kernel: Don't let things clear frames without holding the frame alloc lock

base/usr/include/kernel/mmu.h

@@ -23,6 +23,7 @@
 
 void mmu_frame_set(uintptr_t frame_addr);
 void mmu_frame_clear(uintptr_t frame_addr);
+void mmu_frame_release(uintptr_t frame_addr);
 int mmu_frame_test(uintptr_t frame_addr);
 uintptr_t mmu_first_n_frames(int n);
 uintptr_t mmu_first_frame(void);

kernel/arch/aarch64/mmu.c

@@ -129,6 +129,12 @@ static spin_lock_t kheap_lock = { 0 };
 static spin_lock_t mmio_space_lock = { 0 };
 static spin_lock_t module_space_lock = { 0 };
 
+void mmu_frame_release(uintptr_t frame_addr) {
+	spin_lock(frame_alloc_lock);
+	mmu_frame_clear(frame_addr);
+	spin_unlock(frame_alloc_lock);
+}
+
 uintptr_t mmu_first_n_frames(int n) {
 	for (uint64_t i = 0; i < nframes * PAGE_SIZE; i += PAGE_SIZE) {
 		int bad = 0;

kernel/arch/x86_64/mmu.c

@@ -121,6 +121,12 @@ static spin_lock_t kheap_lock = { 0 };
 static spin_lock_t mmio_space_lock = { 0 };
 static spin_lock_t module_space_lock = { 0 };
 
+void mmu_frame_release(uintptr_t frame_addr) {
+	spin_lock(frame_alloc_lock);
+	mmu_frame_clear(frame_addr);
+	spin_unlock(frame_alloc_lock);
+}
+
 /**
  * @brief Find the first range of @p n contiguous frames.
  *

kernel/misc/ringbuffer.c

@@ -175,7 +175,7 @@ ring_buffer_t * ring_buffer_create(size_t size) {
 
 void ring_buffer_destroy(ring_buffer_t * ring_buffer) {
 	if (ring_buffer->size == 4096) {
-		mmu_frame_clear((uintptr_t)ring_buffer->buffer & 0xFFFFFFFFF);
+		mmu_frame_release((uintptr_t)ring_buffer->buffer & 0xFFFFFFFFF);
 	} else {
 		free(ring_buffer->buffer);
 	}

kernel/sys/shm.c

@@ -131,7 +131,7 @@ static int release_chunk (shm_chunk_t * chunk) {
 
 			/* First, free the frames used by this chunk */
 			for (uint32_t i = 0; i < chunk->num_frames; i++) {
-				mmu_frame_clear(chunk->frames[i] << 12);
+				mmu_frame_release(chunk->frames[i] << 12);
 			}
 
 			/* Then, get rid of the damn thing */

kernel/vfs/ramdisk.c

@@ -82,7 +82,7 @@ static int ioctl_ramdisk(fs_node_t * node, unsigned long request, void * argp) {
 						node->length -= node->length % 0x1000;
 					}
 					for (uintptr_t i = node->inode; i < (node->inode + node->length); i += 0x1000) {
-						mmu_frame_clear(i);
+						mmu_frame_release(i);
 					}
 				}
 				/* Mark the file length as 0 */

kernel/vfs/tmpfs.c

@@ -131,7 +131,7 @@ static void tmpfs_file_free(struct tmpfs_file * t) {
 	}
 	spin_lock(t->lock);
 	for (size_t i = 0; i < t->block_count; ++i) {
-		mmu_frame_clear((uintptr_t)t->blocks[i] * 0x1000);
+		mmu_frame_release((uintptr_t)t->blocks[i] * 0x1000);
 		tmpfs_total_blocks--;
 	}
 	spin_unlock(t->lock);
@@ -277,7 +277,7 @@ static int truncate_tmpfs(fs_node_t * node) {
 	struct tmpfs_file * t = (struct tmpfs_file *)(node->device);
 	spin_lock(t->lock);
 	for (size_t i = 0; i < t->block_count; ++i) {
-		mmu_frame_clear((uintptr_t)t->blocks[i] * 0x1000);
+		mmu_frame_release((uintptr_t)t->blocks[i] * 0x1000);
 		tmpfs_total_blocks--;
 		t->blocks[i] = 0;
 	}