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Groups > linux.kernel > #1275627 > unrolled thread
| Started by | Vitaly Kuznetsov <vkuznets@redhat.com> |
|---|---|
| First post | 2015-11-23 17:50 +0100 |
| Last post | 2015-11-23 17:50 +0100 |
| Articles | 3 — 1 participant |
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[PATCH 0/3] Drivers: hv: ring_buffer: do some code cleanup Vitaly Kuznetsov <vkuznets@redhat.com> - 2015-11-23 17:50 +0100
[PATCH 3/3] Drivers: hv: ring_buffer: remove code duplication from hv_ringbuffer_peek/read() Vitaly Kuznetsov <vkuznets@redhat.com> - 2015-11-23 17:50 +0100
[PATCH 2/3] Drivers: hv: ring_buffer: remove stray smp_read_barrier_depends() Vitaly Kuznetsov <vkuznets@redhat.com> - 2015-11-23 17:50 +0100
| From | Vitaly Kuznetsov <vkuznets@redhat.com> |
|---|---|
| Date | 2015-11-23 17:50 +0100 |
| Subject | [PATCH 0/3] Drivers: hv: ring_buffer: do some code cleanup |
| Message-ID | <qy2tr-4pB-3@gated-at.bofh.it> |
1) Fix comment style in ring_buffer.c
2) Remove unneeded smp_read_barrier_depends() from hyperv.h
3) Unify hv_ringbuffer_peek/read() functions.
Vitaly Kuznetsov (3):
Drivers: hv: ring_buffer.c: fix comment style
Drivers: hv: ring_buffer: remove stray smp_read_barrier_depends()
Drivers: hv: ring_buffer: remove code duplication from
hv_ringbuffer_peek/read()
drivers/hv/ring_buffer.c | 199 ++++++++++++-----------------------------------
include/linux/hyperv.h | 2 -
2 files changed, 49 insertions(+), 152 deletions(-)
--
2.4.3
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| From | Vitaly Kuznetsov <vkuznets@redhat.com> |
|---|---|
| Date | 2015-11-23 17:50 +0100 |
| Subject | [PATCH 3/3] Drivers: hv: ring_buffer: remove code duplication from hv_ringbuffer_peek/read() |
| Message-ID | <qy2tt-4pB-47@gated-at.bofh.it> |
| In reply to | #1275627 |
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>
---
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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| From | Vitaly Kuznetsov <vkuznets@redhat.com> |
|---|---|
| Date | 2015-11-23 17:50 +0100 |
| Subject | [PATCH 2/3] Drivers: hv: ring_buffer: remove stray smp_read_barrier_depends() |
| Message-ID | <qy2tt-4pB-49@gated-at.bofh.it> |
| In reply to | #1275627 |
smp_read_barrier_depends() does nothing on almost all arcitectures
including x86 and having it in the beginning of
hv_get_ringbuffer_availbytes() does not provide any guarantees anyway.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
include/linux/hyperv.h | 2 --
1 file changed, 2 deletions(-)
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 8fdc17b..1777dc8 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -141,8 +141,6 @@ hv_get_ringbuffer_availbytes(struct hv_ring_buffer_info *rbi,
{
u32 read_loc, write_loc, dsize;
- smp_read_barrier_depends();
-
/* Capture the read/write indices before they changed */
read_loc = rbi->ring_buffer->read_index;
write_loc = rbi->ring_buffer->write_index;
--
2.4.3
--
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