gpu: nvgpu: Free the channel used semaphore index

Free the channel used semaphore index during gk20a_free_channel().

Bug 1793819

Change-Id: I4215d05f7f3ba0636e2abb1803011711c8a38301
Signed-off-by: Lakshmanan M <lm@nvidia.com>
Reviewed-on: http://git-master/r/1196877
(cherry picked from commit 2c5720de506caac29629f6a1c578e6da80b1a135)
Reviewed-on: http://git-master/r/1198883
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

3 files changed, 29 insertions, 6 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
index 85b77199..eae2bdae 100644
--- a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
@@ -978,6 +978,10 @@ unbind:
         g->ops.fifo.unbind_channel(ch);
         g->ops.fifo.free_inst(g, ch);
 
+        /* free the channel used semaphore index */
+        if (ch->hw_sema)
+                gk20a_semaphore_free_hw_sema(ch);
+
         ch->vpr = false;
         ch->vm = NULL;
 
@@ -1006,9 +1010,6 @@ unbind:
 
         mutex_unlock(&g->dbg_sessions_lock);
 
-        /* Make sure that when the ch is re-opened it will get a new HW sema. */
-        ch->hw_sema = NULL;
-
         /* make sure we catch accesses of unopened channels in case
          * there's non-refcounted channel pointers hanging around */
         ch->g = NULL;
diff --git a/drivers/gpu/nvgpu/gk20a/semaphore_gk20a.c b/drivers/gpu/nvgpu/gk20a/semaphore_gk20a.c
index d513fa84..396e7419 100644
--- a/drivers/gpu/nvgpu/gk20a/semaphore_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/semaphore_gk20a.c
@@ -3,7 +3,7 @@
  *
  * GK20A Semaphores
  *
- * Copyright (c) 2014-2015, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2014-2016, NVIDIA CORPORATION.  All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -364,6 +364,27 @@ fail:
 }
 
 /*
+ * Free the channel used semaphore index
+ */
+void gk20a_semaphore_free_hw_sema(struct channel_gk20a *ch)
+{
+        struct gk20a_semaphore_pool *p = ch->vm->sema_pool;
+
+        BUG_ON(!p);
+
+        mutex_lock(&p->pool_lock);
+
+        clear_bit(ch->hw_sema->idx, p->semas_alloced);
+
+        /* Make sure that when the ch is re-opened it will get a new HW sema. */
+        list_del(&ch->hw_sema->hw_sema_list);
+        kfree(ch->hw_sema);
+        ch->hw_sema = NULL;
+
+        mutex_unlock(&p->pool_lock);
+}
+
+/*
  * Allocate a semaphore from the passed pool.
  *
  * Since semaphores are ref-counted there's no explicit free for external code
@@ -377,7 +398,7 @@ struct gk20a_semaphore *gk20a_semaphore_alloc(struct channel_gk20a *ch)
         if (!ch->hw_sema) {
                 ret = __gk20a_init_hw_sema(ch);
                 if (ret)
-                        return ERR_PTR(ret);
+                        return NULL;
         }
 
         s = kzalloc(sizeof(*s), GFP_KERNEL);
diff --git a/drivers/gpu/nvgpu/gk20a/semaphore_gk20a.h b/drivers/gpu/nvgpu/gk20a/semaphore_gk20a.h
index 58081b56..29a01ab8 100644
--- a/drivers/gpu/nvgpu/gk20a/semaphore_gk20a.h
+++ b/drivers/gpu/nvgpu/gk20a/semaphore_gk20a.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, NVIDIA CORPORATION.  All rights reserved.
+ * Copyright (c) 2014-2016, NVIDIA CORPORATION.  All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -174,6 +174,7 @@ void gk20a_semaphore_pool_put(struct gk20a_semaphore_pool *p);
 struct gk20a_semaphore *gk20a_semaphore_alloc(struct channel_gk20a *ch);
 void gk20a_semaphore_put(struct gk20a_semaphore *s);
 void gk20a_semaphore_get(struct gk20a_semaphore *s);
+void gk20a_semaphore_free_hw_sema(struct channel_gk20a *ch);
 
 /*
  * Return the address of a specific semaphore.