From 200f3abd14db55f9aadcb74f4e7a678f1c469ba1 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Mon, 3 Jun 2024 11:51:19 -0600 Subject: [PATCH] io_uring/eventfd: move eventfd handling to separate file This is pretty nicely abstracted already, but let's move it to a separate file rather than have it in the main io_uring file. With that, we can also move the io_ev_fd struct and enum out of global scope. Signed-off-by: Jens Axboe --- include/linux/io_uring_types.h | 8 -- io_uring/Makefile | 6 +- io_uring/eventfd.c | 160 +++++++++++++++++++++++++++++++++ io_uring/eventfd.h | 8 ++ io_uring/io_uring.c | 82 +---------------- io_uring/io_uring.h | 6 -- io_uring/register.c | 56 +----------- 7 files changed, 173 insertions(+), 153 deletions(-) create mode 100644 io_uring/eventfd.c create mode 100644 io_uring/eventfd.h diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h index 93c9044ec3fe..850e30be9322 100644 --- a/include/linux/io_uring_types.h +++ b/include/linux/io_uring_types.h @@ -211,14 +211,6 @@ struct io_submit_state { struct blk_plug plug; }; -struct io_ev_fd { - struct eventfd_ctx *cq_ev_fd; - unsigned int eventfd_async: 1; - struct rcu_head rcu; - atomic_t refs; - atomic_t ops; -}; - struct io_alloc_cache { void **entries; unsigned int nr_cached; diff --git a/io_uring/Makefile b/io_uring/Makefile index fc1b23c524e8..61923e11c767 100644 --- a/io_uring/Makefile +++ b/io_uring/Makefile @@ -4,9 +4,9 @@ obj-$(CONFIG_IO_URING) += io_uring.o opdef.o kbuf.o rsrc.o notif.o \ tctx.o filetable.o rw.o net.o poll.o \ - uring_cmd.o openclose.o sqpoll.o \ - xattr.o nop.o fs.o splice.o sync.o \ - msg_ring.o advise.o openclose.o \ + eventfd.o uring_cmd.o openclose.o \ + sqpoll.o xattr.o nop.o fs.o splice.o \ + sync.o msg_ring.o advise.o openclose.o \ epoll.o statx.o timeout.o fdinfo.o \ cancel.o waitid.o register.o \ truncate.o memmap.o diff --git a/io_uring/eventfd.c b/io_uring/eventfd.c new file mode 100644 index 000000000000..b9384503a2b7 --- /dev/null +++ b/io_uring/eventfd.c @@ -0,0 +1,160 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include + +#include "io-wq.h" +#include "eventfd.h" + +struct io_ev_fd { + struct eventfd_ctx *cq_ev_fd; + unsigned int eventfd_async: 1; + struct rcu_head rcu; + atomic_t refs; + atomic_t ops; +}; + +enum { + IO_EVENTFD_OP_SIGNAL_BIT, +}; + +static void io_eventfd_free(struct rcu_head *rcu) +{ + struct io_ev_fd *ev_fd = container_of(rcu, struct io_ev_fd, rcu); + + eventfd_ctx_put(ev_fd->cq_ev_fd); + kfree(ev_fd); +} + +static void io_eventfd_do_signal(struct rcu_head *rcu) +{ + struct io_ev_fd *ev_fd = container_of(rcu, struct io_ev_fd, rcu); + + eventfd_signal_mask(ev_fd->cq_ev_fd, EPOLL_URING_WAKE); + + if (atomic_dec_and_test(&ev_fd->refs)) + io_eventfd_free(rcu); +} + +void io_eventfd_signal(struct io_ring_ctx *ctx) +{ + struct io_ev_fd *ev_fd = NULL; + + if (READ_ONCE(ctx->rings->cq_flags) & IORING_CQ_EVENTFD_DISABLED) + return; + + guard(rcu)(); + + /* + * rcu_dereference ctx->io_ev_fd once and use it for both for checking + * and eventfd_signal + */ + ev_fd = rcu_dereference(ctx->io_ev_fd); + + /* + * Check again if ev_fd exists incase an io_eventfd_unregister call + * completed between the NULL check of ctx->io_ev_fd at the start of + * the function and rcu_read_lock. + */ + if (unlikely(!ev_fd)) + return; + if (!atomic_inc_not_zero(&ev_fd->refs)) + return; + if (ev_fd->eventfd_async && !io_wq_current_is_worker()) + goto out; + + if (likely(eventfd_signal_allowed())) { + eventfd_signal_mask(ev_fd->cq_ev_fd, EPOLL_URING_WAKE); + } else { + if (!atomic_fetch_or(BIT(IO_EVENTFD_OP_SIGNAL_BIT), &ev_fd->ops)) { + call_rcu_hurry(&ev_fd->rcu, io_eventfd_do_signal); + return; + } + } +out: + if (atomic_dec_and_test(&ev_fd->refs)) + call_rcu(&ev_fd->rcu, io_eventfd_free); +} + +void io_eventfd_flush_signal(struct io_ring_ctx *ctx) +{ + bool skip; + + spin_lock(&ctx->completion_lock); + + /* + * Eventfd should only get triggered when at least one event has been + * posted. Some applications rely on the eventfd notification count + * only changing IFF a new CQE has been added to the CQ ring. There's + * no depedency on 1:1 relationship between how many times this + * function is called (and hence the eventfd count) and number of CQEs + * posted to the CQ ring. + */ + skip = ctx->cached_cq_tail == ctx->evfd_last_cq_tail; + ctx->evfd_last_cq_tail = ctx->cached_cq_tail; + spin_unlock(&ctx->completion_lock); + if (skip) + return; + + io_eventfd_signal(ctx); +} + +int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg, + unsigned int eventfd_async) +{ + struct io_ev_fd *ev_fd; + __s32 __user *fds = arg; + int fd; + + ev_fd = rcu_dereference_protected(ctx->io_ev_fd, + lockdep_is_held(&ctx->uring_lock)); + if (ev_fd) + return -EBUSY; + + if (copy_from_user(&fd, fds, sizeof(*fds))) + return -EFAULT; + + ev_fd = kmalloc(sizeof(*ev_fd), GFP_KERNEL); + if (!ev_fd) + return -ENOMEM; + + ev_fd->cq_ev_fd = eventfd_ctx_fdget(fd); + if (IS_ERR(ev_fd->cq_ev_fd)) { + int ret = PTR_ERR(ev_fd->cq_ev_fd); + kfree(ev_fd); + return ret; + } + + spin_lock(&ctx->completion_lock); + ctx->evfd_last_cq_tail = ctx->cached_cq_tail; + spin_unlock(&ctx->completion_lock); + + ev_fd->eventfd_async = eventfd_async; + ctx->has_evfd = true; + atomic_set(&ev_fd->refs, 1); + atomic_set(&ev_fd->ops, 0); + rcu_assign_pointer(ctx->io_ev_fd, ev_fd); + return 0; +} + +int io_eventfd_unregister(struct io_ring_ctx *ctx) +{ + struct io_ev_fd *ev_fd; + + ev_fd = rcu_dereference_protected(ctx->io_ev_fd, + lockdep_is_held(&ctx->uring_lock)); + if (ev_fd) { + ctx->has_evfd = false; + rcu_assign_pointer(ctx->io_ev_fd, NULL); + if (atomic_dec_and_test(&ev_fd->refs)) + call_rcu(&ev_fd->rcu, io_eventfd_free); + return 0; + } + + return -ENXIO; +} diff --git a/io_uring/eventfd.h b/io_uring/eventfd.h new file mode 100644 index 000000000000..d394f49c6321 --- /dev/null +++ b/io_uring/eventfd.h @@ -0,0 +1,8 @@ + +struct io_ring_ctx; +int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg, + unsigned int eventfd_async); +int io_eventfd_unregister(struct io_ring_ctx *ctx); + +void io_eventfd_flush_signal(struct io_ring_ctx *ctx); +void io_eventfd_signal(struct io_ring_ctx *ctx); diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 0a24feec27f7..d10678b9d519 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -101,6 +101,7 @@ #include "poll.h" #include "rw.h" #include "alloc_cache.h" +#include "eventfd.h" #define IORING_MAX_ENTRIES 32768 #define IORING_MAX_CQ_ENTRIES (2 * IORING_MAX_ENTRIES) @@ -541,87 +542,6 @@ static __cold void io_queue_deferred(struct io_ring_ctx *ctx) } } -void io_eventfd_free(struct rcu_head *rcu) -{ - struct io_ev_fd *ev_fd = container_of(rcu, struct io_ev_fd, rcu); - - eventfd_ctx_put(ev_fd->cq_ev_fd); - kfree(ev_fd); -} - -void io_eventfd_do_signal(struct rcu_head *rcu) -{ - struct io_ev_fd *ev_fd = container_of(rcu, struct io_ev_fd, rcu); - - eventfd_signal_mask(ev_fd->cq_ev_fd, EPOLL_URING_WAKE); - - if (atomic_dec_and_test(&ev_fd->refs)) - io_eventfd_free(rcu); -} - -static void io_eventfd_signal(struct io_ring_ctx *ctx) -{ - struct io_ev_fd *ev_fd = NULL; - - if (READ_ONCE(ctx->rings->cq_flags) & IORING_CQ_EVENTFD_DISABLED) - return; - - guard(rcu)(); - - /* - * rcu_dereference ctx->io_ev_fd once and use it for both for checking - * and eventfd_signal - */ - ev_fd = rcu_dereference(ctx->io_ev_fd); - - /* - * Check again if ev_fd exists incase an io_eventfd_unregister call - * completed between the NULL check of ctx->io_ev_fd at the start of - * the function and rcu_read_lock. - */ - if (unlikely(!ev_fd)) - return; - if (!atomic_inc_not_zero(&ev_fd->refs)) - return; - if (ev_fd->eventfd_async && !io_wq_current_is_worker()) - goto out; - - if (likely(eventfd_signal_allowed())) { - eventfd_signal_mask(ev_fd->cq_ev_fd, EPOLL_URING_WAKE); - } else { - if (!atomic_fetch_or(BIT(IO_EVENTFD_OP_SIGNAL_BIT), &ev_fd->ops)) { - call_rcu_hurry(&ev_fd->rcu, io_eventfd_do_signal); - return; - } - } -out: - if (atomic_dec_and_test(&ev_fd->refs)) - call_rcu(&ev_fd->rcu, io_eventfd_free); -} - -static void io_eventfd_flush_signal(struct io_ring_ctx *ctx) -{ - bool skip; - - spin_lock(&ctx->completion_lock); - - /* - * Eventfd should only get triggered when at least one event has been - * posted. Some applications rely on the eventfd notification count - * only changing IFF a new CQE has been added to the CQ ring. There's - * no depedency on 1:1 relationship between how many times this - * function is called (and hence the eventfd count) and number of CQEs - * posted to the CQ ring. - */ - skip = ctx->cached_cq_tail == ctx->evfd_last_cq_tail; - ctx->evfd_last_cq_tail = ctx->cached_cq_tail; - spin_unlock(&ctx->completion_lock); - if (skip) - return; - - io_eventfd_signal(ctx); -} - void __io_commit_cqring_flush(struct io_ring_ctx *ctx) { if (ctx->poll_activated) diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h index 2b08b402b716..cd43924eed04 100644 --- a/io_uring/io_uring.h +++ b/io_uring/io_uring.h @@ -104,12 +104,6 @@ bool __io_alloc_req_refill(struct io_ring_ctx *ctx); bool io_match_task_safe(struct io_kiocb *head, struct task_struct *task, bool cancel_all); -enum { - IO_EVENTFD_OP_SIGNAL_BIT, -}; - -void io_eventfd_do_signal(struct rcu_head *rcu); -void io_eventfd_free(struct rcu_head *rcu); void io_activate_pollwq(struct io_ring_ctx *ctx); static inline void io_lockdep_assert_cq_locked(struct io_ring_ctx *ctx) diff --git a/io_uring/register.c b/io_uring/register.c index 212711e9bc8a..f121e02f5e10 100644 --- a/io_uring/register.c +++ b/io_uring/register.c @@ -27,65 +27,11 @@ #include "cancel.h" #include "kbuf.h" #include "napi.h" +#include "eventfd.h" #define IORING_MAX_RESTRICTIONS (IORING_RESTRICTION_LAST + \ IORING_REGISTER_LAST + IORING_OP_LAST) -static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg, - unsigned int eventfd_async) -{ - struct io_ev_fd *ev_fd; - __s32 __user *fds = arg; - int fd; - - ev_fd = rcu_dereference_protected(ctx->io_ev_fd, - lockdep_is_held(&ctx->uring_lock)); - if (ev_fd) - return -EBUSY; - - if (copy_from_user(&fd, fds, sizeof(*fds))) - return -EFAULT; - - ev_fd = kmalloc(sizeof(*ev_fd), GFP_KERNEL); - if (!ev_fd) - return -ENOMEM; - - ev_fd->cq_ev_fd = eventfd_ctx_fdget(fd); - if (IS_ERR(ev_fd->cq_ev_fd)) { - int ret = PTR_ERR(ev_fd->cq_ev_fd); - kfree(ev_fd); - return ret; - } - - spin_lock(&ctx->completion_lock); - ctx->evfd_last_cq_tail = ctx->cached_cq_tail; - spin_unlock(&ctx->completion_lock); - - ev_fd->eventfd_async = eventfd_async; - ctx->has_evfd = true; - atomic_set(&ev_fd->refs, 1); - atomic_set(&ev_fd->ops, 0); - rcu_assign_pointer(ctx->io_ev_fd, ev_fd); - return 0; -} - -int io_eventfd_unregister(struct io_ring_ctx *ctx) -{ - struct io_ev_fd *ev_fd; - - ev_fd = rcu_dereference_protected(ctx->io_ev_fd, - lockdep_is_held(&ctx->uring_lock)); - if (ev_fd) { - ctx->has_evfd = false; - rcu_assign_pointer(ctx->io_ev_fd, NULL); - if (atomic_dec_and_test(&ev_fd->refs)) - call_rcu(&ev_fd->rcu, io_eventfd_free); - return 0; - } - - return -ENXIO; -} - static __cold int io_probe(struct io_ring_ctx *ctx, void __user *arg, unsigned nr_args) {