io_uring/napi.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0

 #include "io_uring.h"
 #include "napi.h"

 #ifdef CONFIG_NET_RX_BUSY_POLL

 /* Timeout for cleanout of stale entries. */
 #define NAPI_TIMEOUT		(60 * SEC_CONVERSION)

 struct io_napi_entry {
 	unsigned int		napi_id;
 	struct list_head	list;

 	unsigned long		timeout;
 	struct hlist_node	node;

 	struct rcu_head		rcu;
 };

 static struct io_napi_entry *io_napi_hash_find(struct hlist_head *hash_list,
 					       unsigned int napi_id)
 {
 	struct io_napi_entry *e;

 	hlist_for_each_entry_rcu(e, hash_list, node) {
 		if (e->napi_id != napi_id)
 			continue;
 		return e;
 	}

 	return NULL;
 }

 static inline ktime_t net_to_ktime(unsigned long t)
 {
 	/* napi approximating usecs, reverse busy_loop_current_time */
 	return ns_to_ktime(t << 10);
 }

 void __io_napi_add(struct io_ring_ctx *ctx, struct socket *sock)
 {
 	struct hlist_head *hash_list;
 	unsigned int napi_id;
 	struct sock *sk;
 	struct io_napi_entry *e;

 	sk = sock->sk;
 	if (!sk)
 		return;

 	napi_id = READ_ONCE(sk->sk_napi_id);

 	/* Non-NAPI IDs can be rejected. */
 	if (napi_id < MIN_NAPI_ID)
 		return;

 	hash_list = &ctx->napi_ht[hash_min(napi_id, HASH_BITS(ctx->napi_ht))];

 	rcu_read_lock();
 	e = io_napi_hash_find(hash_list, napi_id);
 	if (e) {
 		e->timeout = jiffies + NAPI_TIMEOUT;
 		rcu_read_unlock();
 		return;
 	}
 	rcu_read_unlock();

 	e = kmalloc(sizeof(*e), GFP_NOWAIT);
 	if (!e)
 		return;

 	e->napi_id = napi_id;
 	e->timeout = jiffies + NAPI_TIMEOUT;

 	spin_lock(&ctx->napi_lock);
 	if (unlikely(io_napi_hash_find(hash_list, napi_id))) {
 		spin_unlock(&ctx->napi_lock);
 		kfree(e);
 		return;
 	}

 	hlist_add_tail_rcu(&e->node, hash_list);
 	list_add_tail(&e->list, &ctx->napi_list);
 	spin_unlock(&ctx->napi_lock);
 }

 static void __io_napi_remove_stale(struct io_ring_ctx *ctx)
 {
 	struct io_napi_entry *e;
 	unsigned int i;

 	spin_lock(&ctx->napi_lock);
 	hash_for_each(ctx->napi_ht, i, e, node) {
 		if (time_after(jiffies, e->timeout)) {
 			list_del(&e->list);
 			hash_del_rcu(&e->node);
 			kfree_rcu(e, rcu);
 		}
 	}
 	spin_unlock(&ctx->napi_lock);
 }

 static inline void io_napi_remove_stale(struct io_ring_ctx *ctx, bool is_stale)
 {
 	if (is_stale)
 		__io_napi_remove_stale(ctx);
 }

 static inline bool io_napi_busy_loop_timeout(ktime_t start_time,
 					     ktime_t bp)
 {
 	if (bp) {
 		ktime_t end_time = ktime_add(start_time, bp);
 		ktime_t now = net_to_ktime(busy_loop_current_time());

 		return ktime_after(now, end_time);
 	}

 	return true;
 }

 static bool io_napi_busy_loop_should_end(void *data,
 					 unsigned long start_time)
 {
 	struct io_wait_queue *iowq = data;

 	if (signal_pending(current))
 		return true;
 	if (io_should_wake(iowq) || io_has_work(iowq->ctx))
 		return true;
 	if (io_napi_busy_loop_timeout(net_to_ktime(start_time),
 				      iowq->napi_busy_poll_dt))
 		return true;

 	return false;
 }

 static bool __io_napi_do_busy_loop(struct io_ring_ctx *ctx,
 				   void *loop_end_arg)
 {
 	struct io_napi_entry *e;
 	bool (*loop_end)(void *, unsigned long) = NULL;
 	bool is_stale = false;

 	if (loop_end_arg)
 		loop_end = io_napi_busy_loop_should_end;

 	list_for_each_entry_rcu(e, &ctx->napi_list, list) {
 		napi_busy_loop_rcu(e->napi_id, loop_end, loop_end_arg,
 				   ctx->napi_prefer_busy_poll, BUSY_POLL_BUDGET);

 		if (time_after(jiffies, e->timeout))
 			is_stale = true;
 	}

 	return is_stale;
 }

 static void io_napi_blocking_busy_loop(struct io_ring_ctx *ctx,
 				       struct io_wait_queue *iowq)
 {
 	unsigned long start_time = busy_loop_current_time();
 	void *loop_end_arg = NULL;
 	bool is_stale = false;

 	/* Singular lists use a different napi loop end check function and are
 	 * only executed once.
 	 */
 	if (list_is_singular(&ctx->napi_list))
 		loop_end_arg = iowq;

 	rcu_read_lock();
 	do {
 		is_stale = __io_napi_do_busy_loop(ctx, loop_end_arg);
 	} while (!io_napi_busy_loop_should_end(iowq, start_time) && !loop_end_arg);
 	rcu_read_unlock();

 	io_napi_remove_stale(ctx, is_stale);
 }

 /*
  * io_napi_init() - Init napi settings
  * @ctx: pointer to io-uring context structure
  *
  * Init napi settings in the io-uring context.
  */
 void io_napi_init(struct io_ring_ctx *ctx)
 {
 	u64 sys_dt = READ_ONCE(sysctl_net_busy_poll) * NSEC_PER_USEC;

 	INIT_LIST_HEAD(&ctx->napi_list);
 	spin_lock_init(&ctx->napi_lock);
 	ctx->napi_prefer_busy_poll = false;
 	ctx->napi_busy_poll_dt = ns_to_ktime(sys_dt);
 }

 /*
  * io_napi_free() - Deallocate napi
  * @ctx: pointer to io-uring context structure
  *
  * Free the napi list and the hash table in the io-uring context.
  */
 void io_napi_free(struct io_ring_ctx *ctx)
 {
 	struct io_napi_entry *e;
 	unsigned int i;

 	spin_lock(&ctx->napi_lock);
 	hash_for_each(ctx->napi_ht, i, e, node) {
 		hash_del_rcu(&e->node);
 		kfree_rcu(e, rcu);
 	}
 	spin_unlock(&ctx->napi_lock);
 }

 /*
  * io_napi_register() - Register napi with io-uring
  * @ctx: pointer to io-uring context structure
  * @arg: pointer to io_uring_napi structure
  *
  * Register napi in the io-uring context.
  */
 int io_register_napi(struct io_ring_ctx *ctx, void __user *arg)
 {
 	const struct io_uring_napi curr = {
 		.busy_poll_to 	  = ktime_to_us(ctx->napi_busy_poll_dt),
 		.prefer_busy_poll = ctx->napi_prefer_busy_poll
 	};
 	struct io_uring_napi napi;

 	if (ctx->flags & IORING_SETUP_IOPOLL)
 		return -EINVAL;
 	if (copy_from_user(&napi, arg, sizeof(napi)))
 		return -EFAULT;
 	if (napi.pad[0] || napi.pad[1] || napi.pad[2] || napi.resv)
 		return -EINVAL;

 	if (copy_to_user(arg, &curr, sizeof(curr)))
 		return -EFAULT;

 	WRITE_ONCE(ctx->napi_busy_poll_dt, napi.busy_poll_to * NSEC_PER_USEC);
 	WRITE_ONCE(ctx->napi_prefer_busy_poll, !!napi.prefer_busy_poll);
 	WRITE_ONCE(ctx->napi_enabled, true);
 	return 0;
 }

 /*
  * io_napi_unregister() - Unregister napi with io-uring
  * @ctx: pointer to io-uring context structure
  * @arg: pointer to io_uring_napi structure
  *
  * Unregister napi. If arg has been specified copy the busy poll timeout and
  * prefer busy poll setting to the passed in structure.
  */
 int io_unregister_napi(struct io_ring_ctx *ctx, void __user *arg)
 {
 	const struct io_uring_napi curr = {
 		.busy_poll_to 	  = ktime_to_us(ctx->napi_busy_poll_dt),
 		.prefer_busy_poll = ctx->napi_prefer_busy_poll
 	};

 	if (arg && copy_to_user(arg, &curr, sizeof(curr)))
 		return -EFAULT;

 	WRITE_ONCE(ctx->napi_busy_poll_dt, 0);
 	WRITE_ONCE(ctx->napi_prefer_busy_poll, false);
 	WRITE_ONCE(ctx->napi_enabled, false);
 	return 0;
 }

 /*
  * __io_napi_busy_loop() - execute busy poll loop
  * @ctx: pointer to io-uring context structure
  * @iowq: pointer to io wait queue
  *
  * Execute the busy poll loop and merge the spliced off list.
  */
 void __io_napi_busy_loop(struct io_ring_ctx *ctx, struct io_wait_queue *iowq)
 {
 	if (ctx->flags & IORING_SETUP_SQPOLL)
 		return;

 	iowq->napi_busy_poll_dt = READ_ONCE(ctx->napi_busy_poll_dt);
 	if (iowq->timeout != KTIME_MAX) {
 		ktime_t dt = ktime_sub(iowq->timeout, io_get_time(ctx));

 		iowq->napi_busy_poll_dt = min_t(u64, iowq->napi_busy_poll_dt, dt);
 	}

 	iowq->napi_prefer_busy_poll = READ_ONCE(ctx->napi_prefer_busy_poll);
 	io_napi_blocking_busy_loop(ctx, iowq);
 }

 /*
  * io_napi_sqpoll_busy_poll() - busy poll loop for sqpoll
  * @ctx: pointer to io-uring context structure
  *
  * Splice of the napi list and execute the napi busy poll loop.
  */
 int io_napi_sqpoll_busy_poll(struct io_ring_ctx *ctx)
 {
 	bool is_stale = false;

 	if (!READ_ONCE(ctx->napi_busy_poll_dt))
 		return 0;
 	if (list_empty_careful(&ctx->napi_list))
 		return 0;

 	rcu_read_lock();
 	is_stale = __io_napi_do_busy_loop(ctx, NULL);
 	rcu_read_unlock();

 	io_napi_remove_stale(ctx, is_stale);
 	return 1;
 }

 #endif
	// SPDX-License-Identifier: GPL-2.0

	#include "io_uring.h"
	#include "napi.h"

	#ifdef CONFIG_NET_RX_BUSY_POLL

	/* Timeout for cleanout of stale entries. */
	#define NAPI_TIMEOUT (60 * SEC_CONVERSION)

	struct io_napi_entry {
	unsigned int napi_id;
	struct list_head list;

	unsigned long timeout;
	struct hlist_node node;

	struct rcu_head rcu;
	};

	static struct io_napi_entry io_napi_hash_find(struct hlist_head hash_list,
	unsigned int napi_id)
	{
	struct io_napi_entry *e;

	hlist_for_each_entry_rcu(e, hash_list, node) {
	if (e->napi_id != napi_id)
	continue;
	return e;
	}

	return NULL;
	}

	static inline ktime_t net_to_ktime(unsigned long t)
	{
	/* napi approximating usecs, reverse busy_loop_current_time */
	return ns_to_ktime(t << 10);
	}

	void __io_napi_add(struct io_ring_ctx ctx, struct socket sock)
	{
	struct hlist_head *hash_list;
	unsigned int napi_id;
	struct sock *sk;
	struct io_napi_entry *e;

	sk = sock->sk;
	if (!sk)
	return;

	napi_id = READ_ONCE(sk->sk_napi_id);

	/* Non-NAPI IDs can be rejected. */
	if (napi_id < MIN_NAPI_ID)
	return;

	hash_list = &ctx->napi_ht[hash_min(napi_id, HASH_BITS(ctx->napi_ht))];

	rcu_read_lock();
	e = io_napi_hash_find(hash_list, napi_id);
	if (e) {
	e->timeout = jiffies + NAPI_TIMEOUT;
	rcu_read_unlock();
	return;
	}
	rcu_read_unlock();

	e = kmalloc(sizeof(*e), GFP_NOWAIT);
	if (!e)
	return;

	e->napi_id = napi_id;
	e->timeout = jiffies + NAPI_TIMEOUT;

	spin_lock(&ctx->napi_lock);
	if (unlikely(io_napi_hash_find(hash_list, napi_id))) {
	spin_unlock(&ctx->napi_lock);
	kfree(e);
	return;
	}

	hlist_add_tail_rcu(&e->node, hash_list);
	list_add_tail(&e->list, &ctx->napi_list);
	spin_unlock(&ctx->napi_lock);
	}

	static void __io_napi_remove_stale(struct io_ring_ctx *ctx)
	{
	struct io_napi_entry *e;
	unsigned int i;

	spin_lock(&ctx->napi_lock);
	hash_for_each(ctx->napi_ht, i, e, node) {
	if (time_after(jiffies, e->timeout)) {
	list_del(&e->list);
	hash_del_rcu(&e->node);
	kfree_rcu(e, rcu);
	}
	}
	spin_unlock(&ctx->napi_lock);
	}

	static inline void io_napi_remove_stale(struct io_ring_ctx *ctx, bool is_stale)
	{
	if (is_stale)
	__io_napi_remove_stale(ctx);
	}

	static inline bool io_napi_busy_loop_timeout(ktime_t start_time,
	ktime_t bp)
	{
	if (bp) {
	ktime_t end_time = ktime_add(start_time, bp);
	ktime_t now = net_to_ktime(busy_loop_current_time());

	return ktime_after(now, end_time);
	}

	return true;
	}

	static bool io_napi_busy_loop_should_end(void *data,
	unsigned long start_time)
	{
	struct io_wait_queue *iowq = data;

	if (signal_pending(current))
	return true;
	if (io_should_wake(iowq) \|\| io_has_work(iowq->ctx))
	return true;
	if (io_napi_busy_loop_timeout(net_to_ktime(start_time),
	iowq->napi_busy_poll_dt))
	return true;

	return false;
	}

	static bool __io_napi_do_busy_loop(struct io_ring_ctx *ctx,
	void *loop_end_arg)
	{
	struct io_napi_entry *e;
	bool (loop_end)(void , unsigned long) = NULL;
	bool is_stale = false;

	if (loop_end_arg)
	loop_end = io_napi_busy_loop_should_end;

	list_for_each_entry_rcu(e, &ctx->napi_list, list) {
	napi_busy_loop_rcu(e->napi_id, loop_end, loop_end_arg,
	ctx->napi_prefer_busy_poll, BUSY_POLL_BUDGET);

	if (time_after(jiffies, e->timeout))
	is_stale = true;
	}

	return is_stale;
	}

	static void io_napi_blocking_busy_loop(struct io_ring_ctx *ctx,
	struct io_wait_queue *iowq)
	{
	unsigned long start_time = busy_loop_current_time();
	void *loop_end_arg = NULL;
	bool is_stale = false;

	/* Singular lists use a different napi loop end check function and are
	* only executed once.
	*/
	if (list_is_singular(&ctx->napi_list))
	loop_end_arg = iowq;

	rcu_read_lock();
	do {
	is_stale = __io_napi_do_busy_loop(ctx, loop_end_arg);
	} while (!io_napi_busy_loop_should_end(iowq, start_time) && !loop_end_arg);
	rcu_read_unlock();

	io_napi_remove_stale(ctx, is_stale);
	}

	/*
	* io_napi_init() - Init napi settings
	* @ctx: pointer to io-uring context structure
	*
	* Init napi settings in the io-uring context.
	*/
	void io_napi_init(struct io_ring_ctx *ctx)
	{
	u64 sys_dt = READ_ONCE(sysctl_net_busy_poll) * NSEC_PER_USEC;

	INIT_LIST_HEAD(&ctx->napi_list);
	spin_lock_init(&ctx->napi_lock);
	ctx->napi_prefer_busy_poll = false;
	ctx->napi_busy_poll_dt = ns_to_ktime(sys_dt);
	}

	/*
	* io_napi_free() - Deallocate napi
	* @ctx: pointer to io-uring context structure
	*
	* Free the napi list and the hash table in the io-uring context.
	*/
	void io_napi_free(struct io_ring_ctx *ctx)
	{
	struct io_napi_entry *e;
	unsigned int i;

	spin_lock(&ctx->napi_lock);
	hash_for_each(ctx->napi_ht, i, e, node) {
	hash_del_rcu(&e->node);
	kfree_rcu(e, rcu);
	}
	spin_unlock(&ctx->napi_lock);
	}

	/*
	* io_napi_register() - Register napi with io-uring
	* @ctx: pointer to io-uring context structure
	* @arg: pointer to io_uring_napi structure
	*
	* Register napi in the io-uring context.
	*/
	int io_register_napi(struct io_ring_ctx ctx, void __user arg)
	{
	const struct io_uring_napi curr = {
	.busy_poll_to = ktime_to_us(ctx->napi_busy_poll_dt),
	.prefer_busy_poll = ctx->napi_prefer_busy_poll
	};
	struct io_uring_napi napi;

	if (ctx->flags & IORING_SETUP_IOPOLL)
	return -EINVAL;
	if (copy_from_user(&napi, arg, sizeof(napi)))
	return -EFAULT;
	if (napi.pad[0] \|\| napi.pad[1] \|\| napi.pad[2] \|\| napi.resv)
	return -EINVAL;

	if (copy_to_user(arg, &curr, sizeof(curr)))
	return -EFAULT;

	WRITE_ONCE(ctx->napi_busy_poll_dt, napi.busy_poll_to * NSEC_PER_USEC);
	WRITE_ONCE(ctx->napi_prefer_busy_poll, !!napi.prefer_busy_poll);
	WRITE_ONCE(ctx->napi_enabled, true);
	return 0;
	}

	/*
	* io_napi_unregister() - Unregister napi with io-uring
	* @ctx: pointer to io-uring context structure
	* @arg: pointer to io_uring_napi structure
	*
	* Unregister napi. If arg has been specified copy the busy poll timeout and
	* prefer busy poll setting to the passed in structure.
	*/
	int io_unregister_napi(struct io_ring_ctx ctx, void __user arg)
	{
	const struct io_uring_napi curr = {
	.busy_poll_to = ktime_to_us(ctx->napi_busy_poll_dt),
	.prefer_busy_poll = ctx->napi_prefer_busy_poll
	};

	if (arg && copy_to_user(arg, &curr, sizeof(curr)))
	return -EFAULT;

	WRITE_ONCE(ctx->napi_busy_poll_dt, 0);
	WRITE_ONCE(ctx->napi_prefer_busy_poll, false);
	WRITE_ONCE(ctx->napi_enabled, false);
	return 0;
	}

	/*
	* __io_napi_busy_loop() - execute busy poll loop
	* @ctx: pointer to io-uring context structure
	* @iowq: pointer to io wait queue
	*
	* Execute the busy poll loop and merge the spliced off list.
	*/
	void __io_napi_busy_loop(struct io_ring_ctx ctx, struct io_wait_queue iowq)
	{
	if (ctx->flags & IORING_SETUP_SQPOLL)
	return;

	iowq->napi_busy_poll_dt = READ_ONCE(ctx->napi_busy_poll_dt);
	if (iowq->timeout != KTIME_MAX) {
	ktime_t dt = ktime_sub(iowq->timeout, io_get_time(ctx));

	iowq->napi_busy_poll_dt = min_t(u64, iowq->napi_busy_poll_dt, dt);
	}

	iowq->napi_prefer_busy_poll = READ_ONCE(ctx->napi_prefer_busy_poll);
	io_napi_blocking_busy_loop(ctx, iowq);
	}

	/*
	* io_napi_sqpoll_busy_poll() - busy poll loop for sqpoll
	* @ctx: pointer to io-uring context structure
	*
	* Splice of the napi list and execute the napi busy poll loop.
	*/
	int io_napi_sqpoll_busy_poll(struct io_ring_ctx *ctx)
	{
	bool is_stale = false;

	if (!READ_ONCE(ctx->napi_busy_poll_dt))
	return 0;
	if (list_empty_careful(&ctx->napi_list))
	return 0;

	rcu_read_lock();
	is_stale = __io_napi_do_busy_loop(ctx, NULL);
	rcu_read_unlock();

	io_napi_remove_stale(ctx, is_stale);
	return 1;
	}

	#endif