[media] staging: atomisp: Fix endless recursion in hmm_init

hmm_init calls hmm_alloc to set dummy_ptr, hmm_alloc calls
hmm_init when dummy_ptr is not yet set, which is the case in
the call from hmm_init, so it calls hmm_init again, this continues
until we have a stack overflow due to the recursion.

This commit fixes this by adding a separate flag for tracking if
hmm_init has been called. Not pretty, but it gets the job done,
eventually we should be able to remove the hmm_init call from
hmm_alloc.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/staging/media/atomisp/pci/atomisp2/hmm/hmm.c

@@ -43,6 +43,7 @@ struct hmm_bo_device bo_device;
 struct hmm_pool	dynamic_pool;
 struct hmm_pool	reserved_pool;
 static ia_css_ptr dummy_ptr;
+static bool hmm_initialized;
 struct _hmm_mem_stat hmm_mem_stat;
 
 /* p: private
@@ -186,6 +187,8 @@ int hmm_init(void)
 	if (ret)
 		dev_err(atomisp_dev, "hmm_bo_device_init failed.\n");
 
+	hmm_initialized = true;
+
 	/*
 	 * As hmm use NULL to indicate invalid ISP virtual address,
 	 * and ISP_VM_START is defined to 0 too, so we allocate
@@ -217,6 +220,7 @@ void hmm_cleanup(void)
 	dummy_ptr = 0;
 
 	hmm_bo_device_exit(&bo_device);
+	hmm_initialized = false;
 }
 
 ia_css_ptr hmm_alloc(size_t bytes, enum hmm_bo_type type,
@@ -229,7 +233,7 @@ ia_css_ptr hmm_alloc(size_t bytes, enum hmm_bo_type type,
 	/* Check if we are initialized. In the ideal world we wouldn't need
 	   this but we can tackle it once the driver is a lot cleaner */
 
-	if (!dummy_ptr)
+	if (!hmm_initialized)
 		hmm_init();
 	/*Get page number from size*/
 	pgnr = size_to_pgnr_ceil(bytes);