Drivers: hv: ring_buffer: remove code duplication from hv_ringbuffer_peek/read()

hv_ringbuffer_peek() does the same as hv_ringbuffer_read() without
advancing the read index. The only functional change this patch brings
is moving hv_need_to_signal_on_read() call under the ring_lock but this
function is just a couple of comparisons.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 7bca513..07f9408 100644 (file)
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -380,47 +380,9 @@ int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
        return 0;
 }
 
-
-/* Read without advancing the read index. */
-int hv_ringbuffer_peek(struct hv_ring_buffer_info *Inring_info,
-                  void *Buffer, u32 buflen)
-{
-       u32 bytes_avail_towrite;
-       u32 bytes_avail_toread;
-       u32 next_read_location = 0;
-       unsigned long flags;
-
-       spin_lock_irqsave(&Inring_info->ring_lock, flags);
-
-       hv_get_ringbuffer_availbytes(Inring_info,
-                               &bytes_avail_toread,
-                               &bytes_avail_towrite);
-
-       /* Make sure there is something to read */
-       if (bytes_avail_toread < buflen) {
-
-               spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
-
-               return -EAGAIN;
-       }
-
-       /* Convert to byte offset */
-       next_read_location = hv_get_next_read_location(Inring_info);
-
-       next_read_location = hv_copyfrom_ringbuffer(Inring_info,
-                                               Buffer,
-                                               buflen,
-                                               next_read_location);
-
-       spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
-
-       return 0;
-}
-
-
-/* Read and advance the read index. */
-int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, void *buffer,
-                  u32 buflen, u32 offset, bool *signal)
+static inline int __hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info,
+                                      void *buffer, u32 buflen, u32 offset,
+                                      bool *signal, bool advance)
 {
        u32 bytes_avail_towrite;
        u32 bytes_avail_toread;
@@ -452,6 +414,9 @@ int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, void *buffer,
                                                buflen,
                                                next_read_location);
 
+       if (!advance)
+               goto out_unlock;
+
        next_read_location = hv_copyfrom_ringbuffer(inring_info,
                                                &prev_indices,
                                                sizeof(u64),
@@ -467,9 +432,26 @@ int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, void *buffer,
        /* Update the read index */
        hv_set_next_read_location(inring_info, next_read_location);
 
-       spin_unlock_irqrestore(&inring_info->ring_lock, flags);
-
        *signal = hv_need_to_signal_on_read(bytes_avail_towrite, inring_info);
 
+out_unlock:
+       spin_unlock_irqrestore(&inring_info->ring_lock, flags);
        return 0;
 }
+
+/* Read from ring buffer without advancing the read index. */
+int hv_ringbuffer_peek(struct hv_ring_buffer_info *inring_info,
+                      void *buffer, u32 buflen)
+{
+       return __hv_ringbuffer_read(inring_info, buffer, buflen,
+                                   0, NULL, false);
+}
+
+/* Read from ring buffer and advance the read index. */
+int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info,
+                      void *buffer, u32 buflen, u32 offset,
+                      bool *signal)
+{
+       return __hv_ringbuffer_read(inring_info, buffer, buflen,
+                                   offset, signal, true);
+}