diff options
Diffstat (limited to 'drivers/hv/ring_buffer.c')
| -rw-r--r-- | drivers/hv/ring_buffer.c | 46 |
1 files changed, 20 insertions, 26 deletions
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index 3d215d9dec43..59a4aa86d1f3 100644 --- a/drivers/hv/ring_buffer.c +++ b/drivers/hv/ring_buffer.c @@ -283,7 +283,7 @@ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info) /* Write to the ring buffer. */ int hv_ringbuffer_write(struct vmbus_channel *channel, const struct kvec *kv_list, u32 kv_count, - u64 requestid) + u64 requestid, u64 *trans_id) { int i; u32 bytes_avail_towrite; @@ -294,7 +294,7 @@ int hv_ringbuffer_write(struct vmbus_channel *channel, unsigned long flags; struct hv_ring_buffer_info *outring_info = &channel->outbound; struct vmpacket_descriptor *desc = kv_list[0].iov_base; - u64 rqst_id = VMBUS_NO_RQSTOR; + u64 __trans_id, rqst_id = VMBUS_NO_RQSTOR; if (channel->rescind) return -ENODEV; @@ -353,7 +353,15 @@ int hv_ringbuffer_write(struct vmbus_channel *channel, } } desc = hv_get_ring_buffer(outring_info) + old_write; - desc->trans_id = (rqst_id == VMBUS_NO_RQSTOR) ? requestid : rqst_id; + __trans_id = (rqst_id == VMBUS_NO_RQSTOR) ? requestid : rqst_id; + /* + * Ensure the compiler doesn't generate code that reads the value of + * the transaction ID from the ring buffer, which is shared with the + * Hyper-V host and subject to being changed at any time. + */ + WRITE_ONCE(desc->trans_id, __trans_id); + if (trans_id) + *trans_id = __trans_id; /* Set previous packet start */ prev_indices = hv_get_ring_bufferindices(outring_info); @@ -421,7 +429,7 @@ int hv_ringbuffer_read(struct vmbus_channel *channel, memcpy(buffer, (const char *)desc + offset, packetlen); /* Advance ring index to next packet descriptor */ - __hv_pkt_iter_next(channel, desc, true); + __hv_pkt_iter_next(channel, desc); /* Notify host of update */ hv_pkt_iter_close(channel); @@ -457,22 +465,6 @@ static u32 hv_pkt_iter_avail(const struct hv_ring_buffer_info *rbi) } /* - * Get first vmbus packet without copying it out of the ring buffer - */ -struct vmpacket_descriptor *hv_pkt_iter_first_raw(struct vmbus_channel *channel) -{ - struct hv_ring_buffer_info *rbi = &channel->inbound; - - hv_debug_delay_test(channel, MESSAGE_DELAY); - - if (hv_pkt_iter_avail(rbi) < sizeof(struct vmpacket_descriptor)) - return NULL; - - return (struct vmpacket_descriptor *)(hv_get_ring_buffer(rbi) + rbi->priv_read_index); -} -EXPORT_SYMBOL_GPL(hv_pkt_iter_first_raw); - -/* * Get first vmbus packet from ring buffer after read_index * * If ring buffer is empty, returns NULL and no other action needed. @@ -483,11 +475,14 @@ struct vmpacket_descriptor *hv_pkt_iter_first(struct vmbus_channel *channel) struct vmpacket_descriptor *desc, *desc_copy; u32 bytes_avail, pkt_len, pkt_offset; - desc = hv_pkt_iter_first_raw(channel); - if (!desc) + hv_debug_delay_test(channel, MESSAGE_DELAY); + + bytes_avail = hv_pkt_iter_avail(rbi); + if (bytes_avail < sizeof(struct vmpacket_descriptor)) return NULL; + bytes_avail = min(rbi->pkt_buffer_size, bytes_avail); - bytes_avail = min(rbi->pkt_buffer_size, hv_pkt_iter_avail(rbi)); + desc = (struct vmpacket_descriptor *)(hv_get_ring_buffer(rbi) + rbi->priv_read_index); /* * Ensure the compiler does not use references to incoming Hyper-V values (which @@ -534,8 +529,7 @@ EXPORT_SYMBOL_GPL(hv_pkt_iter_first); */ struct vmpacket_descriptor * __hv_pkt_iter_next(struct vmbus_channel *channel, - const struct vmpacket_descriptor *desc, - bool copy) + const struct vmpacket_descriptor *desc) { struct hv_ring_buffer_info *rbi = &channel->inbound; u32 packetlen = desc->len8 << 3; @@ -548,7 +542,7 @@ __hv_pkt_iter_next(struct vmbus_channel *channel, rbi->priv_read_index -= dsize; /* more data? */ - return copy ? hv_pkt_iter_first(channel) : hv_pkt_iter_first_raw(channel); + return hv_pkt_iter_first(channel); } EXPORT_SYMBOL_GPL(__hv_pkt_iter_next); |