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/sound/usb/mixer_quirks.h

#ifndef SND_USB_MIXER_QUIRKS_H
#define SND_USB_MIXER_QUIRKS_H

int snd_usb_mixer_apply_create_quirk(struct usb_mixer_interface *mixer);

void snd_emuusb_set_samplerate(struct snd_usb_audio *chip,
			       unsigned char samplerate_id);

void snd_usb_mixer_rc_memory_change(struct usb_mixer_interface *mixer,
				    int unitid);

void snd_usb_mixer_fu_apply_quirk(struct usb_mixer_interface *mixer,
				  struct usb_mixer_elem_info *cval, int unitid,
				  struct snd_kcontrol *kctl);

#endif /* SND_USB_MIXER_QUIRKS_H */