[src/trunk]: src/sys/external/bsd/drm2/dist/drm/nouveau Defer nouveau_fence_u...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/6fed98cf90d8
branches:  trunk
changeset: 992289:6fed98cf90d8
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Thu Aug 23 01:10:21 2018 +0000

description:
Defer nouveau_fence_unref until spin unlock.

- kfree while holding a spin lock is not a good idea.
- Make sure we GC every time we might signal fences.

PR kern/53441

XXX pullup-7
XXX pullup-8

diffstat:

 sys/external/bsd/drm2/dist/drm/nouveau/nouveau_fence.c |  77 ++++++++++++++++-
 sys/external/bsd/drm2/dist/drm/nouveau/nouveau_fence.h |   1 +
 2 files changed, 72 insertions(+), 6 deletions(-)

diffs (211 lines):

diff -r b3527a88d652 -r 6fed98cf90d8 sys/external/bsd/drm2/dist/drm/nouveau/nouveau_fence.c
--- a/sys/external/bsd/drm2/dist/drm/nouveau/nouveau_fence.c    Thu Aug 23 01:10:04 2018 +0000
+++ b/sys/external/bsd/drm2/dist/drm/nouveau/nouveau_fence.c    Thu Aug 23 01:10:21 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nouveau_fence.c,v 1.6 2018/08/23 01:10:04 riastradh Exp $      */
+/*     $NetBSD: nouveau_fence.c,v 1.7 2018/08/23 01:10:21 riastradh Exp $      */
 
 /*
  * Copyright (C) 2007 Ben Skeggs.
@@ -27,7 +27,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: nouveau_fence.c,v 1.6 2018/08/23 01:10:04 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: nouveau_fence.c,v 1.7 2018/08/23 01:10:21 riastradh Exp $");
 
 #include <sys/types.h>
 #include <sys/xcall.h>
@@ -87,6 +87,43 @@
 }
 
 /*
+ * nouveau_fence_gc_grab(fctx, list)
+ *
+ *     Move all of channel's done fences to list.
+ *
+ *     Caller must hold channel's fence lock.
+ */
+static void
+nouveau_fence_gc_grab(struct nouveau_fence_chan *fctx, struct list_head *list)
+{
+       struct list_head *node, *next;
+
+       BUG_ON(!spin_is_locked(&fctx->lock));
+
+       list_for_each_safe(node, next, &fctx->done) {
+               list_move_tail(node, list);
+       }
+}
+
+/*
+ * nouveau_fence_gc_free(list)
+ *
+ *     Unreference all of the fences in the list.
+ *
+ *     Caller MUST NOT hold the fences' channel's fence lock.
+ */
+static void
+nouveau_fence_gc_free(struct list_head *list)
+{
+       struct nouveau_fence *fence, *next;
+
+       list_for_each_entry_safe(fence, next, list, head) {
+               list_del(&fence->head);
+               nouveau_fence_unref(&fence);
+       }
+}
+
+/*
  * nouveau_fence_channel_release(channel)
  *
  *     Release the channel acquired with nouveau_fence_channel_acquire.
@@ -114,7 +151,8 @@
 /*
  * nouveau_fence_signal(fence)
  *
- *     Schedule all the work for fence's completion, and mark it done.
+ *     Schedule all the work for fence's completion, mark it done, and
+ *     move it from the pending list to the done list.
  *
  *     Caller must hold fence's channel's fence lock.
  */
@@ -136,7 +174,9 @@
 
        /* Note that the fence is done.  */
        fence->done = true;
-       list_del(&fence->head);
+
+       /* Move it from the pending list to the done list.  */
+       list_move_tail(&fence->head, &fctx->done);
 }
 
 static void
@@ -154,16 +194,22 @@
 nouveau_fence_context_del(struct nouveau_fence_chan *fctx)
 {
        struct nouveau_fence *fence, *fnext;
+       struct list_head done_list;
        int ret __diagused;
 
+       INIT_LIST_HEAD(&done_list);
+
        /* Signal all the fences in fctx.  */
        spin_lock(&fctx->lock);
        list_for_each_entry_safe(fence, fnext, &fctx->pending, head) {
                nouveau_fence_signal(fence);
-               /* XXX Doesn't this leak fence?  */
        }
+       nouveau_fence_gc_grab(fctx, &done_list);
        spin_unlock(&fctx->lock);
 
+       /* Release any fences that we signalled.  */
+       nouveau_fence_gc_free(&done_list);
+
        /* Wait for the workqueue to drain.  */
        flush_scheduled_work();
 
@@ -177,6 +223,11 @@
        BUG_ON(ret);
        spin_unlock(&fctx->lock);
 
+       /* Make sure there are no more fences on the list.  */
+       BUG_ON(!list_empty(&fctx->done));
+       BUG_ON(!list_empty(&fctx->flip));
+       BUG_ON(!list_empty(&fctx->pending));
+
        /* Destroy the fence context.  */
        DRM_DESTROY_WAITQUEUE(&fctx->waitqueue);
        spin_lock_destroy(&fctx->lock);
@@ -193,6 +244,7 @@
 
        INIT_LIST_HEAD(&fctx->flip);
        INIT_LIST_HEAD(&fctx->pending);
+       INIT_LIST_HEAD(&fctx->done);
        spin_lock_init(&fctx->lock);
        DRM_INIT_WAITQUEUE(&fctx->waitqueue, "nvfnchan");
        fctx->refcnt = 0;
@@ -275,7 +327,6 @@
                if (fctx->read(chan) < fence->sequence)
                        break;
                nouveau_fence_signal(fence);
-               nouveau_fence_unref(&fence);
        }
        BUG_ON(!spin_is_locked(&fctx->lock));
 }
@@ -349,18 +400,24 @@
 {
        struct nouveau_channel *chan;
        struct nouveau_fence_chan *fctx;
+       struct list_head done_list;
        bool done;
 
        if ((chan = nouveau_fence_channel_acquire(fence)) == NULL)
                return true;
 
+       INIT_LIST_HEAD(&done_list);
+
        fctx = chan->fence;
        spin_lock(&fctx->lock);
        done = nouveau_fence_done_locked(fence, chan);
+       nouveau_fence_gc_grab(fctx, &done_list);
        spin_unlock(&fctx->lock);
 
        nouveau_fence_channel_release(chan);
 
+       nouveau_fence_gc_free(&done_list);
+
        return done;
 }
 
@@ -397,6 +454,7 @@
        struct nouveau_fifo *pfifo = nouveau_fifo(chan->drm->device);
        struct nouveau_fence_chan *fctx = chan->fence;
        struct nouveau_eventh *handler;
+       struct list_head done_list;
        int ret = 0;
 
        BUG_ON(fence->channel != chan);
@@ -409,6 +467,8 @@
 
        nouveau_event_get(handler);
 
+       INIT_LIST_HEAD(&done_list);
+
        if (fence->timeout) {
                unsigned long timeout = fence->timeout - jiffies;
 
@@ -425,6 +485,7 @@
                                    timeout,
                                    nouveau_fence_done_locked(fence, chan));
                        }
+                       nouveau_fence_gc_grab(fctx, &done_list);
                        spin_unlock(&fctx->lock);
                }
 
@@ -444,10 +505,14 @@
                            &fctx->lock,
                            nouveau_fence_done_locked(fence, chan));
                }
+               nouveau_fence_gc_grab(fctx, &done_list);
                spin_unlock(&fctx->lock);
        }
 
        nouveau_event_ref(NULL, &handler);
+
+       nouveau_fence_gc_free(&done_list);
+
        if (unlikely(ret < 0))
                return ret;
 
diff -r b3527a88d652 -r 6fed98cf90d8 sys/external/bsd/drm2/dist/drm/nouveau/nouveau_fence.h
--- a/sys/external/bsd/drm2/dist/drm/nouveau/nouveau_fence.h    Thu Aug 23 01:10:04 2018 +0000
+++ b/sys/external/bsd/drm2/dist/drm/nouveau/nouveau_fence.h    Thu Aug 23 01:10:21 2018 +0000
@@ -36,6 +36,7 @@
 struct nouveau_fence_chan {
        struct list_head pending;
        struct list_head flip;
+       struct list_head done;
 
        int  (*emit)(struct nouveau_fence *);
        int  (*sync)(struct nouveau_fence *, struct nouveau_channel *,