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Patch "vmbus: eliminate duplicate cached index" has been added to the 4.13-stable tree

PATCH [email protected] 1 participant 1 message Oct 19, 2017

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This is a note to let you know that I've just added the patch titled

vmbus: eliminate duplicate cached index

to the 4.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
vmbus-eliminate-duplicate-cached-index.patch
and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 05d00bc94ac27d220d8a78e365d7fa3a26dcca17 Mon Sep 17 00:00:00 2001

From: Stephen Hemminger <[email protected]>
Date: Sun, 25 Jun 2017 12:30:27 -0700
Subject: vmbus: eliminate duplicate cached index

From: Stephen Hemminger <[email protected]>

commit 05d00bc94ac27d220d8a78e365d7fa3a26dcca17 upstream.

Don't need cached read index anymore now that packet iterator is used. The iterator has the original read index until the visible read_index is updated.

Signed-off-by Stephen Hemminger <[email protected]>
Signed-off-by K. Y. Srinivasan <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 drivers/hv/ring_buffer.c |   17 ++++-------------
 include/linux/hyperv.h   |   14 --------------
 2 files changed, 4 insertions(+), 27 deletions(-)
drivers/hv/ring_buffer.c +4 -13
@@ -358,9 +358,6 @@ struct vmpacket_descriptor *hv_pkt_iter_
 {
 	struct hv_ring_buffer_info *rbi = &channel->inbound;
 
-	/* set state for later hv_pkt_iter_close */
-	rbi->cached_read_index = rbi->ring_buffer->read_index;
-
 	if (hv_pkt_iter_avail(rbi) < sizeof(struct vmpacket_descriptor))
 		return NULL;
 

@@ -388,10 +385,7 @@ __hv_pkt_iter_next(struct vmbus_channel
 		rbi->priv_read_index -= dsize;
 
 	/* more data? */
-	if (hv_pkt_iter_avail(rbi) < sizeof(struct vmpacket_descriptor))
-		return NULL;
-	else
-		return hv_get_ring_buffer(rbi) + rbi->priv_read_index;
+	return hv_pkt_iter_first(channel);
 }
 EXPORT_SYMBOL_GPL(__hv_pkt_iter_next);
 

@@ -401,7 +395,7 @@ EXPORT_SYMBOL_GPL(__hv_pkt_iter_next);
 void hv_pkt_iter_close(struct vmbus_channel *channel)
 {
 	struct hv_ring_buffer_info *rbi = &channel->inbound;
-	u32 cur_write_sz, cached_write_sz;
+	u32 orig_write_sz = hv_get_bytes_to_write(rbi);
 	u32 pending_sz;
 
 	/*

@@ -430,13 +424,10 @@ void hv_pkt_iter_close(struct vmbus_chan
 	if (pending_sz == 0)
 		return;
 
-	cur_write_sz = hv_get_bytes_to_write(rbi);
-
-	if (cur_write_sz < pending_sz)
+	if (hv_get_bytes_to_write(rbi) < pending_sz)
 		return;
 
-	cached_write_sz = hv_get_cached_bytes_to_write(rbi);
-	if (cached_write_sz < pending_sz)
+	if (orig_write_sz < pending_sz)
 		vmbus_setevent(channel);
 }
 EXPORT_SYMBOL_GPL(hv_pkt_iter_close);
include/linux/hyperv.h +0 -14
@@ -127,7 +127,6 @@ struct hv_ring_buffer_info {
 	u32 ring_data_startoffset;
 	u32 priv_write_index;
 	u32 priv_read_index;
-	u32 cached_read_index;
 };
 
 /*

@@ -180,19 +179,6 @@ static inline u32 hv_get_bytes_to_write(
 	return write;
 }
 
-static inline u32 hv_get_cached_bytes_to_write(
-	const struct hv_ring_buffer_info *rbi)
-{
-	u32 read_loc, write_loc, dsize, write;
-
-	dsize = rbi->ring_datasize;
-	read_loc = rbi->cached_read_index;
-	write_loc = rbi->ring_buffer->write_index;
-
-	write = write_loc >= read_loc ? dsize - (write_loc - read_loc) :
-		read_loc - write_loc;
-	return write;
-}
 /*
  * VMBUS version is 32 bit entity broken up into
  * two 16 bit quantities: major_number. minor_number.

Patches currently in stable-queue which might be from [email protected] are

queue-4.13/vmbus-more-host-signalling-avoidance.patch queue-4.13/vmbus-refactor-hv_signal_on_read.patch queue-4.13/vmbus-simplify-hv_ringbuffer_read.patch queue-4.13/vmbus-eliminate-duplicate-cached-index.patch