From 16a229c9360e205a70f5ceef148cf65d15d77363 Mon Sep 17 00:00:00 2001
From: fef <owo@fef.moe>
Date: Sat, 23 Oct 2021 02:50:04 +0200
Subject: [PATCH] mm: protect cache pools with mutex

---
 include/gay/mutex.h | 10 +++++-----
 kernel/mm/page.c    | 18 +++++++++++++++++-
 2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/include/gay/mutex.h b/include/gay/mutex.h
index 1a3e383..8ccabde 100644
--- a/include/gay/mutex.h
+++ b/include/gay/mutex.h
@@ -11,10 +11,12 @@ typedef struct {
 	atom_t lock;
 } spin_t;
 
-#define SPIN(name) struct spin name = {	\
+#define SPIN_DEFINE {			\
 	.lock = ATOM_DEFINE(0),		\
 }
 
+#define SPIN(name) struct spin name = SPIN_DEFINE
+
 void spin_init(spin_t *spin);
 void spin_lock(spin_t *spin);
 int spin_trylock(spin_t *spin);
@@ -33,10 +35,8 @@ struct mtx {
 
 #define MTX_DEFINE(name) {					\
 	.lock = ATOM_DEFINE(0),					\
-	.wait_queue_lock = {					\
-		.lock = ATOM_DEFINE(0)				\
-	},							\
-	.wait_queue = CLIST_DEFINE(&(name).wait_queue),		\
+	.wait_queue_lock = SPIN_DEFINE,				\
+	.wait_queue = CLIST_DEFINE((name).wait_queue),		\
 }
 
 #define MTX(name) struct mtx name = MTX_DEFINE(name)
diff --git a/kernel/mm/page.c b/kernel/mm/page.c
index 8d18e43..e83190b 100644
--- a/kernel/mm/page.c
+++ b/kernel/mm/page.c
@@ -7,6 +7,7 @@
 #include <gay/config.h>
 #include <gay/kprintf.h>
 #include <gay/mm.h>
+#include <gay/mutex.h>
 #include <gay/types.h>
 #include <gay/util.h>
 
@@ -62,6 +63,7 @@ struct cache_pool {
 	usize free_entries;
 };
 static struct cache_pool caches[CACHE_LEVELS];
+MTX(caches_lock);
 
 #define LONG_BIT_MASK (~(LONG_BIT - 1))
 
@@ -220,6 +222,12 @@ void *get_pages(usize count, enum mm_flags flags)
 		return nil;
 	}
 
+	if (flags & MM_NOSLEEP) {
+		kprintf("get_pages(): MM_NOSLEEP requested, this is not implemented yet :(\n");
+		return nil;
+	}
+	mtx_lock(&caches_lock);
+
 	struct clist *entry;
 	int entry_level;
 	for (entry_level = level; entry_level < CACHE_LEVELS; entry_level++) {
@@ -228,8 +236,10 @@ void *get_pages(usize count, enum mm_flags flags)
 			break;
 		}
 	}
-	if (entry_level == CACHE_LEVELS)
+	if (entry_level == CACHE_LEVELS) {
+		mtx_unlock(&caches_lock);
 		return nil;
+	}
 
 	clist_del(entry);
 	caches[entry_level].free_entries--;
@@ -243,6 +253,7 @@ void *get_pages(usize count, enum mm_flags flags)
 	}
 	bit_set(caches[level].bitmap, bit_number);
 
+	mtx_unlock(&caches_lock);
 	return (void *)entry;
 }
 
@@ -254,11 +265,14 @@ void free_pages(void *ptr, usize count)
 		return;
 	}
 
+	mtx_lock(&caches_lock);
+
 	usize bit_number = get_bit_number(ptr, level);
 
 #	if CFG_DEBUG_PAGE_ALLOCS
 		if (!bit_tst(caches[level].bitmap, bit_number)) {
 			kprintf("free_pages(%p, %zu): double free!\n", ptr, count);
+			mtx_unlock(&caches_lock);
 			return;
 		}
 #	endif
@@ -273,6 +287,8 @@ void free_pages(void *ptr, usize count)
 		level++;
 		bit_number >>= 1;
 	}
+
+	mtx_unlock(&caches_lock);
 }
 
 static inline usize get_bit_number(void *ptr, int level)