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 fcab234796ef9f2807ae7a977856924551a3d725..56dd261f7142f3957aef255ffaec43ce38a05ee7 100644 (file)
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -639,6 +639,7 @@ int vmbus_sendpacket_ctl(struct vmbus_channel *channel, void *buffer,
        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 @@ int vmbus_sendpacket_ctl(struct vmbus_channel *channel, void *buffer,
        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 @@ int vmbus_sendpacket_pagebuffer_ctl(struct vmbus_channel *channel,
        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 @@ int vmbus_sendpacket_pagebuffer_ctl(struct vmbus_channel *channel,
        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 @@ int vmbus_sendpacket_mpb_desc(struct vmbus_channel *channel,
        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 @@ int vmbus_sendpacket_mpb_desc(struct vmbus_channel *channel,
        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 @@ int vmbus_sendpacket_multipagebuffer(struct vmbus_channel *channel,
        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 @@ int vmbus_sendpacket_multipagebuffer(struct vmbus_channel *channel,
        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 cf311be88cb4c3166a63f280728d639fba86d379..b40f429aaa136551142cc7be034be50c1d0caf42 100644 (file)
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -259,6 +259,7 @@ static struct vmbus_channel *alloc_channel(void)
                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 ac7aa303c37d2e590f2d8082895d031c5489c879..b9ea7f59036b7fe565e2b99d3243d7004b9df20a 100644 (file)
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -529,7 +529,7 @@ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info);
 
 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 1145f3b8e4e081410429b263f0abe71cac742587..5613e2b5cff7759861a1e2d7ad2748f7626d16da 100644 (file)
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -314,7 +314,7 @@ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
 
 /* 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 @@ int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
        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 @@ int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
         * 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 @@ int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
        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 c056f058dcf8674a767b6922ce64ee8b942a2d59..d23dab0d770ba8bcbe269ac294519716cd2c5e4f 100644 (file)
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -811,8 +811,24 @@ struct vmbus_channel {
         * 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 &