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authorDexuan Cui <decui@microsoft.com>2017-01-28 21:46:02 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-01-31 12:59:48 +0300
commit433e19cf33d34bb6751c874a9c00980552fe508c (patch)
treece6547ef2987fbb289fa28f03536328a42781651 /drivers/hv/ring_buffer.c
parent191e885a2e130e639bb0c8ee350d7047294f2ce6 (diff)
downloadlinux-433e19cf33d34bb6751c874a9c00980552fe508c.tar.xz
Drivers: hv: vmbus: finally fix hv_need_to_signal_on_read()
Commit a389fcfd2cb5 ("Drivers: hv: vmbus: Fix signaling logic in hv_need_to_signal_on_read()") added the proper mb(), but removed the test "prev_write_sz < pending_sz" when making the signal decision. As a result, the guest can signal the host unnecessarily, and then the host can throttle the guest because the host thinks the guest is buggy or malicious; finally the user running stress test can perceive intermittent freeze of the guest. This patch brings back the test, and properly handles the in-place consumption APIs used by NetVSC (see get_next_pkt_raw(), put_pkt_raw() and commit_rd_index()). Fixes: a389fcfd2cb5 ("Drivers: hv: vmbus: Fix signaling logic in hv_need_to_signal_on_read()") Signed-off-by: Dexuan Cui <decui@microsoft.com> Reported-by: Rolf Neugebauer <rolf.neugebauer@docker.com> Tested-by: Rolf Neugebauer <rolf.neugebauer@docker.com> Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Stephen Hemminger <sthemmin@microsoft.com> Cc: <stable@vger.kernel.org> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/hv/ring_buffer.c')
-rw-r--r--drivers/hv/ring_buffer.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index cd49cb17eb7f..308dbda700eb 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -383,6 +383,7 @@ int hv_ringbuffer_read(struct vmbus_channel *channel,
return ret;
}
+ init_cached_read_index(channel);
next_read_location = hv_get_next_read_location(inring_info);
next_read_location = hv_copyfrom_ringbuffer(inring_info, &desc,
sizeof(desc),