[PATCH 1/3] gpu: host1x: Add locking in channel allocation

[Mikko Perttunen]

From: Mikko Perttunen <mperttu...@nvidia.com>

Add locking around channel allocation to avoid race conditions.

Signed-off-by: Mikko Perttunen <mperttu...@nvidia.com>
---
 drivers/gpu/host1x/channel.c | 7 +++++++
 drivers/gpu/host1x/channel.h | 3 +++
 2 files changed, 10 insertions(+)

diff --git a/drivers/gpu/host1x/channel.c b/drivers/gpu/host1x/channel.c
index 2d0051d6314c..79501c957532 100644
--- a/drivers/gpu/host1x/channel.c
+++ b/drivers/gpu/host1x/channel.c
@@ -27,6 +27,8 @@ int host1x_channel_list_init(struct host1x_channel_list 
*chlist,
                return -ENOMEM;
        }
 
+       mutex_init(&chlist->lock);
+
        return 0;
 }
 
@@ -104,8 +106,11 @@ static struct host1x_channel 
*acquire_unused_channel(struct host1x *host)
        unsigned int max_channels = host->info->nb_channels;
        unsigned int index;
 
+       mutex_lock(&chlist->lock);
+
        index = find_first_zero_bit(chlist->allocated_channels, max_channels);
        if (index >= max_channels) {
+               mutex_unlock(&chlist->lock);
                dev_err(host->dev, "failed to find free channel\n");
                return NULL;
        }
@@ -114,6 +119,8 @@ static struct host1x_channel *acquire_unused_channel(struct 
host1x *host)
 
        set_bit(index, chlist->allocated_channels);
 
+       mutex_unlock(&chlist->lock);
+
        return &chlist->channels[index];
 }
 
diff --git a/drivers/gpu/host1x/channel.h b/drivers/gpu/host1x/channel.h
index 39044ff6c3aa..b23a8071fbd0 100644
--- a/drivers/gpu/host1x/channel.h
+++ b/drivers/gpu/host1x/channel.h
@@ -10,6 +10,7 @@
 
 #include <linux/io.h>
 #include <linux/kref.h>
+#include <linux/mutex.h>
 
 #include "cdma.h"
 
@@ -18,6 +19,8 @@ struct host1x_channel;
 
 struct host1x_channel_list {
        struct host1x_channel *channels;
+
+       struct mutex lock;
        unsigned long *allocated_channels;
 };
 
-- 
2.41.0