[PATCH 2/4] gpu: host1x: Add locking to syncpt

[Mikko Perttunen]

From: Arto Merilainen <amerilai...@nvidia.com>

Currently syncpoints are not locked by mutex and this causes races
if we are aggressively freeing and allocating syncpoints.

This patch adds missing mutex protection to syncpoint structures.

Signed-off-by: Arto Merilainen <amerilainen at nvidia.com>
Reviewed-by: Shridhar Rasal <srasal at nvidia.com>
Signed-off-by: Mikko Perttunen <mperttunen at nvidia.com>
---
 drivers/gpu/host1x/dev.h    |  3 ++-
 drivers/gpu/host1x/syncpt.c | 25 +++++++++++++++++++++----
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/host1x/dev.h b/drivers/gpu/host1x/dev.h
index 5220510..06dd4f8 100644
--- a/drivers/gpu/host1x/dev.h
+++ b/drivers/gpu/host1x/dev.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012-2013, NVIDIA Corporation.
+ * Copyright (c) 2012-2015, NVIDIA Corporation.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -120,6 +120,7 @@ struct host1x {

        struct host1x_syncpt *nop_sp;

+       struct mutex syncpt_mutex;
        struct mutex chlist_mutex;
        struct host1x_channel chlist;
        unsigned long allocated_channels;
diff --git a/drivers/gpu/host1x/syncpt.c b/drivers/gpu/host1x/syncpt.c
index 9558932..f3b04ed 100644
--- a/drivers/gpu/host1x/syncpt.c
+++ b/drivers/gpu/host1x/syncpt.c
@@ -1,7 +1,7 @@
 /*
  * Tegra host1x Syncpoints
  *
- * Copyright (c) 2010-2013, NVIDIA Corporation.
+ * Copyright (c) 2010-2015, NVIDIA Corporation.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -61,22 +61,24 @@ static struct host1x_syncpt *host1x_syncpt_alloc(struct 
host1x *host,
        struct host1x_syncpt *sp = host->syncpt;
        char *name;

+       mutex_lock(&host->syncpt_mutex);
+
        for (i = 0; i < host->info->nb_pts && sp->name; i++, sp++)
                ;

        if (i >= host->info->nb_pts)
-               return NULL;
+               goto err_alloc_syncpt;

        if (flags & HOST1X_SYNCPT_HAS_BASE) {
                sp->base = host1x_syncpt_base_request(host);
                if (!sp->base)
-                       return NULL;
+                       goto err_alloc_base;
        }

        name = kasprintf(GFP_KERNEL, "%02u-%s", sp->id,
                        dev ? dev_name(dev) : NULL);
        if (!name)
-               return NULL;
+               goto err_alloc_name;

        sp->dev = dev;
        sp->name = name;
@@ -86,7 +88,17 @@ static struct host1x_syncpt *host1x_syncpt_alloc(struct 
host1x *host,
        else
                sp->client_managed = false;

+       mutex_unlock(&host->syncpt_mutex);
        return sp;
+
+err_alloc_name:
+       host1x_syncpt_base_free(sp->base);
+       sp->base = NULL;
+err_alloc_base:
+       sp = NULL;
+err_alloc_syncpt:
+       mutex_unlock(&host->syncpt_mutex);
+       return NULL;
 }

 u32 host1x_syncpt_id(struct host1x_syncpt *sp)
@@ -378,6 +390,7 @@ int host1x_syncpt_init(struct host1x *host)
        for (i = 0; i < host->info->nb_bases; i++)
                bases[i].id = i;

+       mutex_init(&host->syncpt_mutex);
        host->syncpt = syncpt;
        host->bases = bases;

@@ -405,12 +418,16 @@ void host1x_syncpt_free(struct host1x_syncpt *sp)
        if (!sp)
                return;

+       mutex_lock(&sp->host->syncpt_mutex);
+
        host1x_syncpt_base_free(sp->base);
        kfree(sp->name);
        sp->base = NULL;
        sp->dev = NULL;
        sp->name = NULL;
        sp->client_managed = false;
+
+       mutex_unlock(&sp->host->syncpt_mutex);
 }
 EXPORT_SYMBOL(host1x_syncpt_free);

-- 
2.9.3