1 files changed, 52 insertions, 2 deletions

diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index 59337326e288..de272d426763 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -46,7 +46,7 @@ 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;
@@ -62,7 +62,7 @@ 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 +78,53 @@ 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)
 {
@@ -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);
 }