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/drivers/usb/phy/phy-generic.h

#ifndef _PHY_GENERIC_H_
#define _PHY_GENERIC_H_

#include <linux/usb/usb_phy_generic.h>
#include <linux/gpio/consumer.h>
#include <linux/regulator/consumer.h>

struct usb_phy_generic {
	struct usb_phy phy;
	struct device *dev;
	struct clk *clk;
	struct regulator *vcc;
	struct gpio_desc *gpiod_reset;
	struct gpio_desc *gpiod_vbus;
	struct regulator *vbus_draw;
	bool vbus_draw_enabled;
	unsigned long mA;
	unsigned int vbus;
};

int usb_gen_phy_init(struct usb_phy *phy);
void usb_gen_phy_shutdown(struct usb_phy *phy);

int usb_phy_gen_create_phy(struct device *dev, struct usb_phy_generic *nop,
		struct usb_phy_generic_platform_data *pdata);

#endif