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io_uring: Add support for napi_busy_poll
The sqpoll thread can be used for performing the napi busy poll in a similar way that it does io polling for file systems supporting direct access bypassing the page cache. The other way that io_uring can be used for napi busy poll is by calling io_uring_enter() to get events. If the user specify a timeout value, it is distributed between polling and sleeping by using the systemwide setting /proc/sys/net/core/busy_poll. The changes have been tested with this program: https://github.com/lano1106/io_uring_udp_ping and the result is: Without sqpoll: NAPI busy loop disabled: rtt min/avg/max/mdev = 40.631/42.050/58.667/1.547 us NAPI busy loop enabled: rtt min/avg/max/mdev = 30.619/31.753/61.433/1.456 us With sqpoll: NAPI busy loop disabled: rtt min/avg/max/mdev = 42.087/44.438/59.508/1.533 us NAPI busy loop enabled: rtt min/avg/max/mdev = 35.779/37.347/52.201/0.924 us Co-developed-by: Hao Xu <haoxu@linux.alibaba.com> Signed-off-by: Hao Xu <haoxu@linux.alibaba.com> Signed-off-by: Olivier Langlois <olivier@trillion01.com> Link: https://lore.kernel.org/r/810bd9408ffc510ff08269e78dca9df4af0b9e4e.1646777484.git.olivier@trillion01.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Olivier Langlois
Jens Axboe
parent
950e79dd73
commit
adc8682ec6
1 changed files with 231 additions and 1 deletions
232
fs/io_uring.c
232
fs/io_uring.c
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@ -63,6 +63,7 @@
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#include <net/sock.h>
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#include <net/af_unix.h>
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#include <net/scm.h>
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#include <net/busy_poll.h>
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#include <linux/anon_inodes.h>
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#include <linux/sched/mm.h>
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#include <linux/uaccess.h>
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@ -401,6 +402,11 @@ struct io_ring_ctx {
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struct list_head sqd_list;
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unsigned long check_cq_overflow;
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#ifdef CONFIG_NET_RX_BUSY_POLL
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/* used to track busy poll napi_id */
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struct list_head napi_list;
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spinlock_t napi_lock; /* napi_list lock */
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#endif
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struct {
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unsigned cached_cq_tail;
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@ -1513,6 +1519,10 @@ static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
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INIT_WQ_LIST(&ctx->locked_free_list);
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INIT_DELAYED_WORK(&ctx->fallback_work, io_fallback_req_func);
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INIT_WQ_LIST(&ctx->submit_state.compl_reqs);
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#ifdef CONFIG_NET_RX_BUSY_POLL
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INIT_LIST_HEAD(&ctx->napi_list);
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spin_lock_init(&ctx->napi_lock);
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#endif
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return ctx;
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err:
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kfree(ctx->dummy_ubuf);
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@ -5581,6 +5591,108 @@ IO_NETOP_FN(send);
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IO_NETOP_FN(recv);
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#endif /* CONFIG_NET */
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#ifdef CONFIG_NET_RX_BUSY_POLL
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#define NAPI_TIMEOUT (60 * SEC_CONVERSION)
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struct napi_entry {
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struct list_head list;
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unsigned int napi_id;
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unsigned long timeout;
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};
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/*
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* Add busy poll NAPI ID from sk.
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*/
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static void io_add_napi(struct file *file, struct io_ring_ctx *ctx)
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{
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unsigned int napi_id;
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struct socket *sock;
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struct sock *sk;
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struct napi_entry *ne;
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if (!net_busy_loop_on())
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return;
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sock = sock_from_file(file);
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if (!sock)
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return;
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sk = sock->sk;
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if (!sk)
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return;
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napi_id = READ_ONCE(sk->sk_napi_id);
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/* Non-NAPI IDs can be rejected */
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if (napi_id < MIN_NAPI_ID)
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return;
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spin_lock(&ctx->napi_lock);
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list_for_each_entry(ne, &ctx->napi_list, list) {
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if (ne->napi_id == napi_id) {
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ne->timeout = jiffies + NAPI_TIMEOUT;
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goto out;
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}
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}
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ne = kmalloc(sizeof(*ne), GFP_NOWAIT);
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if (!ne)
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goto out;
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ne->napi_id = napi_id;
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ne->timeout = jiffies + NAPI_TIMEOUT;
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list_add_tail(&ne->list, &ctx->napi_list);
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out:
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spin_unlock(&ctx->napi_lock);
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}
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static inline void io_check_napi_entry_timeout(struct napi_entry *ne)
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{
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if (time_after(jiffies, ne->timeout)) {
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list_del(&ne->list);
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kfree(ne);
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}
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}
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/*
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* Busy poll if globally on and supporting sockets found
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*/
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static bool io_napi_busy_loop(struct list_head *napi_list)
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{
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struct napi_entry *ne, *n;
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list_for_each_entry_safe(ne, n, napi_list, list) {
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napi_busy_loop(ne->napi_id, NULL, NULL, true,
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BUSY_POLL_BUDGET);
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io_check_napi_entry_timeout(ne);
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}
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return !list_empty(napi_list);
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}
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static void io_free_napi_list(struct io_ring_ctx *ctx)
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{
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spin_lock(&ctx->napi_lock);
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while (!list_empty(&ctx->napi_list)) {
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struct napi_entry *ne =
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list_first_entry(&ctx->napi_list, struct napi_entry,
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list);
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list_del(&ne->list);
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kfree(ne);
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}
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spin_unlock(&ctx->napi_lock);
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}
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#else
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static inline void io_add_napi(struct file *file, struct io_ring_ctx *ctx)
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{
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}
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static inline void io_free_napi_list(struct io_ring_ctx *ctx)
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{
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}
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#endif /* CONFIG_NET_RX_BUSY_POLL */
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struct io_poll_table {
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struct poll_table_struct pt;
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struct io_kiocb *req;
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@ -5727,6 +5839,7 @@ static int io_poll_check_events(struct io_kiocb *req)
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if (unlikely(!filled))
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return -ECANCELED;
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io_cqring_ev_posted(ctx);
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io_add_napi(req->file, ctx);
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} else if (req->result) {
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return 0;
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}
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@ -5959,6 +6072,7 @@ static int __io_arm_poll_handler(struct io_kiocb *req,
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__io_poll_execute(req, mask);
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return 0;
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}
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io_add_napi(req->file, req->ctx);
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/*
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* Release ownership. If someone tried to queue a tw while it was
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@ -7706,7 +7820,13 @@ static int __io_sq_thread(struct io_ring_ctx *ctx, bool cap_entries)
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!(ctx->flags & IORING_SETUP_R_DISABLED))
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ret = io_submit_sqes(ctx, to_submit);
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mutex_unlock(&ctx->uring_lock);
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#ifdef CONFIG_NET_RX_BUSY_POLL
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spin_lock(&ctx->napi_lock);
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if (!list_empty(&ctx->napi_list) &&
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io_napi_busy_loop(&ctx->napi_list))
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++ret;
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spin_unlock(&ctx->napi_lock);
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#endif
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if (to_submit && wq_has_sleeper(&ctx->sqo_sq_wait))
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wake_up(&ctx->sqo_sq_wait);
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if (creds)
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@ -7837,6 +7957,9 @@ struct io_wait_queue {
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struct io_ring_ctx *ctx;
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unsigned cq_tail;
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unsigned nr_timeouts;
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#ifdef CONFIG_NET_RX_BUSY_POLL
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unsigned busy_poll_to;
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#endif
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};
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static inline bool io_should_wake(struct io_wait_queue *iowq)
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@ -7898,6 +8021,87 @@ static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
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return 1;
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}
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#ifdef CONFIG_NET_RX_BUSY_POLL
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static void io_adjust_busy_loop_timeout(struct timespec64 *ts,
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struct io_wait_queue *iowq)
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{
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unsigned busy_poll_to = READ_ONCE(sysctl_net_busy_poll);
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struct timespec64 pollto = ns_to_timespec64(1000 * (s64)busy_poll_to);
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if (timespec64_compare(ts, &pollto) > 0) {
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*ts = timespec64_sub(*ts, pollto);
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iowq->busy_poll_to = busy_poll_to;
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} else {
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u64 to = timespec64_to_ns(ts);
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do_div(to, 1000);
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iowq->busy_poll_to = to;
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ts->tv_sec = 0;
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ts->tv_nsec = 0;
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}
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}
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static inline bool io_busy_loop_timeout(unsigned long start_time,
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unsigned long bp_usec)
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{
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if (bp_usec) {
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unsigned long end_time = start_time + bp_usec;
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unsigned long now = busy_loop_current_time();
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return time_after(now, end_time);
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}
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return true;
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}
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static bool io_busy_loop_end(void *p, unsigned long start_time)
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{
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struct io_wait_queue *iowq = p;
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return signal_pending(current) ||
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io_should_wake(iowq) ||
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io_busy_loop_timeout(start_time, iowq->busy_poll_to);
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}
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static void io_blocking_napi_busy_loop(struct list_head *napi_list,
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struct io_wait_queue *iowq)
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{
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unsigned long start_time =
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list_is_singular(napi_list) ? 0 :
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busy_loop_current_time();
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do {
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if (list_is_singular(napi_list)) {
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struct napi_entry *ne =
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list_first_entry(napi_list,
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struct napi_entry, list);
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napi_busy_loop(ne->napi_id, io_busy_loop_end, iowq,
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true, BUSY_POLL_BUDGET);
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io_check_napi_entry_timeout(ne);
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break;
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}
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} while (io_napi_busy_loop(napi_list) &&
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!io_busy_loop_end(iowq, start_time));
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}
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static void io_putback_napi_list(struct io_ring_ctx *ctx,
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struct list_head *napi_list)
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{
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struct napi_entry *cne, *lne;
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spin_lock(&ctx->napi_lock);
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list_for_each_entry(cne, &ctx->napi_list, list)
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list_for_each_entry(lne, napi_list, list)
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if (cne->napi_id == lne->napi_id) {
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list_del(&lne->list);
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kfree(lne);
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break;
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}
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list_splice(napi_list, &ctx->napi_list);
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spin_unlock(&ctx->napi_lock);
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}
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#endif /* CONFIG_NET_RX_BUSY_POLL */
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/*
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* Wait until events become available, if we don't already have some. The
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* application must reap them itself, as they reside on the shared cq ring.
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@ -7910,6 +8114,9 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
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struct io_rings *rings = ctx->rings;
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ktime_t timeout = KTIME_MAX;
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int ret;
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#ifdef CONFIG_NET_RX_BUSY_POLL
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LIST_HEAD(local_napi_list);
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#endif
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do {
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io_cqring_overflow_flush(ctx);
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@ -7932,13 +8139,29 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
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return ret;
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}
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#ifdef CONFIG_NET_RX_BUSY_POLL
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iowq.busy_poll_to = 0;
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if (!(ctx->flags & IORING_SETUP_SQPOLL)) {
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spin_lock(&ctx->napi_lock);
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list_splice_init(&ctx->napi_list, &local_napi_list);
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spin_unlock(&ctx->napi_lock);
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}
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#endif
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if (uts) {
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struct timespec64 ts;
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if (get_timespec64(&ts, uts))
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return -EFAULT;
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#ifdef CONFIG_NET_RX_BUSY_POLL
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if (!list_empty(&local_napi_list))
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io_adjust_busy_loop_timeout(&ts, &iowq);
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#endif
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timeout = ktime_add_ns(timespec64_to_ktime(ts), ktime_get_ns());
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}
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#ifdef CONFIG_NET_RX_BUSY_POLL
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else if (!list_empty(&local_napi_list))
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iowq.busy_poll_to = READ_ONCE(sysctl_net_busy_poll);
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#endif
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init_waitqueue_func_entry(&iowq.wq, io_wake_function);
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iowq.wq.private = current;
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@ -7948,6 +8171,12 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
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iowq.cq_tail = READ_ONCE(ctx->rings->cq.head) + min_events;
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trace_io_uring_cqring_wait(ctx, min_events);
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#ifdef CONFIG_NET_RX_BUSY_POLL
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if (iowq.busy_poll_to)
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io_blocking_napi_busy_loop(&local_napi_list, &iowq);
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if (!list_empty(&local_napi_list))
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io_putback_napi_list(ctx, &local_napi_list);
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#endif
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do {
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/* if we can't even flush overflow, don't wait for more */
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if (!io_cqring_overflow_flush(ctx)) {
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@ -9709,6 +9938,7 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
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io_req_caches_free(ctx);
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if (ctx->hash_map)
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io_wq_put_hash(ctx->hash_map);
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io_free_napi_list(ctx);
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kfree(ctx->cancel_hash);
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kfree(ctx->dummy_ubuf);
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kfree(ctx);
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