- if (cmd != UFFDIO_API && ctx->state == UFFD_STATE_WAIT_API)
+ if (cmd != UFFDIO_API && !userfaultfd_is_initialized(ctx))
return -EINVAL;
switch(cmd) {
refcount_set(&ctx->refcount, 1);
ctx->flags = flags;
ctx->features = 0;
- ctx->state = UFFD_STATE_WAIT_API;
ctx->released = false;
- ctx->mmap_changing = false;
+ atomic_set(&ctx->mmap_changing, 0);
ctx->mm = current->mm;
/* prevent the mm struct to be freed */
mmgrab(ctx->mm);
projects / linux-2.6-microblaze.git / blobdiff