NT waits can optionally be made "alertable". This is a special channel for thread wakeup that is mildly similar to SIGIO. A thread has an internal single bit of "alerted" state, and if a thread is alerted while an alertable wait, the wait will return a special value, consume the "alerted" state, and will not consume any of its objects.
Alerts are implemented using events; the user-space NT emulator is expected to create an internal ntsync event for each thread and pass that event to wait functions.
Signed-off-by: Elizabeth Figura zfigura@codeweavers.com --- drivers/misc/ntsync.c | 70 ++++++++++++++++++++++++++++++++----- include/uapi/linux/ntsync.h | 3 +- 2 files changed, 63 insertions(+), 10 deletions(-)
diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c index 78dc405bb759..457ff28b789f 100644 --- a/drivers/misc/ntsync.c +++ b/drivers/misc/ntsync.c @@ -869,22 +869,29 @@ static int setup_wait(struct ntsync_device *dev, const struct ntsync_wait_args *args, bool all, struct ntsync_q **ret_q) { + int fds[NTSYNC_MAX_WAIT_COUNT + 1]; const __u32 count = args->count; - int fds[NTSYNC_MAX_WAIT_COUNT]; struct ntsync_q *q; + __u32 total_count; __u32 i, j;
- if (args->pad[0] || args->pad[1] || (args->flags & ~NTSYNC_WAIT_REALTIME)) + if (args->pad || (args->flags & ~NTSYNC_WAIT_REALTIME)) return -EINVAL;
if (args->count > NTSYNC_MAX_WAIT_COUNT) return -EINVAL;
+ total_count = count; + if (args->alert) + total_count++; + if (copy_from_user(fds, u64_to_user_ptr(args->objs), array_size(count, sizeof(*fds)))) return -EFAULT; + if (args->alert) + fds[count] = args->alert;
- q = kmalloc(struct_size(q, entries, count), GFP_KERNEL); + q = kmalloc(struct_size(q, entries, total_count), GFP_KERNEL); if (!q) return -ENOMEM; q->task = current; @@ -894,7 +901,7 @@ static int setup_wait(struct ntsync_device *dev, q->ownerdead = false; q->count = count;
- for (i = 0; i < count; i++) { + for (i = 0; i < total_count; i++) { struct ntsync_q_entry *entry = &q->entries[i]; struct ntsync_obj *obj = get_obj(dev, fds[i]);
@@ -944,10 +951,10 @@ static void try_wake_any_obj(struct ntsync_obj *obj) static int ntsync_wait_any(struct ntsync_device *dev, void __user *argp) { struct ntsync_wait_args args; + __u32 i, total_count; struct ntsync_q *q; int signaled; bool all; - __u32 i; int ret;
if (copy_from_user(&args, argp, sizeof(args))) @@ -957,9 +964,13 @@ static int ntsync_wait_any(struct ntsync_device *dev, void __user *argp) if (ret < 0) return ret;
+ total_count = args.count; + if (args.alert) + total_count++; + /* queue ourselves */
- for (i = 0; i < args.count; i++) { + for (i = 0; i < total_count; i++) { struct ntsync_q_entry *entry = &q->entries[i]; struct ntsync_obj *obj = entry->obj;
@@ -968,9 +979,15 @@ static int ntsync_wait_any(struct ntsync_device *dev, void __user *argp) ntsync_unlock_obj(dev, obj, all); }
- /* check if we are already signaled */ + /* + * Check if we are already signaled. + * + * Note that the API requires that normal objects are checked before + * the alert event. Hence we queue the alert event last, and check + * objects in order. + */
- for (i = 0; i < args.count; i++) { + for (i = 0; i < total_count; i++) { struct ntsync_obj *obj = q->entries[i].obj;
if (atomic_read(&q->signaled) != -1) @@ -987,7 +1004,7 @@ static int ntsync_wait_any(struct ntsync_device *dev, void __user *argp)
/* and finally, unqueue */
- for (i = 0; i < args.count; i++) { + for (i = 0; i < total_count; i++) { struct ntsync_q_entry *entry = &q->entries[i]; struct ntsync_obj *obj = entry->obj;
@@ -1047,6 +1064,14 @@ static int ntsync_wait_all(struct ntsync_device *dev, void __user *argp) */ list_add_tail(&entry->node, &obj->all_waiters); } + if (args.alert) { + struct ntsync_q_entry *entry = &q->entries[args.count]; + struct ntsync_obj *obj = entry->obj; + + dev_lock_obj(dev, obj); + list_add_tail(&entry->node, &obj->any_waiters); + dev_unlock_obj(dev, obj); + }
/* check if we are already signaled */
@@ -1054,6 +1079,21 @@ static int ntsync_wait_all(struct ntsync_device *dev, void __user *argp)
mutex_unlock(&dev->wait_all_lock);
+ /* + * Check if the alert event is signaled, making sure to do so only + * after checking if the other objects are signaled. + */ + + if (args.alert) { + struct ntsync_obj *obj = q->entries[args.count].obj; + + if (atomic_read(&q->signaled) == -1) { + bool all = ntsync_lock_obj(dev, obj); + try_wake_any_obj(obj); + ntsync_unlock_obj(dev, obj, all); + } + } + /* sleep */
ret = ntsync_schedule(q, &args); @@ -1079,6 +1119,18 @@ static int ntsync_wait_all(struct ntsync_device *dev, void __user *argp)
mutex_unlock(&dev->wait_all_lock);
+ if (args.alert) { + struct ntsync_q_entry *entry = &q->entries[args.count]; + struct ntsync_obj *obj = entry->obj; + bool all; + + all = ntsync_lock_obj(dev, obj); + list_del(&entry->node); + ntsync_unlock_obj(dev, obj, all); + + put_obj(obj); + } + signaled = atomic_read(&q->signaled); if (signaled != -1) { struct ntsync_wait_args __user *user_args = argp; diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h index b9d208a8c00f..6d06793512b1 100644 --- a/include/uapi/linux/ntsync.h +++ b/include/uapi/linux/ntsync.h @@ -34,7 +34,8 @@ struct ntsync_wait_args { __u32 index; __u32 flags; __u32 owner; - __u32 pad[2]; + __u32 alert; + __u32 pad; };
#define NTSYNC_MAX_WAIT_COUNT 64