swh:1:snp:0424f14fb59df2ee63d8659da5115ce9de06a349
Tip revision: e8b0ccb2a787fb43f8091a1eaef9c28a79b00002 authored by Linus Torvalds on 05 April 2024, 17:05:42 UTC
Merge tag '9p-for-6.9-rc3' of https://github.com/martinetd/linux
Merge tag '9p-for-6.9-rc3' of https://github.com/martinetd/linux
Tip revision: e8b0ccb
napi.c
// 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;
e->timeout = jiffies + NAPI_TIMEOUT;
return e;
}
return NULL;
}
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(unsigned long start_time,
unsigned long bp_usec)
{
if (bp_usec) {
unsigned long end_time = start_time + bp_usec;
unsigned long now = busy_loop_current_time();
return time_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(start_time, iowq->napi_busy_poll_to))
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)
{
INIT_LIST_HEAD(&ctx->napi_list);
spin_lock_init(&ctx->napi_lock);
ctx->napi_prefer_busy_poll = false;
ctx->napi_busy_poll_to = READ_ONCE(sysctl_net_busy_poll);
}
/*
* 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;
LIST_HEAD(napi_list);
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 = ctx->napi_busy_poll_to,
.prefer_busy_poll = ctx->napi_prefer_busy_poll
};
struct io_uring_napi napi;
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_to, napi.busy_poll_to);
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 = ctx->napi_busy_poll_to,
.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_to, 0);
WRITE_ONCE(ctx->napi_prefer_busy_poll, false);
WRITE_ONCE(ctx->napi_enabled, false);
return 0;
}
/*
* __io_napi_adjust_timeout() - Add napi id to the busy poll list
* @ctx: pointer to io-uring context structure
* @iowq: pointer to io wait queue
* @ts: pointer to timespec or NULL
*
* Adjust the busy loop timeout according to timespec and busy poll timeout.
*/
void __io_napi_adjust_timeout(struct io_ring_ctx *ctx, struct io_wait_queue *iowq,
struct timespec64 *ts)
{
unsigned int poll_to = READ_ONCE(ctx->napi_busy_poll_to);
if (ts) {
struct timespec64 poll_to_ts = ns_to_timespec64(1000 * (s64)poll_to);
if (timespec64_compare(ts, &poll_to_ts) > 0) {
*ts = timespec64_sub(*ts, poll_to_ts);
} else {
u64 to = timespec64_to_ns(ts);
do_div(to, 1000);
ts->tv_sec = 0;
ts->tv_nsec = 0;
}
}
iowq->napi_busy_poll_to = poll_to;
}
/*
* __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)
{
iowq->napi_prefer_busy_poll = READ_ONCE(ctx->napi_prefer_busy_poll);
if (!(ctx->flags & IORING_SETUP_SQPOLL) && ctx->napi_enabled)
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)
{
LIST_HEAD(napi_list);
bool is_stale = false;
if (!READ_ONCE(ctx->napi_busy_poll_to))
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