linux-kernel - [RFC PATCH 1/4] Drivers: hv: vmbus: Remove special code for unsolicited messages

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Date:   Mon, 28 Mar 2022 16:42:41 +0200
From:   "Andrea Parri (Microsoft)" <parri.andrea@...il.com>
To:     KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        Wei Hu <weh@...rosoft.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczynski <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     linux-hyperv@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "Andrea Parri (Microsoft)" <parri.andrea@...il.com>
Subject: [RFC PATCH 1/4] Drivers: hv: vmbus: Remove special code for unsolicited messages

vmbus_requestor has included code for handling unsolicited messages
since its introduction with commit e8b7db38449ac ("Drivers: hv: vmbus:
Add vmbus_requestor data structure for VMBus hardening"); such code was
motivated by the early use of vmbus_requestor from storvsc.  Since
storvsc moved to a tag-based mechanism to generate/retrieve request IDs
with commit bf5fd8cae3c8f ("scsi: storvsc: Use blk_mq_unique_tag() to
generate requestIDs"), the special handling of unsolicited messages in
vmbus_requestor is not useful and can be removed.

Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@...il.com>
---
 drivers/hv/channel.c | 13 +------------
 1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index dc5c35210c16a..a253eee3aeb1a 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -1243,11 +1243,7 @@ u64 vmbus_next_request_id(struct vmbus_channel *channel, u64 rqst_addr)
 
 	spin_unlock_irqrestore(&rqstor->req_lock, flags);
 
-	/*
-	 * Cannot return an ID of 0, which is reserved for an unsolicited
-	 * message from Hyper-V.
-	 */
-	return current_id + 1;
+	return current_id;
 }
 EXPORT_SYMBOL_GPL(vmbus_next_request_id);
 
@@ -1268,15 +1264,8 @@ u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id)
 	if (!channel->rqstor_size)
 		return VMBUS_NO_RQSTOR;
 
-	/* Hyper-V can send an unsolicited message with ID of 0 */
-	if (!trans_id)
-		return trans_id;
-
 	spin_lock_irqsave(&rqstor->req_lock, flags);
 
-	/* Data corresponding to trans_id is stored at trans_id - 1 */
-	trans_id--;
-
 	/* Invalid trans_id */
 	if (trans_id >= rqstor->size || !test_bit(trans_id, rqstor->req_bitmap)) {
 		spin_unlock_irqrestore(&rqstor->req_lock, flags);
-- 
2.25.1