Drivers: hv: vmbus: Give control over how the ring access is serialized
On the channel send side, many of the VMBUS
device drivers explicity serialize access to the
outgoing ring buffer. Give more control to the
VMBUS device drivers in terms how to serialize
accesss to the outgoing ring buffer.
The default behavior will be to aquire the
ring lock to preserve the current behavior.
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index fcab234..56dd261 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -639,6 +639,7 @@
u64 aligned_data = 0;
int ret;
bool signal = false;
+ bool lock = channel->acquire_ring_lock;
int num_vecs = ((bufferlen != 0) ? 3 : 1);
@@ -658,7 +659,7 @@
bufferlist[2].iov_len = (packetlen_aligned - packetlen);
ret = hv_ringbuffer_write(&channel->outbound, bufferlist, num_vecs,
- &signal);
+ &signal, lock);
/*
* Signalling the host is conditional on many factors:
@@ -738,6 +739,7 @@
struct kvec bufferlist[3];
u64 aligned_data = 0;
bool signal = false;
+ bool lock = channel->acquire_ring_lock;
if (pagecount > MAX_PAGE_BUFFER_COUNT)
return -EINVAL;
@@ -774,7 +776,8 @@
bufferlist[2].iov_base = &aligned_data;
bufferlist[2].iov_len = (packetlen_aligned - packetlen);
- ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3, &signal);
+ ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3,
+ &signal, lock);
/*
* Signalling the host is conditional on many factors:
@@ -837,6 +840,7 @@
struct kvec bufferlist[3];
u64 aligned_data = 0;
bool signal = false;
+ bool lock = channel->acquire_ring_lock;
packetlen = desc_size + bufferlen;
packetlen_aligned = ALIGN(packetlen, sizeof(u64));
@@ -856,7 +860,8 @@
bufferlist[2].iov_base = &aligned_data;
bufferlist[2].iov_len = (packetlen_aligned - packetlen);
- ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3, &signal);
+ ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3,
+ &signal, lock);
if (ret == 0 && signal)
vmbus_setevent(channel);
@@ -881,6 +886,7 @@
struct kvec bufferlist[3];
u64 aligned_data = 0;
bool signal = false;
+ bool lock = channel->acquire_ring_lock;
u32 pfncount = NUM_PAGES_SPANNED(multi_pagebuffer->offset,
multi_pagebuffer->len);
@@ -919,7 +925,8 @@
bufferlist[2].iov_base = &aligned_data;
bufferlist[2].iov_len = (packetlen_aligned - packetlen);
- ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3, &signal);
+ ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3,
+ &signal, lock);
if (ret == 0 && signal)
vmbus_setevent(channel);
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index cf311be..b40f429 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -259,6 +259,7 @@
return NULL;
channel->id = atomic_inc_return(&chan_num);
+ channel->acquire_ring_lock = true;
spin_lock_init(&channel->inbound_lock);
spin_lock_init(&channel->lock);
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index ac7aa30..b9ea7f5 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -529,7 +529,7 @@
int hv_ringbuffer_write(struct hv_ring_buffer_info *ring_info,
struct kvec *kv_list,
- u32 kv_count, bool *signal);
+ u32 kv_count, bool *signal, bool lock);
int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info,
void *buffer, u32 buflen, u32 *buffer_actual_len,
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 1145f3b..5613e2b 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -314,7 +314,7 @@
/* Write to the ring buffer. */
int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
- struct kvec *kv_list, u32 kv_count, bool *signal)
+ struct kvec *kv_list, u32 kv_count, bool *signal, bool lock)
{
int i = 0;
u32 bytes_avail_towrite;
@@ -324,14 +324,15 @@
u32 next_write_location;
u32 old_write;
u64 prev_indices = 0;
- unsigned long flags;
+ unsigned long flags = 0;
for (i = 0; i < kv_count; i++)
totalbytes_towrite += kv_list[i].iov_len;
totalbytes_towrite += sizeof(u64);
- spin_lock_irqsave(&outring_info->ring_lock, flags);
+ if (lock)
+ spin_lock_irqsave(&outring_info->ring_lock, flags);
hv_get_ringbuffer_availbytes(outring_info,
&bytes_avail_toread,
@@ -343,7 +344,8 @@
* is empty since the read index == write index.
*/
if (bytes_avail_towrite <= totalbytes_towrite) {
- spin_unlock_irqrestore(&outring_info->ring_lock, flags);
+ if (lock)
+ spin_unlock_irqrestore(&outring_info->ring_lock, flags);
return -EAGAIN;
}
@@ -374,7 +376,8 @@
hv_set_next_write_location(outring_info, next_write_location);
- spin_unlock_irqrestore(&outring_info->ring_lock, flags);
+ if (lock)
+ spin_unlock_irqrestore(&outring_info->ring_lock, flags);
*signal = hv_need_to_signal(old_write, outring_info);
return 0;
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index c056f05..d23dab0 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -811,8 +811,24 @@
* signaling control.
*/
enum hv_signal_policy signal_policy;
+ /*
+ * On the channel send side, many of the VMBUS
+ * device drivers explicity serialize access to the
+ * outgoing ring buffer. Give more control to the
+ * VMBUS device drivers in terms how to serialize
+ * accesss to the outgoing ring buffer.
+ * The default behavior will be to aquire the
+ * ring lock to preserve the current behavior.
+ */
+ bool acquire_ring_lock;
+
};
+static inline void set_channel_lock_state(struct vmbus_channel *c, bool state)
+{
+ c->acquire_ring_lock = state;
+}
+
static inline bool is_hvsock_channel(const struct vmbus_channel *c)
{
return !!(c->offermsg.offer.chn_flags &
