188 lines
5.2 KiB
Diff
188 lines
5.2 KiB
Diff
From 2c391d57d1393cd46bf8bab08232ddc3dd32d5e5 Mon Sep 17 00:00:00 2001
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From: Elizabeth Figura <zfigura@codeweavers.com>
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Date: Sun, 19 May 2024 15:24:39 -0500
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Subject: ntsync: Introduce alertable waits.
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NT waits can optionally be made "alertable". This is a special channel for
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thread wakeup that is mildly similar to SIGIO. A thread has an internal single
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bit of "alerted" state, and if a thread is alerted while an alertable wait, the
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wait will return a special value, consume the "alerted" state, and will not
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consume any of its objects.
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Alerts are implemented using events; the user-space NT emulator is expected to
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create an internal ntsync event for each thread and pass that event to wait
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functions.
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Signed-off-by: Elizabeth Figura <zfigura@codeweavers.com>
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---
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drivers/misc/ntsync.c | 70 ++++++++++++++++++++++++++++++++-----
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include/uapi/linux/ntsync.h | 3 +-
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2 files changed, 63 insertions(+), 10 deletions(-)
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--- a/drivers/misc/ntsync.c
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+++ b/drivers/misc/ntsync.c
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@@ -884,22 +884,29 @@ static int setup_wait(struct ntsync_devi
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const struct ntsync_wait_args *args, bool all,
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struct ntsync_q **ret_q)
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{
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+ int fds[NTSYNC_MAX_WAIT_COUNT + 1];
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const __u32 count = args->count;
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- int fds[NTSYNC_MAX_WAIT_COUNT];
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struct ntsync_q *q;
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+ __u32 total_count;
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__u32 i, j;
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- if (args->pad[0] || args->pad[1] || (args->flags & ~NTSYNC_WAIT_REALTIME))
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+ if (args->pad || (args->flags & ~NTSYNC_WAIT_REALTIME))
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return -EINVAL;
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if (args->count > NTSYNC_MAX_WAIT_COUNT)
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return -EINVAL;
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+ total_count = count;
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+ if (args->alert)
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+ total_count++;
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+
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if (copy_from_user(fds, u64_to_user_ptr(args->objs),
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array_size(count, sizeof(*fds))))
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return -EFAULT;
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+ if (args->alert)
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+ fds[count] = args->alert;
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- q = kmalloc(struct_size(q, entries, count), GFP_KERNEL);
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+ q = kmalloc(struct_size(q, entries, total_count), GFP_KERNEL);
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if (!q)
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return -ENOMEM;
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q->task = current;
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@@ -909,7 +916,7 @@ static int setup_wait(struct ntsync_devi
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q->ownerdead = false;
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q->count = count;
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- for (i = 0; i < count; i++) {
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+ for (i = 0; i < total_count; i++) {
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struct ntsync_q_entry *entry = &q->entries[i];
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struct ntsync_obj *obj = get_obj(dev, fds[i]);
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@@ -959,10 +966,10 @@ static void try_wake_any_obj(struct ntsy
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static int ntsync_wait_any(struct ntsync_device *dev, void __user *argp)
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{
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struct ntsync_wait_args args;
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+ __u32 i, total_count;
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struct ntsync_q *q;
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int signaled;
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bool all;
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- __u32 i;
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int ret;
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if (copy_from_user(&args, argp, sizeof(args)))
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@@ -972,9 +979,13 @@ static int ntsync_wait_any(struct ntsync
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if (ret < 0)
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return ret;
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+ total_count = args.count;
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+ if (args.alert)
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+ total_count++;
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+
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/* queue ourselves */
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- for (i = 0; i < args.count; i++) {
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+ for (i = 0; i < total_count; i++) {
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struct ntsync_q_entry *entry = &q->entries[i];
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struct ntsync_obj *obj = entry->obj;
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@@ -983,9 +994,15 @@ static int ntsync_wait_any(struct ntsync
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ntsync_unlock_obj(dev, obj, all);
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}
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- /* check if we are already signaled */
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+ /*
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+ * Check if we are already signaled.
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+ *
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+ * Note that the API requires that normal objects are checked before
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+ * the alert event. Hence we queue the alert event last, and check
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+ * objects in order.
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+ */
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- for (i = 0; i < args.count; i++) {
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+ for (i = 0; i < total_count; i++) {
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struct ntsync_obj *obj = q->entries[i].obj;
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if (atomic_read(&q->signaled) != -1)
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@@ -1002,7 +1019,7 @@ static int ntsync_wait_any(struct ntsync
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/* and finally, unqueue */
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- for (i = 0; i < args.count; i++) {
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+ for (i = 0; i < total_count; i++) {
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struct ntsync_q_entry *entry = &q->entries[i];
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struct ntsync_obj *obj = entry->obj;
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@@ -1062,6 +1079,14 @@ static int ntsync_wait_all(struct ntsync
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*/
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list_add_tail(&entry->node, &obj->all_waiters);
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}
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+ if (args.alert) {
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+ struct ntsync_q_entry *entry = &q->entries[args.count];
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+ struct ntsync_obj *obj = entry->obj;
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+
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+ dev_lock_obj(dev, obj);
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+ list_add_tail(&entry->node, &obj->any_waiters);
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+ dev_unlock_obj(dev, obj);
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+ }
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/* check if we are already signaled */
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@@ -1069,6 +1094,21 @@ static int ntsync_wait_all(struct ntsync
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mutex_unlock(&dev->wait_all_lock);
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+ /*
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+ * Check if the alert event is signaled, making sure to do so only
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+ * after checking if the other objects are signaled.
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+ */
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+
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+ if (args.alert) {
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+ struct ntsync_obj *obj = q->entries[args.count].obj;
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+
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+ if (atomic_read(&q->signaled) == -1) {
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+ bool all = ntsync_lock_obj(dev, obj);
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+ try_wake_any_obj(obj);
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+ ntsync_unlock_obj(dev, obj, all);
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+ }
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+ }
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+
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/* sleep */
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ret = ntsync_schedule(q, &args);
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@@ -1094,6 +1134,18 @@ static int ntsync_wait_all(struct ntsync
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mutex_unlock(&dev->wait_all_lock);
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+ if (args.alert) {
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+ struct ntsync_q_entry *entry = &q->entries[args.count];
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+ struct ntsync_obj *obj = entry->obj;
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+ bool all;
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+
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+ all = ntsync_lock_obj(dev, obj);
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+ list_del(&entry->node);
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+ ntsync_unlock_obj(dev, obj, all);
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+
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+ put_obj(obj);
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+ }
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+
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signaled = atomic_read(&q->signaled);
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if (signaled != -1) {
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struct ntsync_wait_args __user *user_args = argp;
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--- a/include/uapi/linux/ntsync.h
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+++ b/include/uapi/linux/ntsync.h
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@@ -37,7 +37,8 @@ struct ntsync_wait_args {
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__u32 index;
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__u32 flags;
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__u32 owner;
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- __u32 pad[2];
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+ __u32 alert;
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+ __u32 pad;
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};
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#define NTSYNC_MAX_WAIT_COUNT 64
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