[PATCH 03/31] staging: bcm2835-camera: Replace spinlock protecting context_map with mutex

[Stefan Wahren]

From: Dave Stevenson <dave.steven...@raspberrypi.org>

The commit "staging: bcm2835-camera: Replace open-coded idr with a struct idr."
replaced an internal implementation of an idr with the standard functions
and a spinlock. idr_alloc(GFP_KERNEL) can sleep whilst calling kmem_cache_alloc
to allocate the new node, but this is not valid whilst in an atomic context
due to the spinlock.

There is no need for this to be a spinlock as a standard mutex is
sufficient.

Fixes: 950fd867c635 ("staging: bcm2835-camera: Replace open-coded idr with a 
struct idr.")
Signed-off-by: Dave Stevenson <dave.steven...@raspberrypi.org>
---
 drivers/staging/vc04_services/bcm2835-camera/mmal-vchiq.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/vc04_services/bcm2835-camera/mmal-vchiq.c 
b/drivers/staging/vc04_services/bcm2835-camera/mmal-vchiq.c
index 16af735..f1bb900 100644
--- a/drivers/staging/vc04_services/bcm2835-camera/mmal-vchiq.c
+++ b/drivers/staging/vc04_services/bcm2835-camera/mmal-vchiq.c
@@ -161,7 +161,8 @@ struct vchiq_mmal_instance {
        void *bulk_scratch;

        struct idr context_map;
-       spinlock_t context_map_lock;
+       /* protect accesses to context_map */
+       struct mutex context_map_lock;

        /* component to use next */
        int component_idx;
@@ -184,10 +185,10 @@ get_msg_context(struct vchiq_mmal_instance *instance)
         * that when we service the VCHI reply, we can look up what
         * message is being replied to.
         */
-       spin_lock(&instance->context_map_lock);
+       mutex_lock(&instance->context_map_lock);
        handle = idr_alloc(&instance->context_map, msg_context,
                           0, 0, GFP_KERNEL);
-       spin_unlock(&instance->context_map_lock);
+       mutex_unlock(&instance->context_map_lock);

        if (handle < 0) {
                kfree(msg_context);
@@ -211,9 +212,9 @@ release_msg_context(struct mmal_msg_context *msg_context)
 {
        struct vchiq_mmal_instance *instance = msg_context->instance;

-       spin_lock(&instance->context_map_lock);
+       mutex_lock(&instance->context_map_lock);
        idr_remove(&instance->context_map, msg_context->handle);
-       spin_unlock(&instance->context_map_lock);
+       mutex_unlock(&instance->context_map_lock);
        kfree(msg_context);
 }

@@ -1849,7 +1850,7 @@ int vchiq_mmal_init(struct vchiq_mmal_instance 
**out_instance)

        instance->bulk_scratch = vmalloc(PAGE_SIZE);

-       spin_lock_init(&instance->context_map_lock);
+       mutex_init(&instance->context_map_lock);
        idr_init_base(&instance->context_map, 1);

        params.callback_param = instance;
--
2.7.4