video: tegra: host: revise channel refcnt API's

Use only one API to subtract channel refcnts.
To check unbanalaced channel refcnt add WARN_ON when count
goes below zero.
Print error number when channel unmap fails.

Bug 1526504

Change-Id: If88f028a44c9b796d8eaae4affcd0026758cfbe8
(cherry picked from commit f98ce1fc2066e2309af2ef7a52801abadbd40f00)
Signed-off-by: Shridhar Rasal <srasal@nvidia.com>
Reviewed-on: http://git-master/r/496479
Reviewed-on: http://git-master/r/538723
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Shreshtha Sahu <ssahu@nvidia.com>
Tested-by: Shreshtha Sahu <ssahu@nvidia.com>
Reviewed-by: Venkat Moganty <vmoganty@nvidia.com>

5 files changed, 18 insertions, 20 deletions

diff --git a/drivers/video/tegra/host/bus_client.c b/drivers/video/tegra/host/bus_client.c
index 819f0cee59c8..634384329992 100644
--- a/drivers/video/tegra/host/bus_client.c
+++ b/drivers/video/tegra/host/bus_client.c
@@ -202,7 +202,7 @@ static int nvhost_channelrelease(struct inode *inode, struct file *filp)
 		nvhost_job_put(priv->job);
 
 	mutex_unlock(&channel_lock);
-	nvhost_putchannel(priv->ch);
+	nvhost_putchannel(priv->ch, 1);
 	kfree(priv);
 	return 0;
 }
@@ -220,7 +220,8 @@ static int __nvhost_channelopen(struct inode *inode,
 				struct nvhost_device_data, cdev);
 		ret = nvhost_channel_map(pdata, &ch);
 		if (ret) {
-			pr_err("%s: failed to map channel\n", __func__);
+			pr_err("%s: failed to map channel, error: %d\n",
+					__func__, ret);
 			return ret;
 		}
 	} else {
@@ -244,7 +245,7 @@ static int __nvhost_channelopen(struct inode *inode,
 
 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 	if (!priv) {
-		nvhost_putchannel(ch);
+		nvhost_putchannel(ch, 1);
 		goto fail;
 	}
 	filp->private_data = priv;
diff --git a/drivers/video/tegra/host/host1x/host1x_channel.c b/drivers/video/tegra/host/host1x/host1x_channel.c
index 46f319ea83f6..5b2b4998af92 100644
--- a/drivers/video/tegra/host/host1x/host1x_channel.c
+++ b/drivers/video/tegra/host/host1x/host1x_channel.c
@@ -318,7 +318,7 @@ static int host1x_channel_submit(struct nvhost_job *job)
 	err = mutex_lock_interruptible(&ch->submitlock);
 	if (err) {
 		nvhost_module_idle_mult(ch->dev, job->num_syncpts);
-		nvhost_putchannel_mult(ch, job->num_syncpts);
+		nvhost_putchannel(ch, job->num_syncpts);
 		goto error;
 	}
 
@@ -326,7 +326,7 @@ static int host1x_channel_submit(struct nvhost_job *job)
 		completed_waiters[i] = nvhost_intr_alloc_waiter();
 		if (!completed_waiters[i]) {
 			nvhost_module_idle_mult(ch->dev, job->num_syncpts);
-			nvhost_putchannel_mult(ch, job->num_syncpts);
+			nvhost_putchannel(ch, job->num_syncpts);
 			mutex_unlock(&ch->submitlock);
 			err = -ENOMEM;
 			goto error;
@@ -342,7 +342,7 @@ static int host1x_channel_submit(struct nvhost_job *job)
 	err = nvhost_cdma_begin(&ch->cdma, job);
 	if (err) {
 		nvhost_module_idle_mult(ch->dev, job->num_syncpts);
-		nvhost_putchannel_mult(ch, job->num_syncpts);
+		nvhost_putchannel(ch, job->num_syncpts);
 		mutex_unlock(&ch->submitlock);
 		goto error;
 	}
diff --git a/drivers/video/tegra/host/nvhost_channel.c b/drivers/video/tegra/host/nvhost_channel.c
index 3e7455509f96..9f0ca9e1268e 100644
--- a/drivers/video/tegra/host/nvhost_channel.c
+++ b/drivers/video/tegra/host/nvhost_channel.c
@@ -125,7 +125,7 @@ int nvhost_channel_release(struct nvhost_device_data *pdata)
 	for (i = 0; i < pdata->num_channels; i++) {
 		ch = pdata->channels[i];
 		if (ch && ch->dev)
-			nvhost_putchannel(ch);
+			nvhost_putchannel(ch, 1);
 	}
 	return 0;
 }
@@ -377,19 +377,17 @@ void nvhost_getchannel(struct nvhost_channel *ch)
 	atomic_inc(&ch->refcount);
 }
 
-void nvhost_putchannel(struct nvhost_channel *ch)
+void nvhost_putchannel(struct nvhost_channel *ch, int cnt)
 {
-	if (!atomic_dec_if_positive(&ch->refcount))
-		nvhost_channel_unmap(ch);
-}
-
+	int ref;
 
-void nvhost_putchannel_mult(struct nvhost_channel *ch, int cnt)
-{
-	int i;
+	ref = atomic_sub_return(cnt, &ch->refcount);
 
-	for (i = 0; i < cnt; i++)
-		nvhost_putchannel(ch);
+	/* WARN on negative reference, with zero reference unmap channel*/
+	if (!ref)
+		nvhost_channel_unmap(ch);
+	else if (ref < 0)
+		WARN_ON(1);
 }
 
 int nvhost_channel_suspend(struct nvhost_channel *ch)
diff --git a/drivers/video/tegra/host/nvhost_channel.h b/drivers/video/tegra/host/nvhost_channel.h
index 9f165a380f4a..84643a28aca8 100644
--- a/drivers/video/tegra/host/nvhost_channel.h
+++ b/drivers/video/tegra/host/nvhost_channel.h
@@ -85,8 +85,7 @@ void nvhost_set_notifier(struct nvhost_channel *ch, __u32 error);
 void nvhost_free_error_notifiers(struct nvhost_channel *ch);
 
 void nvhost_getchannel(struct nvhost_channel *ch);
-void nvhost_putchannel(struct nvhost_channel *ch);
-void nvhost_putchannel_mult(struct nvhost_channel *ch, int cnt);
+void nvhost_putchannel(struct nvhost_channel *ch, int cnt);
 int nvhost_channel_suspend(struct nvhost_channel *ch);
 
 int nvhost_channel_read_reg(struct nvhost_channel *channel,
diff --git a/drivers/video/tegra/host/nvhost_intr.c b/drivers/video/tegra/host/nvhost_intr.c
index 18b714c7e482..b856f26cb5f8 100644
--- a/drivers/video/tegra/host/nvhost_intr.c
+++ b/drivers/video/tegra/host/nvhost_intr.c
@@ -175,7 +175,7 @@ static void action_submit_complete(struct nvhost_waitlist *waiter)
 			channel->cdma.med_prio_count,
 			channel->cdma.low_prio_count);
 
-	nvhost_putchannel_mult(channel, nr_completed);
+	nvhost_putchannel(channel, nr_completed);
 
 }