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>

path: root/include/dt-bindings/power/r8a7743-sysc.h

/*
 * Copyright (C) 2016 Cogent Embedded Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#ifndef __DT_BINDINGS_POWER_R8A7743_SYSC_H__
#define __DT_BINDINGS_POWER_R8A7743_SYSC_H__

/*
 * These power domain indices match the numbers of the interrupt bits
 * representing the power areas in the various Interrupt Registers
 * (e.g. SYSCISR, Interrupt Status Register)
 */

#define R8A7743_PD_CA15_CPU0		 0
#define R8A7743_PD_CA15_CPU1		 1
#define R8A7743_PD_CA15_SCU		12
#define R8A7743_PD_SGX			20

/* Always-on power area */
#define R8A7743_PD_ALWAYS_ON		32

#endif /* __DT_BINDINGS_POWER_R8A7743_SYSC_H__ */