423 lines
13 KiB
C
423 lines
13 KiB
C
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/*-
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* Copyright (c) 2001 Luigi Rizzo
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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 THE AUTHORS AND CONTRIBUTORS ``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 THE AUTHORS 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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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/socket.h> /* needed by net/if.h */
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#include <sys/sysctl.h>
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#include <net/if.h> /* for IFF_* flags */
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#include <net/netisr.h> /* for NETISR_POLL */
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#ifdef SMP
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#error DEVICE_POLLING is not compatible with SMP
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#endif
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void ether_poll1(void);
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void ether_poll(int); /* polling while in trap */
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void ether_pollmore(void);
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void hardclock_device_poll(void);
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/*
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* Polling support for [network] device drivers.
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*
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* Drivers which support this feature try to register with the
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* polling code.
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*
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* If registration is successful, the driver must disable interrupts,
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* and further I/O is performed through the handler, which is invoked
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* (at least once per clock tick) with 3 arguments: the "arg" passed at
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* register time (a struct ifnet pointer), a command, and a "count" limit.
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*
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* The command can be one of the following:
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* POLL_ONLY: quick move of "count" packets from input/output queues.
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* POLL_AND_CHECK_STATUS: as above, plus check status registers or do
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* other more expensive operations. This command is issued periodically
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* but less frequently than POLL_ONLY.
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* POLL_DEREGISTER: deregister and return to interrupt mode.
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*
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* The first two commands are only issued if the interface is marked as
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* 'IFF_UP and IFF_RUNNING', the last one only if IFF_RUNNING is set.
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*
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* The count limit specifies how much work the handler can do during the
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* call -- typically this is the number of packets to be received, or
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* transmitted, etc. (drivers are free to interpret this number, as long
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* as the max time spent in the function grows roughly linearly with the
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* count).
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*
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* Deregistration can be requested by the driver itself (typically in the
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* *_stop() routine), or by the polling code, by invoking the handler.
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*
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* Polling can be globally enabled or disabled with the sysctl variable
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* kern.polling.enable (default is 0, disabled)
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*
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* A second variable controls the sharing of CPU between polling/kernel
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* network processing, and other activities (typically userlevel tasks):
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* kern.polling.user_frac (between 0 and 100, default 50) sets the share
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* of CPU allocated to user tasks. CPU is allocated proportionally to the
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* shares, by dynamically adjusting the "count" (poll_burst).
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*
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* Other parameters can should be left to their default values.
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* The following constraints hold
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*
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* 1 <= poll_each_burst <= poll_burst <= poll_burst_max
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* 0 <= poll_in_trap <= poll_each_burst
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* MIN_POLL_BURST_MAX <= poll_burst_max <= MAX_POLL_BURST_MAX
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*/
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#define MIN_POLL_BURST_MAX 10
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#define MAX_POLL_BURST_MAX 1000
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SYSCTL_NODE(_kern, OID_AUTO, polling, CTLFLAG_RW, 0,
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"Device polling parameters");
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static u_int32_t poll_burst = 5;
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SYSCTL_ULONG(_kern_polling, OID_AUTO, burst, CTLFLAG_RW,
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&poll_burst, 0, "Current polling burst size");
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static u_int32_t poll_each_burst = 5;
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SYSCTL_ULONG(_kern_polling, OID_AUTO, each_burst, CTLFLAG_RW,
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&poll_each_burst, 0, "Max size of each burst");
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static u_int32_t poll_burst_max = 150; /* good for 100Mbit net and HZ=1000 */
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SYSCTL_ULONG(_kern_polling, OID_AUTO, burst_max, CTLFLAG_RW,
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&poll_burst_max, 0, "Max Polling burst size");
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u_int32_t poll_in_trap; /* used in trap.c */
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SYSCTL_ULONG(_kern_polling, OID_AUTO, poll_in_trap, CTLFLAG_RW,
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&poll_in_trap, 0, "Poll burst size during a trap");
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static u_int32_t user_frac = 50;
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SYSCTL_ULONG(_kern_polling, OID_AUTO, user_frac, CTLFLAG_RW,
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&user_frac, 0, "Desired user fraction of cpu time");
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static u_int32_t reg_frac = 20 ;
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SYSCTL_ULONG(_kern_polling, OID_AUTO, reg_frac, CTLFLAG_RW,
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®_frac, 0, "Every this many cycles poll register");
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static u_int32_t short_ticks;
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SYSCTL_ULONG(_kern_polling, OID_AUTO, short_ticks, CTLFLAG_RW,
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&short_ticks, 0, "Hardclock ticks shorter than they should be");
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static u_int32_t lost_polls;
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SYSCTL_ULONG(_kern_polling, OID_AUTO, lost_polls, CTLFLAG_RW,
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&lost_polls, 0, "How many times we would have lost a poll tick");
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static u_int32_t poll_handlers; /* next free entry in pr[]. */
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SYSCTL_ULONG(_kern_polling, OID_AUTO, handlers, CTLFLAG_RD,
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&poll_handlers, 0, "Number of registered poll handlers");
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static int polling = 0; /* global polling enable */
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SYSCTL_ULONG(_kern_polling, OID_AUTO, enable, CTLFLAG_RW,
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&polling, 0, "Polling enabled");
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static u_int32_t poll1_active;
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static u_int32_t need_poll_again;
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#define POLL_LIST_LEN 128
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struct pollrec {
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poll_handler_t *handler;
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struct ifnet *ifp;
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};
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static struct pollrec pr[POLL_LIST_LEN];
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/*
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* Hook from hardclock. Tries to schedule a netisr, but keeps track
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* of lost ticks due to the previous handler taking too long.
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* The first part of the code is just for debugging purposes, and tries
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* to count how often hardclock ticks are shorter than they should,
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* meaning either stray interrupts or delayed events.
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*/
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void
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hardclock_device_poll(void)
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{
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static struct timeval prev_t, t;
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int delta;
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microuptime(&t);
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delta = (t.tv_usec - prev_t.tv_usec) +
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(t.tv_sec - prev_t.tv_sec)*1000000;
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if (delta * hz < 500000)
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short_ticks++;
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else
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prev_t = t;
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if (poll_handlers > 0) {
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if (poll1_active) {
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lost_polls++;
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need_poll_again++;
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} else {
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poll1_active = 1;
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schednetisr(NETISR_POLL);
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}
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}
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}
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/*
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* ether_poll is called from the idle loop or from the trap handler.
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*/
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void
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ether_poll(int count)
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{
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int i;
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int s = splimp();
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mtx_lock(&Giant);
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if (count > poll_each_burst)
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count = poll_each_burst;
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for (i = 0 ; i < poll_handlers ; i++)
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if (pr[i].handler && (IFF_UP|IFF_RUNNING) ==
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(pr[i].ifp->if_flags & (IFF_UP|IFF_RUNNING)) )
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pr[i].handler(pr[i].ifp, 0, count); /* quick check */
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mtx_unlock(&Giant);
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splx(s);
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}
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/*
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* ether_pollmore is called after other netisr's, possibly scheduling
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* another NETISR_POLL call, or adapting the burst size for the next cycle.
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*
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* It is very bad to fetch large bursts of packets from a single card at once,
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* because the burst could take a long time to be completely processed, or
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* could saturate the intermediate queue (ipintrq or similar) leading to
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* losses or unfairness. To reduce the problem, and also to account better for
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* time spent in network-related processnig, we split the burst in smaller
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* chunks of fixed size, giving control to the other netisr's between chunks.
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* This helps in improving the fairness, reducing livelock (because we
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* emulate more closely the "process to completion" that we have with
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* fastforwarding) and accounting for the work performed in low level
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* handling and forwarding.
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*/
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static int residual_burst = 0;
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static struct timeval poll_start_t;
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void
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ether_pollmore()
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{
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struct timeval t;
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int kern_load;
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int s = splhigh();
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if (residual_burst > 0) {
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schednetisr(NETISR_POLL);
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/* will run immediately on return, followed by netisrs */
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splx(s);
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return ;
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}
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/* here we can account time spent in netisr's in this tick */
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microuptime(&t);
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kern_load = (t.tv_usec - poll_start_t.tv_usec) +
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(t.tv_sec - poll_start_t.tv_sec)*1000000; /* us */
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kern_load = (kern_load * hz) / 10000; /* 0..100 */
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if (kern_load > (100 - user_frac)) { /* try decrease ticks */
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if (poll_burst > 1)
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poll_burst--;
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} else {
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if (poll_burst < poll_burst_max)
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poll_burst++;
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}
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if (need_poll_again) {
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/*
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* Last cycle was long and caused us to miss one or more
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* hardclock ticks. Restart processnig again, but slightly
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* reduce the burst size to prevent that this happens again.
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*/
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need_poll_again--;
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poll_burst -= (poll_burst / 8);
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if (poll_burst < 1)
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poll_burst = 1;
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schednetisr(NETISR_POLL);
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} else
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poll1_active = 0;
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splx(s);
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}
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/*
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* ether_poll1 is called by schednetisr when appropriate, typically once
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* per tick. It is called at splnet() so first thing to do is to upgrade to
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* splimp(), and call all registered handlers.
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*/
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void
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ether_poll1(void)
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{
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static int reg_frac_count;
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int i, cycles;
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enum poll_cmd arg = POLL_ONLY;
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int s=splimp();
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mtx_lock(&Giant);
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if (residual_burst == 0) { /* first call in this tick */
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microuptime(&poll_start_t);
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/*
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* Check that paremeters are consistent with runtime
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* variables. Some of these tests could be done at sysctl
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* time, but the savings would be very limited because we
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* still have to check against reg_frac_count and
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* poll_each_burst. So, instead of writing separate sysctl
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* handlers, we do all here.
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*/
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if (reg_frac > hz)
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reg_frac = hz;
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else if (reg_frac < 1)
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reg_frac = 1;
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if (reg_frac_count > reg_frac)
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reg_frac_count = reg_frac - 1;
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if (reg_frac_count-- == 0) {
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arg = POLL_AND_CHECK_STATUS;
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reg_frac_count = reg_frac - 1;
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}
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if (poll_burst_max < MIN_POLL_BURST_MAX)
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poll_burst_max = MIN_POLL_BURST_MAX;
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else if (poll_burst_max > MAX_POLL_BURST_MAX)
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poll_burst_max = MAX_POLL_BURST_MAX;
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if (poll_each_burst < 1)
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poll_each_burst = 1;
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else if (poll_each_burst > poll_burst_max)
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poll_each_burst = poll_burst_max;
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residual_burst = poll_burst;
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}
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cycles = (residual_burst < poll_each_burst) ?
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residual_burst : poll_each_burst;
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residual_burst -= cycles;
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if (polling) {
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for (i = 0 ; i < poll_handlers ; i++)
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if (pr[i].handler && (IFF_UP|IFF_RUNNING) ==
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(pr[i].ifp->if_flags & (IFF_UP|IFF_RUNNING)) )
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pr[i].handler(pr[i].ifp, arg, cycles);
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} else { /* unregister */
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for (i = 0 ; i < poll_handlers ; i++) {
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if (pr[i].handler &&
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pr[i].ifp->if_flags & IFF_RUNNING) {
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pr[i].ifp->if_ipending &= ~IFF_POLLING;
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pr[i].handler(pr[i].ifp, POLL_DEREGISTER, 1);
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}
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pr[i].handler=NULL;
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}
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residual_burst = 0;
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poll_handlers = 0;
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}
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/* on -stable, schednetisr(NETISR_POLLMORE); */
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mtx_unlock(&Giant);
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splx(s);
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}
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/*
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* Try to register routine for polling. Returns 1 if successful
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* (and polling should be enabled), 0 otherwise.
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* A device is not supposed to register itself multiple times.
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*
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* This is called from within the *_intr() function, so we should
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* probably not need further locking. XXX
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*/
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int
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ether_poll_register(poll_handler_t *h, struct ifnet *ifp)
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{
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int s;
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if (polling == 0) /* polling disabled, cannot register */
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return 0;
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if (h == NULL || ifp == NULL) /* bad arguments */
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return 0;
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if ( !(ifp->if_flags & IFF_UP) ) /* must be up */
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return 0;
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if (ifp->if_ipending & IFF_POLLING) /* already polling */
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return 0;
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s = splhigh();
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if (poll_handlers >= POLL_LIST_LEN) {
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/*
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* List full, cannot register more entries.
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* This should never happen; if it does, it is probably a
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* broken driver trying to register multiple times. Checking
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* this at runtime is expensive, and won't solve the problem
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* anyways, so just report a few times and then give up.
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*/
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static int verbose = 10 ;
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splx(s);
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if (verbose >0) {
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printf("poll handlers list full, "
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"maybe a broken driver ?\n");
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verbose--;
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}
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return 0; /* no polling for you */
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}
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pr[poll_handlers].handler = h;
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pr[poll_handlers].ifp = ifp;
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poll_handlers++;
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ifp->if_ipending |= IFF_POLLING;
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splx(s);
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return 1; /* polling enabled in next call */
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}
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/*
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* Remove the interface from the list of polling ones.
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* Normally run by *_stop().
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* We allow it being called with IFF_POLLING clear, the
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* call is sufficiently rare so it is preferable to save the
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* space for the extra test in each device in exchange of one
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* additional function call.
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*/
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int
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ether_poll_deregister(struct ifnet *ifp)
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{
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int i;
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mtx_lock(&Giant);
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if ( !ifp || !(ifp->if_ipending & IFF_POLLING) ) {
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mtx_unlock(&Giant);
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return 0;
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}
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for (i = 0 ; i < poll_handlers ; i++)
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if (pr[i].ifp == ifp) /* found it */
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break;
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ifp->if_ipending &= ~IFF_POLLING; /* found or not... */
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if (i == poll_handlers) {
|
||
|
mtx_unlock(&Giant);
|
||
|
printf("ether_poll_deregister: ifp not found!!!\n");
|
||
|
return 0;
|
||
|
}
|
||
|
poll_handlers--;
|
||
|
if (i < poll_handlers) { /* Last entry replaces this one. */
|
||
|
pr[i].handler = pr[poll_handlers].handler;
|
||
|
pr[i].ifp = pr[poll_handlers].ifp;
|
||
|
}
|
||
|
mtx_unlock(&Giant);
|
||
|
return 1;
|
||
|
}
|