Add memory usage accounting to avoid DOS problems.

1 files changed, 69 insertions, 0 deletions

diff --git a/linux-core/drm_memory.c b/linux-core/drm_memory.c
index 9125cd47..ba65136a 100644
--- a/linux-core/drm_memory.c
+++ b/linux-core/drm_memory.c
@@ -37,6 +37,75 @@
 #include <linux/highmem.h>
 #include "drmP.h"
 
+static struct {
+	spinlock_t lock;
+	drm_u64_t cur_used;
+	drm_u64_t low_threshold;
+	drm_u64_t high_threshold;
+} drm_memctl = {
+	.lock = SPIN_LOCK_UNLOCKED
+};
+
+static inline size_t drm_size_align(size_t size) {
+
+	register size_t tmpSize = 4;
+	if (size > PAGE_SIZE)
+		return PAGE_ALIGN(size);
+
+	while(tmpSize < size)
+		tmpSize <<= 1;
+
+	return (size_t) tmpSize;
+}
+
+int drm_alloc_memctl(size_t size)
+{
+	int ret;
+	unsigned long a_size = drm_size_align(size);
+ 
+	spin_lock(&drm_memctl.lock);
+	ret = ((drm_memctl.cur_used + a_size) > drm_memctl.high_threshold) ? 
+		-ENOMEM : 0;
+	if (!ret) 
+		drm_memctl.cur_used += a_size;
+	spin_unlock(&drm_memctl.lock);
+	return ret;
+}
+EXPORT_SYMBOL(drm_alloc_memctl);
+	
+void drm_free_memctl(size_t size)
+{
+	unsigned long a_size = drm_size_align(size);
+
+	spin_lock(&drm_memctl.lock);
+	drm_memctl.cur_used -= a_size;
+	spin_unlock(&drm_memctl.lock);
+}
+EXPORT_SYMBOL(drm_free_memctl);
+
+void drm_query_memctl(drm_u64_t *cur_used,
+		      drm_u64_t *low_threshold,
+		      drm_u64_t *high_threshold) 
+{
+	spin_lock(&drm_memctl.lock);
+	*cur_used = drm_memctl.cur_used;
+	*low_threshold = drm_memctl.low_threshold;
+	*high_threshold = drm_memctl.high_threshold;
+	spin_unlock(&drm_memctl.lock);
+}	
+EXPORT_SYMBOL(drm_query_memctl);
+
+void drm_init_memctl(size_t p_low_threshold,
+		     size_t p_high_threshold)
+{
+	spin_lock(&drm_memctl.lock);
+	drm_memctl.cur_used = 0;
+	drm_memctl.low_threshold = p_low_threshold << PAGE_SHIFT;
+	drm_memctl.high_threshold = p_high_threshold << PAGE_SHIFT;
+	spin_unlock(&drm_memctl.lock);
+}
+
+
 #ifndef DEBUG_MEMORY
 
 /** No-op. */