621be0aeda
If a VM is flooded with more ingress packets than the guest OS can handle, the current virtio-net code will keep reading those packets and drop most of them as no space is available in the receive queue. This is an undesirable receive livelock, which is a waste of CPU and memory resources and potentially opens to DoS attacks. With this change, virtio-net uses the new netbe_rx_disable() function to disable ingress operation in the backend while the guest is short on RX buffers. Once the guest makes more buffers available to the RX virtqueue, ingress operation is enabled again by calling netbe_rx_enable(). Reviewed by: bryanv, jhb MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D20987
57 lines
1.9 KiB
C
57 lines
1.9 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2011 NetApp, Inc.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY NETAPP, INC ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL NETAPP, INC OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _MEVENT_H_
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#define _MEVENT_H_
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enum ev_type {
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EVF_READ,
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EVF_WRITE,
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EVF_TIMER,
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EVF_SIGNAL
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};
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struct mevent;
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struct mevent *mevent_add(int fd, enum ev_type type,
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void (*func)(int, enum ev_type, void *),
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void *param);
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struct mevent *mevent_add_disabled(int fd, enum ev_type type,
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void (*func)(int, enum ev_type, void *),
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void *param);
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int mevent_enable(struct mevent *evp);
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int mevent_disable(struct mevent *evp);
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int mevent_delete(struct mevent *evp);
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int mevent_delete_close(struct mevent *evp);
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void mevent_dispatch(void);
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#endif /* _MEVENT_H_ */
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