1 files changed, 70 insertions, 22 deletions

diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index 59337326e28..34a1e5aa848 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -12,6 +12,8 @@
  *
  */
 
+#define pr_fmt(fmt) "persistent_ram: " fmt
+
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/errno.h>
@@ -46,7 +48,7 @@ static inline size_t buffer_start(struct persistent_ram_zone *prz)
 }
 
 /* increase and wrap the start pointer, returning the old value */
-static inline size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
+static size_t buffer_start_add_atomic(struct persistent_ram_zone *prz, size_t a)
 {
 	int old;
 	int new;
@@ -54,7 +56,7 @@ static inline size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
 	do {
 		old = atomic_read(&prz->buffer->start);
 		new = old + a;
-		while (unlikely(new > prz->buffer_size))
+		while (unlikely(new >= prz->buffer_size))
 			new -= prz->buffer_size;
 	} while (atomic_cmpxchg(&prz->buffer->start, old, new) != old);
 
@@ -62,7 +64,7 @@ static inline size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
 }
 
 /* increase the size counter until it hits the max size */
-static inline void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
+static void buffer_size_add_atomic(struct persistent_ram_zone *prz, size_t a)
 {
 	size_t old;
 	size_t new;
@@ -78,6 +80,53 @@ static inline void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
 	} while (atomic_cmpxchg(&prz->buffer->size, old, new) != old);
 }
 
+static DEFINE_RAW_SPINLOCK(buffer_lock);
+
+/* increase and wrap the start pointer, returning the old value */
+static size_t buffer_start_add_locked(struct persistent_ram_zone *prz, size_t a)
+{
+	int old;
+	int new;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&buffer_lock, flags);
+
+	old = atomic_read(&prz->buffer->start);
+	new = old + a;
+	while (unlikely(new >= prz->buffer_size))
+		new -= prz->buffer_size;
+	atomic_set(&prz->buffer->start, new);
+
+	raw_spin_unlock_irqrestore(&buffer_lock, flags);
+
+	return old;
+}
+
+/* increase the size counter until it hits the max size */
+static void buffer_size_add_locked(struct persistent_ram_zone *prz, size_t a)
+{
+	size_t old;
+	size_t new;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&buffer_lock, flags);
+
+	old = atomic_read(&prz->buffer->size);
+	if (old == prz->buffer_size)
+		goto exit;
+
+	new = old + a;
+	if (new > prz->buffer_size)
+		new = prz->buffer_size;
+	atomic_set(&prz->buffer->size, new);
+
+exit:
+	raw_spin_unlock_irqrestore(&buffer_lock, flags);
+}
+
+static size_t (*buffer_start_add)(struct persistent_ram_zone *, size_t) = buffer_start_add_atomic;
+static void (*buffer_size_add)(struct persistent_ram_zone *, size_t) = buffer_size_add_atomic;
+
 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
 	uint8_t *data, size_t len, uint8_t *ecc)
 {
@@ -158,12 +207,10 @@ static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
 			size = buffer->data + prz->buffer_size - block;
 		numerr = persistent_ram_decode_rs8(prz, block, size, par);
 		if (numerr > 0) {
-			pr_devel("persistent_ram: error in block %p, %d\n",
-			       block, numerr);
+			pr_devel("error in block %p, %d\n", block, numerr);
 			prz->corrected_bytes += numerr;
 		} else if (numerr < 0) {
-			pr_devel("persistent_ram: uncorrectable error in block %p\n",
-				block);
+			pr_devel("uncorrectable error in block %p\n", block);
 			prz->bad_blocks++;
 		}
 		block += prz->ecc_info.block_size;
@@ -210,7 +257,7 @@ static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
 	prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
 				  0, 1, prz->ecc_info.ecc_size);
 	if (prz->rs_decoder == NULL) {
-		pr_info("persistent_ram: init_rs failed\n");
+		pr_info("init_rs failed\n");
 		return -EINVAL;
 	}
 
@@ -220,10 +267,10 @@ static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
 	numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
 					   prz->par_header);
 	if (numerr > 0) {
-		pr_info("persistent_ram: error in header, %d\n", numerr);
+		pr_info("error in header, %d\n", numerr);
 		prz->corrected_bytes += numerr;
 	} else if (numerr < 0) {
-		pr_info("persistent_ram: uncorrectable error in header\n");
+		pr_info("uncorrectable error in header\n");
 		prz->bad_blocks++;
 	}
 
@@ -270,7 +317,7 @@ void persistent_ram_save_old(struct persistent_ram_zone *prz)
 		prz->old_log = kmalloc(size, GFP_KERNEL);
 	}
 	if (!prz->old_log) {
-		pr_err("persistent_ram: failed to allocate buffer\n");
+		pr_err("failed to allocate buffer\n");
 		return;
 	}
 
@@ -349,8 +396,8 @@ static void *persistent_ram_vmap(phys_addr_t start, size_t size)
 
 	pages = kmalloc(sizeof(struct page *) * page_count, GFP_KERNEL);
 	if (!pages) {
-		pr_err("%s: Failed to allocate array for %u pages\n", __func__,
-			page_count);
+		pr_err("%s: Failed to allocate array for %u pages\n",
+		       __func__, page_count);
 		return NULL;
 	}
 
@@ -372,6 +419,9 @@ static void *persistent_ram_iomap(phys_addr_t start, size_t size)
 		return NULL;
 	}
 
+	buffer_start_add = buffer_start_add_locked;
+	buffer_size_add = buffer_size_add_locked;
+
 	return ioremap(start, size);
 }
 
@@ -412,19 +462,17 @@ static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
 	if (prz->buffer->sig == sig) {
 		if (buffer_size(prz) > prz->buffer_size ||
 		    buffer_start(prz) > buffer_size(prz))
-			pr_info("persistent_ram: found existing invalid buffer,"
-				" size %zu, start %zu\n",
-			       buffer_size(prz), buffer_start(prz));
+			pr_info("found existing invalid buffer, size %zu, start %zu\n",
+				buffer_size(prz), buffer_start(prz));
 		else {
-			pr_debug("persistent_ram: found existing buffer,"
-				" size %zu, start %zu\n",
-			       buffer_size(prz), buffer_start(prz));
+			pr_debug("found existing buffer, size %zu, start %zu\n",
+				 buffer_size(prz), buffer_start(prz));
 			persistent_ram_save_old(prz);
 			return 0;
 		}
 	} else {
-		pr_debug("persistent_ram: no valid data in buffer"
-			" (sig = 0x%08x)\n", prz->buffer->sig);
+		pr_debug("no valid data in buffer (sig = 0x%08x)\n",
+			 prz->buffer->sig);
 	}
 
 	prz->buffer->sig = sig;
@@ -459,7 +507,7 @@ struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
 
 	prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
 	if (!prz) {
-		pr_err("persistent_ram: failed to allocate persistent ram zone\n");
+		pr_err("failed to allocate persistent ram zone\n");
 		goto err;
 	}