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@xxxxxxxxxx>
---
drivers/hv/ring_buffer.c | 68 ++++++++++++++++++------------------------------
1 file changed, 25 insertions(+), 43 deletions(-)
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 7bca513..07f9408 100644
--- 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);
+}
--
2.4.3
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