LinuxKPI: netdev: expose napi state
There are drivers directly accessing napi->state testing for bits (NAPI_STATE_SCHED encountered so far). Rename the internal _flags struct field to state and expose our internal state flag bits along with the one official aliased. As I left in a comment, I wished Linux would hide these accesses behind inline functions or by other means and not public expose the implementation details. MFC after: 1 week
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@ -5,7 +5,7 @@
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* Copyright (c) 2013-2019 Mellanox Technologies, Ltd.
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* All rights reserved.
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* Copyright (c) 2020-2021 The FreeBSD Foundation
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* Copyright (c) 2020-2021 Bjoern A. Zeeb
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* Copyright (c) 2020-2022 Bjoern A. Zeeb
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*
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* Portions of this software were developed by Björn Zeeb
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* under sponsorship from the FreeBSD Foundation.
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@ -182,6 +182,30 @@ int unregister_inetaddr_notifier(struct notifier_block *);
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#define NAPI_POLL_WEIGHT 64 /* budget */
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/*
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* There are drivers directly testing napi state bits, so we need to publicly
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* expose them. If you ask me, those accesses should be hid behind an
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* inline function and the bit flags not be directly exposed.
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*/
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enum napi_state_bits {
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/*
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* Official Linux flags encountered.
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*/
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NAPI_STATE_SCHED = 1,
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/*
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* Our internal versions (for now).
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*/
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/* Do not schedule new things while we are waiting to clear things. */
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LKPI_NAPI_FLAG_DISABLE_PENDING = 0,
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/* To synchronise that only one poll is ever running. */
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LKPI_NAPI_FLAG_IS_SCHEDULED = 1,
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/* If trying to schedule while poll is running. Need to re-schedule. */
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LKPI_NAPI_FLAG_LOST_RACE_TRY_AGAIN = 2,
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/* When shutting down forcefully prevent anything from running task/poll. */
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LKPI_NAPI_FLAG_SHUTDOWN = 3,
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};
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struct napi_struct {
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TAILQ_ENTRY(napi_struct) entry;
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@ -191,11 +215,12 @@ struct napi_struct {
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int budget;
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int rx_count;
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/*
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* These flags mostly need to be checked/changed atomically
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* (multiple together in some cases).
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*/
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volatile unsigned long _flags;
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volatile unsigned long state;
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/* FreeBSD internal. */
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/* Use task for now, so we can easily switch between direct and task. */
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@ -1,5 +1,6 @@
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/*-
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* Copyright (c) 2021 The FreeBSD Foundation
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* Copyright (c) 2022 Bjoern A. Zeeb
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*
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* This software was developed by Björn Zeeb under sponsorship from
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* the FreeBSD Foundation.
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@ -48,14 +49,6 @@ MALLOC_DEFINE(M_NETDEV, "lkpindev", "Linux KPI netdevice compat");
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#define NAPI_UNLOCK(_ndev) mtx_unlock(&(_ndev)->napi_mtx)
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/* -------------------------------------------------------------------------- */
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/* Do not schedule new things while we are waiting to clear things. */
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#define LKPI_NAPI_FLAG_DISABLE_PENDING 0
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/* To synchronise that only one poll is ever running. */
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#define LKPI_NAPI_FLAG_IS_SCHEDULED 1
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/* If trying to schedule while poll is running. Need to re-schedule. */
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#define LKPI_NAPI_FLAG_LOST_RACE_TRY_AGAIN 2
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/* When shutting down forcefully prevent anything from running task/poll. */
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#define LKPI_NAPI_FLAG_SHUTDOWN 3
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#define LKPI_NAPI_FLAGS \
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"\20\1DISABLE_PENDING\2IS_SCHEDULED\3LOST_RACE_TRY_AGAIN"
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@ -74,17 +67,17 @@ SYSCTL_INT(_compat_linuxkpi, OID_AUTO, debug_napi, CTLFLAG_RWTUN,
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#define NAPI_TRACE(_n) if (debug_napi & DNAPI_TRACE) \
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printf("NAPI_TRACE %s:%d %u %p (%#jx %b)\n", __func__, __LINE__, \
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(unsigned int)ticks, _n, (uintmax_t)(_n)->_flags, \
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(int)(_n)->_flags, LKPI_NAPI_FLAGS)
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(unsigned int)ticks, _n, (uintmax_t)(_n)->state, \
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(int)(_n)->state, LKPI_NAPI_FLAGS)
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#define NAPI_TRACE2D(_n, _d) if (debug_napi & DNAPI_TRACE) \
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printf("NAPI_TRACE %s:%d %u %p (%#jx %b) %d\n", __func__, __LINE__, \
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(unsigned int)ticks, _n, (uintmax_t)(_n)->_flags, \
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(int)(_n)->_flags, LKPI_NAPI_FLAGS, _d)
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(unsigned int)ticks, _n, (uintmax_t)(_n)->state, \
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(int)(_n)->state, LKPI_NAPI_FLAGS, _d)
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#define NAPI_TRACE_TASK(_n, _p, _c) if (debug_napi & DNAPI_TRACE_TASK) \
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printf("NAPI_TRACE %s:%d %u %p (%#jx %b) pending %d count %d " \
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"rx_count %d\n", __func__, __LINE__, \
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(unsigned int)ticks, _n, (uintmax_t)(_n)->_flags, \
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(int)(_n)->_flags, LKPI_NAPI_FLAGS, _p, _c, (_n)->rx_count)
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(unsigned int)ticks, _n, (uintmax_t)(_n)->state, \
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(int)(_n)->state, LKPI_NAPI_FLAGS, _p, _c, (_n)->rx_count)
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#define NAPI_TODO() if (debug_napi & DNAPI_TODO) \
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printf("NAPI_TODO %s:%d %d\n", __func__, __LINE__, ticks)
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#define NAPI_IMPROVE() if (debug_napi & DNAPI_IMPROVE) \
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@ -118,7 +111,7 @@ linuxkpi_napi_schedule_prep(struct napi_struct *napi)
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/* Can can only update/return if all flags agree. */
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do {
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old = READ_ONCE(napi->_flags);
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old = READ_ONCE(napi->state);
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/* If we are stopping, cannot run again. */
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if ((old & BIT(LKPI_NAPI_FLAG_DISABLE_PENDING)) != 0) {
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@ -132,7 +125,7 @@ linuxkpi_napi_schedule_prep(struct napi_struct *napi)
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new |= BIT(LKPI_NAPI_FLAG_LOST_RACE_TRY_AGAIN);
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new |= BIT(LKPI_NAPI_FLAG_IS_SCHEDULED);
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} while (atomic_cmpset_acq_long(&napi->_flags, old, new) == 0);
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} while (atomic_cmpset_acq_long(&napi->state, old, new) == 0);
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NAPI_TRACE(napi);
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return ((old & BIT(LKPI_NAPI_FLAG_IS_SCHEDULED)) == 0);
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@ -157,14 +150,14 @@ lkpi___napi_schedule_dd(struct napi_struct *napi)
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goto again;
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/* Bandaid for now. */
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if (test_bit(LKPI_NAPI_FLAG_LOST_RACE_TRY_AGAIN, &napi->_flags))
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if (test_bit(LKPI_NAPI_FLAG_LOST_RACE_TRY_AGAIN, &napi->state))
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goto again;
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do {
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new = old = READ_ONCE(napi->_flags);
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new = old = READ_ONCE(napi->state);
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clear_bit(LKPI_NAPI_FLAG_LOST_RACE_TRY_AGAIN, &new);
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clear_bit(LKPI_NAPI_FLAG_IS_SCHEDULED, &new);
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} while (atomic_cmpset_acq_long(&napi->_flags, old, new) == 0);
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} while (atomic_cmpset_acq_long(&napi->state, old, new) == 0);
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NAPI_TRACE2D(napi, rc);
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}
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@ -175,9 +168,9 @@ linuxkpi___napi_schedule(struct napi_struct *napi)
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int rc;
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NAPI_TRACE(napi);
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if (test_bit(LKPI_NAPI_FLAG_SHUTDOWN, &napi->_flags)) {
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clear_bit(LKPI_NAPI_FLAG_LOST_RACE_TRY_AGAIN, &napi->_flags);
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clear_bit(LKPI_NAPI_FLAG_IS_SCHEDULED, &napi->_flags);
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if (test_bit(LKPI_NAPI_FLAG_SHUTDOWN, &napi->state)) {
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clear_bit(LKPI_NAPI_FLAG_LOST_RACE_TRY_AGAIN, &napi->state);
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clear_bit(LKPI_NAPI_FLAG_IS_SCHEDULED, &napi->state);
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NAPI_TRACE(napi);
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return;
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}
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@ -229,7 +222,7 @@ linuxkpi_napi_complete_done(struct napi_struct *napi, int ret)
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return (true);
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do {
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new = old = READ_ONCE(napi->_flags);
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new = old = READ_ONCE(napi->state);
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/*
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* If we lost a race before, we need to re-schedule.
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@ -238,7 +231,7 @@ linuxkpi_napi_complete_done(struct napi_struct *napi, int ret)
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if (!test_bit(LKPI_NAPI_FLAG_LOST_RACE_TRY_AGAIN, &old))
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clear_bit(LKPI_NAPI_FLAG_IS_SCHEDULED, &new);
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clear_bit(LKPI_NAPI_FLAG_LOST_RACE_TRY_AGAIN, &new);
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} while (atomic_cmpset_acq_long(&napi->_flags, old, new) == 0);
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} while (atomic_cmpset_acq_long(&napi->state, old, new) == 0);
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NAPI_TRACE(napi);
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@ -263,10 +256,10 @@ void
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linuxkpi_napi_disable(struct napi_struct *napi)
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{
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NAPI_TRACE(napi);
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set_bit(LKPI_NAPI_FLAG_DISABLE_PENDING, &napi->_flags);
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while (test_bit(LKPI_NAPI_FLAG_IS_SCHEDULED, &napi->_flags))
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set_bit(LKPI_NAPI_FLAG_DISABLE_PENDING, &napi->state);
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while (test_bit(LKPI_NAPI_FLAG_IS_SCHEDULED, &napi->state))
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pause_sbt("napidslp", SBT_1MS, 0, C_HARDCLOCK);
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clear_bit(LKPI_NAPI_FLAG_DISABLE_PENDING, &napi->_flags);
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clear_bit(LKPI_NAPI_FLAG_DISABLE_PENDING, &napi->state);
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}
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void
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@ -274,11 +267,11 @@ linuxkpi_napi_enable(struct napi_struct *napi)
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{
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NAPI_TRACE(napi);
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KASSERT(!test_bit(LKPI_NAPI_FLAG_IS_SCHEDULED, &napi->_flags),
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KASSERT(!test_bit(LKPI_NAPI_FLAG_IS_SCHEDULED, &napi->state),
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("%s: enabling napi %p already scheduled\n", __func__, napi));
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mb();
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/* Let us be scheduled. */
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clear_bit(LKPI_NAPI_FLAG_IS_SCHEDULED, &napi->_flags);
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clear_bit(LKPI_NAPI_FLAG_IS_SCHEDULED, &napi->state);
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}
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void
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@ -287,7 +280,7 @@ linuxkpi_napi_synchronize(struct napi_struct *napi)
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NAPI_TRACE(napi);
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#if defined(SMP)
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/* Check & sleep while a napi is scheduled. */
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while (test_bit(LKPI_NAPI_FLAG_IS_SCHEDULED, &napi->_flags))
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while (test_bit(LKPI_NAPI_FLAG_IS_SCHEDULED, &napi->state))
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pause_sbt("napisslp", SBT_1MS, 0, C_HARDCLOCK);
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#else
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mb();
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@ -350,7 +343,7 @@ linuxkpi_netif_napi_add(struct net_device *ndev, struct napi_struct *napi,
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NAPI_UNLOCK(ndev);
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/* Anything else to do on the ndev? */
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clear_bit(LKPI_NAPI_FLAG_SHUTDOWN, &napi->_flags);
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clear_bit(LKPI_NAPI_FLAG_SHUTDOWN, &napi->state);
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}
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static void
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@ -361,7 +354,7 @@ lkpi_netif_napi_del_locked(struct napi_struct *napi)
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ndev = napi->dev;
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NAPI_LOCK_ASSERT(ndev);
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set_bit(LKPI_NAPI_FLAG_SHUTDOWN, &napi->_flags);
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set_bit(LKPI_NAPI_FLAG_SHUTDOWN, &napi->state);
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TAILQ_REMOVE(&ndev->napi_head, napi, entry);
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while (taskqueue_cancel(ndev->napi_tq, &napi->napi_task, NULL) != 0)
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taskqueue_drain(ndev->napi_tq, &napi->napi_task);
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