gpu: nvgpu: add refcounting for TSG

Add refcounting for TSGs and manage the refcounts as below :
- initialize ref when TSG is opened
- get ref when channel is bound to TSG
- drop the ref when channel is unbound (i.e. during channel close)
- drop the ref when TSG is closed
- when refcount drops to zero, we free the TSG

This refcounting makes it possible to close channels or TSG
in any order

Bug 1470692

Change-Id: Ia4b39164a4582c8169da62a91b9131094c67f5f8
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/495667
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 15 insertions, 11 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/tsg_gk20a.c b/drivers/gpu/nvgpu/gk20a/tsg_gk20a.c
index 42d92f43..e7b70894 100644
--- a/drivers/gpu/nvgpu/gk20a/tsg_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/tsg_gk20a.c
@@ -24,6 +24,8 @@
 
 #include "gk20a.h"
 
+static void gk20a_tsg_release(struct kref *ref);
+
 bool gk20a_is_channel_marked_as_tsg(struct channel_gk20a *ch)
 {
         return !(ch->tsgid == NVGPU_INVALID_TSG_ID);
@@ -51,6 +53,8 @@ static int gk20a_tsg_bind_channel(struct tsg_gk20a *tsg, int ch_fd)
         list_add_tail(&ch->ch_entry, &tsg->ch_list);
         mutex_unlock(&tsg->ch_list_lock);
 
+        kref_get(&tsg->refcount);
+
         gk20a_dbg(gpu_dbg_fn, "BIND tsg:%d channel:%d\n",
                                         tsg->tsgid, ch->hw_chid);
 
@@ -68,6 +72,8 @@ int gk20a_tsg_unbind_channel(struct channel_gk20a *ch)
         list_del_init(&ch->ch_entry);
         mutex_unlock(&tsg->ch_list_lock);
 
+        kref_put(&tsg->refcount, gk20a_tsg_release);
+
         ch->tsgid = NVGPU_INVALID_TSG_ID;
 
         return 0;
@@ -134,6 +140,7 @@ int gk20a_tsg_dev_open(struct inode *inode, struct file *filp)
 
         tsg->g = g;
         tsg->num_active_channels = 0;
+        kref_init(&tsg->refcount);
 
         tsg->tsg_gr_ctx = NULL;
         tsg->vm = NULL;
@@ -145,18 +152,10 @@ int gk20a_tsg_dev_open(struct inode *inode, struct file *filp)
         return 0;
 }
 
-int gk20a_tsg_dev_release(struct inode *inode, struct file *filp)
+static void gk20a_tsg_release(struct kref *ref)
 {
-        struct tsg_gk20a *tsg = filp->private_data;
-        struct gk20a *g = container_of(inode->i_cdev,
-                         struct gk20a, tsg.cdev);
-
-        if (tsg->num_active_channels) {
-                gk20a_err(dev_from_gk20a(g),
-                        "Trying to free TSG %d with active channels %d\n",
-                        tsg->tsgid, tsg->num_active_channels);
-                return -EBUSY;
-        }
+        struct tsg_gk20a *tsg = container_of(ref, struct tsg_gk20a, refcount);
+        struct gk20a *g = tsg->g;
 
         if (tsg->tsg_gr_ctx) {
                 gr_gk20a_free_tsg_gr_ctx(tsg);
@@ -168,7 +167,12 @@ int gk20a_tsg_dev_release(struct inode *inode, struct file *filp)
         release_used_tsg(&g->fifo, tsg);
 
         gk20a_dbg(gpu_dbg_fn, "tsg released %d\n", tsg->tsgid);
+}
 
+int gk20a_tsg_dev_release(struct inode *inode, struct file *filp)
+{
+        struct tsg_gk20a *tsg = filp->private_data;
+        kref_put(&tsg->refcount, gk20a_tsg_release);
         return 0;
 }