From 13d381b440ed84ec4cc92975de035efb1a9e5f7e Mon Sep 17 00:00:00 2001 From: Stefan Roesch Date: Tue, 6 Feb 2024 09:30:03 -0700 Subject: net: split off __napi_busy_poll from napi_busy_poll This splits off the key part of the napi_busy_poll function into its own function, __napi_busy_poll, and changes the prefer_busy_poll bool to be flag based to allow passing in more flags in the future. This is done in preparation for an additional napi_busy_poll() function, that doesn't take the rcu_read_lock(). The new function is introduced in the next patch. Signed-off-by: Stefan Roesch Link: https://lore.kernel.org/r/20230608163839.2891748-2-shr@devkernel.io Signed-off-by: Jens Axboe Signed-off-by: Jakub Kicinski --- net/core/dev.c | 42 ++++++++++++++++++++++++++++-------------- 1 file changed, 28 insertions(+), 14 deletions(-) (limited to 'net') diff --git a/net/core/dev.c b/net/core/dev.c index cb2dab0feee0..1eaed657f2c2 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6177,8 +6177,12 @@ static void __busy_poll_stop(struct napi_struct *napi, bool skip_schedule) clear_bit(NAPI_STATE_SCHED, &napi->state); } -static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock, bool prefer_busy_poll, - u16 budget) +enum { + NAPI_F_PREFER_BUSY_POLL = 1, +}; + +static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock, + unsigned flags, u16 budget) { bool skip_schedule = false; unsigned long timeout; @@ -6198,7 +6202,7 @@ static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock, bool local_bh_disable(); - if (prefer_busy_poll) { + if (flags & NAPI_F_PREFER_BUSY_POLL) { napi->defer_hard_irqs_count = READ_ONCE(napi->dev->napi_defer_hard_irqs); timeout = READ_ONCE(napi->dev->gro_flush_timeout); if (napi->defer_hard_irqs_count && timeout) { @@ -6222,23 +6226,23 @@ static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock, bool local_bh_enable(); } -void napi_busy_loop(unsigned int napi_id, - bool (*loop_end)(void *, unsigned long), - void *loop_end_arg, bool prefer_busy_poll, u16 budget) +static void __napi_busy_loop(unsigned int napi_id, + bool (*loop_end)(void *, unsigned long), + void *loop_end_arg, unsigned flags, u16 budget) { unsigned long start_time = loop_end ? busy_loop_current_time() : 0; int (*napi_poll)(struct napi_struct *napi, int budget); void *have_poll_lock = NULL; struct napi_struct *napi; + WARN_ON_ONCE(!rcu_read_lock_held()); + restart: napi_poll = NULL; - rcu_read_lock(); - napi = napi_by_id(napi_id); if (!napi) - goto out; + return; if (!IS_ENABLED(CONFIG_PREEMPT_RT)) preempt_disable(); @@ -6254,14 +6258,14 @@ restart: */ if (val & (NAPIF_STATE_DISABLE | NAPIF_STATE_SCHED | NAPIF_STATE_IN_BUSY_POLL)) { - if (prefer_busy_poll) + if (flags & NAPI_F_PREFER_BUSY_POLL) set_bit(NAPI_STATE_PREFER_BUSY_POLL, &napi->state); goto count; } if (cmpxchg(&napi->state, val, val | NAPIF_STATE_IN_BUSY_POLL | NAPIF_STATE_SCHED) != val) { - if (prefer_busy_poll) + if (flags & NAPI_F_PREFER_BUSY_POLL) set_bit(NAPI_STATE_PREFER_BUSY_POLL, &napi->state); goto count; } @@ -6282,11 +6286,12 @@ count: if (unlikely(need_resched())) { if (napi_poll) - busy_poll_stop(napi, have_poll_lock, prefer_busy_poll, budget); + busy_poll_stop(napi, have_poll_lock, flags, budget); if (!IS_ENABLED(CONFIG_PREEMPT_RT)) preempt_enable(); rcu_read_unlock(); cond_resched(); + rcu_read_lock(); if (loop_end(loop_end_arg, start_time)) return; goto restart; @@ -6294,10 +6299,19 @@ count: cpu_relax(); } if (napi_poll) - busy_poll_stop(napi, have_poll_lock, prefer_busy_poll, budget); + busy_poll_stop(napi, have_poll_lock, flags, budget); if (!IS_ENABLED(CONFIG_PREEMPT_RT)) preempt_enable(); -out: +} + +void napi_busy_loop(unsigned int napi_id, + bool (*loop_end)(void *, unsigned long), + void *loop_end_arg, bool prefer_busy_poll, u16 budget) +{ + unsigned flags = prefer_busy_poll ? NAPI_F_PREFER_BUSY_POLL : 0; + + rcu_read_lock(); + __napi_busy_loop(napi_id, loop_end, loop_end_arg, flags, budget); rcu_read_unlock(); } EXPORT_SYMBOL(napi_busy_loop); -- cgit v1.2.3 From b4e8ae5c8c41355791a99fdf2fcac16deace1e79 Mon Sep 17 00:00:00 2001 From: Stefan Roesch Date: Tue, 6 Feb 2024 09:30:04 -0700 Subject: net: add napi_busy_loop_rcu() This adds the napi_busy_loop_rcu() function. This function assumes that the calling function is already holding the rcu read lock and napi_busy_loop() does not need to take the rcu read lock. Add a NAPI_F_NO_SCHED flag, which tells __napi_busy_loop() to abort if we need to reschedule rather than drop the RCU read lock and reschedule. Signed-off-by: Stefan Roesch Link: https://lore.kernel.org/r/20230608163839.2891748-3-shr@devkernel.io Signed-off-by: Jens Axboe Signed-off-by: Jakub Kicinski --- include/net/busy_poll.h | 4 ++++ net/core/dev.c | 15 +++++++++++++++ 2 files changed, 19 insertions(+) (limited to 'net') diff --git a/include/net/busy_poll.h b/include/net/busy_poll.h index 4dabeb6c76d3..9b09acac538e 100644 --- a/include/net/busy_poll.h +++ b/include/net/busy_poll.h @@ -48,6 +48,10 @@ void napi_busy_loop(unsigned int napi_id, bool (*loop_end)(void *, unsigned long), void *loop_end_arg, bool prefer_busy_poll, u16 budget); +void napi_busy_loop_rcu(unsigned int napi_id, + bool (*loop_end)(void *, unsigned long), + void *loop_end_arg, bool prefer_busy_poll, u16 budget); + #else /* CONFIG_NET_RX_BUSY_POLL */ static inline unsigned long net_busy_loop_on(void) { diff --git a/net/core/dev.c b/net/core/dev.c index 1eaed657f2c2..ffa394f3e796 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6179,6 +6179,7 @@ static void __busy_poll_stop(struct napi_struct *napi, bool skip_schedule) enum { NAPI_F_PREFER_BUSY_POLL = 1, + NAPI_F_END_ON_RESCHED = 2, }; static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock, @@ -6285,6 +6286,8 @@ count: break; if (unlikely(need_resched())) { + if (flags & NAPI_F_END_ON_RESCHED) + break; if (napi_poll) busy_poll_stop(napi, have_poll_lock, flags, budget); if (!IS_ENABLED(CONFIG_PREEMPT_RT)) @@ -6304,6 +6307,18 @@ count: preempt_enable(); } +void napi_busy_loop_rcu(unsigned int napi_id, + bool (*loop_end)(void *, unsigned long), + void *loop_end_arg, bool prefer_busy_poll, u16 budget) +{ + unsigned flags = NAPI_F_END_ON_RESCHED; + + if (prefer_busy_poll) + flags |= NAPI_F_PREFER_BUSY_POLL; + + __napi_busy_loop(napi_id, loop_end, loop_end_arg, flags, budget); +} + void napi_busy_loop(unsigned int napi_id, bool (*loop_end)(void *, unsigned long), void *loop_end_arg, bool prefer_busy_poll, u16 budget) -- cgit v1.2.3