linux-stable/io_uring/io_uring.h
Jens Axboe 704ea888d6 io_uring/poll: add requeue return code from poll multishot handling
Since our poll handling is edge triggered, multishot handlers retry
internally until they know that no more data is available. In
preparation for limiting these retries, add an internal return code,
IOU_REQUEUE, which can be used to inform the poll backend about the
handler wanting to retry, but that this should happen through a normal
task_work requeue rather than keep hammering on the issue side for this
one request.

No functional changes in this patch, nobody is using this return code
just yet.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-01-29 13:19:47 -07:00

401 lines
11 KiB
C

#ifndef IOU_CORE_H
#define IOU_CORE_H
#include <linux/errno.h>
#include <linux/lockdep.h>
#include <linux/resume_user_mode.h>
#include <linux/kasan.h>
#include <linux/io_uring_types.h>
#include <uapi/linux/eventpoll.h>
#include "io-wq.h"
#include "slist.h"
#include "filetable.h"
#ifndef CREATE_TRACE_POINTS
#include <trace/events/io_uring.h>
#endif
enum {
IOU_OK = 0,
IOU_ISSUE_SKIP_COMPLETE = -EIOCBQUEUED,
/*
* Requeue the task_work to restart operations on this request. The
* actual value isn't important, should just be not an otherwise
* valid error code, yet less than -MAX_ERRNO and valid internally.
*/
IOU_REQUEUE = -3072,
/*
* Intended only when both IO_URING_F_MULTISHOT is passed
* to indicate to the poll runner that multishot should be
* removed and the result is set on req->cqe.res.
*/
IOU_STOP_MULTISHOT = -ECANCELED,
};
bool io_cqe_cache_refill(struct io_ring_ctx *ctx, bool overflow);
void io_req_cqe_overflow(struct io_kiocb *req);
int io_run_task_work_sig(struct io_ring_ctx *ctx);
void io_req_defer_failed(struct io_kiocb *req, s32 res);
void io_req_complete_post(struct io_kiocb *req, unsigned issue_flags);
bool io_post_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags);
bool io_fill_cqe_req_aux(struct io_kiocb *req, bool defer, s32 res, u32 cflags);
void __io_commit_cqring_flush(struct io_ring_ctx *ctx);
struct page **io_pin_pages(unsigned long ubuf, unsigned long len, int *npages);
struct file *io_file_get_normal(struct io_kiocb *req, int fd);
struct file *io_file_get_fixed(struct io_kiocb *req, int fd,
unsigned issue_flags);
void __io_req_task_work_add(struct io_kiocb *req, unsigned flags);
bool io_alloc_async_data(struct io_kiocb *req);
void io_req_task_queue(struct io_kiocb *req);
void io_queue_iowq(struct io_kiocb *req, struct io_tw_state *ts_dont_use);
void io_req_task_complete(struct io_kiocb *req, struct io_tw_state *ts);
void io_req_task_queue_fail(struct io_kiocb *req, int ret);
void io_req_task_submit(struct io_kiocb *req, struct io_tw_state *ts);
void tctx_task_work(struct callback_head *cb);
__cold void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd);
int io_uring_alloc_task_context(struct task_struct *task,
struct io_ring_ctx *ctx);
int io_ring_add_registered_file(struct io_uring_task *tctx, struct file *file,
int start, int end);
int io_poll_issue(struct io_kiocb *req, struct io_tw_state *ts);
int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr);
int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin);
void __io_submit_flush_completions(struct io_ring_ctx *ctx);
int io_req_prep_async(struct io_kiocb *req);
struct io_wq_work *io_wq_free_work(struct io_wq_work *work);
void io_wq_submit_work(struct io_wq_work *work);
void io_free_req(struct io_kiocb *req);
void io_queue_next(struct io_kiocb *req);
void io_task_refs_refill(struct io_uring_task *tctx);
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);
void *io_mem_alloc(size_t size);
void io_mem_free(void *ptr);
enum {
IO_EVENTFD_OP_SIGNAL_BIT,
IO_EVENTFD_OP_FREE_BIT,
};
void io_eventfd_ops(struct rcu_head *rcu);
void io_activate_pollwq(struct io_ring_ctx *ctx);
#if defined(CONFIG_PROVE_LOCKING)
static inline void io_lockdep_assert_cq_locked(struct io_ring_ctx *ctx)
{
lockdep_assert(in_task());
if (ctx->flags & IORING_SETUP_IOPOLL) {
lockdep_assert_held(&ctx->uring_lock);
} else if (!ctx->task_complete) {
lockdep_assert_held(&ctx->completion_lock);
} else if (ctx->submitter_task) {
/*
* ->submitter_task may be NULL and we can still post a CQE,
* if the ring has been setup with IORING_SETUP_R_DISABLED.
* Not from an SQE, as those cannot be submitted, but via
* updating tagged resources.
*/
if (ctx->submitter_task->flags & PF_EXITING)
lockdep_assert(current_work());
else
lockdep_assert(current == ctx->submitter_task);
}
}
#else
static inline void io_lockdep_assert_cq_locked(struct io_ring_ctx *ctx)
{
}
#endif
static inline void io_req_task_work_add(struct io_kiocb *req)
{
__io_req_task_work_add(req, 0);
}
#define io_for_each_link(pos, head) \
for (pos = (head); pos; pos = pos->link)
static inline bool io_get_cqe_overflow(struct io_ring_ctx *ctx,
struct io_uring_cqe **ret,
bool overflow)
{
io_lockdep_assert_cq_locked(ctx);
if (unlikely(ctx->cqe_cached >= ctx->cqe_sentinel)) {
if (unlikely(!io_cqe_cache_refill(ctx, overflow)))
return false;
}
*ret = ctx->cqe_cached;
ctx->cached_cq_tail++;
ctx->cqe_cached++;
if (ctx->flags & IORING_SETUP_CQE32)
ctx->cqe_cached++;
return true;
}
static inline bool io_get_cqe(struct io_ring_ctx *ctx, struct io_uring_cqe **ret)
{
return io_get_cqe_overflow(ctx, ret, false);
}
static __always_inline bool io_fill_cqe_req(struct io_ring_ctx *ctx,
struct io_kiocb *req)
{
struct io_uring_cqe *cqe;
/*
* If we can't get a cq entry, userspace overflowed the
* submission (by quite a lot). Increment the overflow count in
* the ring.
*/
if (unlikely(!io_get_cqe(ctx, &cqe)))
return false;
if (trace_io_uring_complete_enabled())
trace_io_uring_complete(req->ctx, req, req->cqe.user_data,
req->cqe.res, req->cqe.flags,
req->big_cqe.extra1, req->big_cqe.extra2);
memcpy(cqe, &req->cqe, sizeof(*cqe));
if (ctx->flags & IORING_SETUP_CQE32) {
memcpy(cqe->big_cqe, &req->big_cqe, sizeof(*cqe));
memset(&req->big_cqe, 0, sizeof(req->big_cqe));
}
return true;
}
static inline void req_set_fail(struct io_kiocb *req)
{
req->flags |= REQ_F_FAIL;
if (req->flags & REQ_F_CQE_SKIP) {
req->flags &= ~REQ_F_CQE_SKIP;
req->flags |= REQ_F_SKIP_LINK_CQES;
}
}
static inline void io_req_set_res(struct io_kiocb *req, s32 res, u32 cflags)
{
req->cqe.res = res;
req->cqe.flags = cflags;
}
static inline bool req_has_async_data(struct io_kiocb *req)
{
return req->flags & REQ_F_ASYNC_DATA;
}
static inline void io_put_file(struct io_kiocb *req)
{
if (!(req->flags & REQ_F_FIXED_FILE) && req->file)
fput(req->file);
}
static inline void io_ring_submit_unlock(struct io_ring_ctx *ctx,
unsigned issue_flags)
{
lockdep_assert_held(&ctx->uring_lock);
if (issue_flags & IO_URING_F_UNLOCKED)
mutex_unlock(&ctx->uring_lock);
}
static inline void io_ring_submit_lock(struct io_ring_ctx *ctx,
unsigned issue_flags)
{
/*
* "Normal" inline submissions always hold the uring_lock, since we
* grab it from the system call. Same is true for the SQPOLL offload.
* The only exception is when we've detached the request and issue it
* from an async worker thread, grab the lock for that case.
*/
if (issue_flags & IO_URING_F_UNLOCKED)
mutex_lock(&ctx->uring_lock);
lockdep_assert_held(&ctx->uring_lock);
}
static inline void io_commit_cqring(struct io_ring_ctx *ctx)
{
/* order cqe stores with ring update */
smp_store_release(&ctx->rings->cq.tail, ctx->cached_cq_tail);
}
static inline void io_poll_wq_wake(struct io_ring_ctx *ctx)
{
if (wq_has_sleeper(&ctx->poll_wq))
__wake_up(&ctx->poll_wq, TASK_NORMAL, 0,
poll_to_key(EPOLL_URING_WAKE | EPOLLIN));
}
static inline void io_cqring_wake(struct io_ring_ctx *ctx)
{
/*
* Trigger waitqueue handler on all waiters on our waitqueue. This
* won't necessarily wake up all the tasks, io_should_wake() will make
* that decision.
*
* Pass in EPOLLIN|EPOLL_URING_WAKE as the poll wakeup key. The latter
* set in the mask so that if we recurse back into our own poll
* waitqueue handlers, we know we have a dependency between eventfd or
* epoll and should terminate multishot poll at that point.
*/
if (wq_has_sleeper(&ctx->cq_wait))
__wake_up(&ctx->cq_wait, TASK_NORMAL, 0,
poll_to_key(EPOLL_URING_WAKE | EPOLLIN));
}
static inline bool io_sqring_full(struct io_ring_ctx *ctx)
{
struct io_rings *r = ctx->rings;
return READ_ONCE(r->sq.tail) - ctx->cached_sq_head == ctx->sq_entries;
}
static inline unsigned int io_sqring_entries(struct io_ring_ctx *ctx)
{
struct io_rings *rings = ctx->rings;
unsigned int entries;
/* make sure SQ entry isn't read before tail */
entries = smp_load_acquire(&rings->sq.tail) - ctx->cached_sq_head;
return min(entries, ctx->sq_entries);
}
static inline int io_run_task_work(void)
{
/*
* Always check-and-clear the task_work notification signal. With how
* signaling works for task_work, we can find it set with nothing to
* run. We need to clear it for that case, like get_signal() does.
*/
if (test_thread_flag(TIF_NOTIFY_SIGNAL))
clear_notify_signal();
/*
* PF_IO_WORKER never returns to userspace, so check here if we have
* notify work that needs processing.
*/
if (current->flags & PF_IO_WORKER &&
test_thread_flag(TIF_NOTIFY_RESUME)) {
__set_current_state(TASK_RUNNING);
resume_user_mode_work(NULL);
}
if (task_work_pending(current)) {
__set_current_state(TASK_RUNNING);
task_work_run();
return 1;
}
return 0;
}
static inline bool io_task_work_pending(struct io_ring_ctx *ctx)
{
return task_work_pending(current) || !wq_list_empty(&ctx->work_llist);
}
static inline void io_tw_lock(struct io_ring_ctx *ctx, struct io_tw_state *ts)
{
if (!ts->locked) {
mutex_lock(&ctx->uring_lock);
ts->locked = true;
}
}
/*
* Don't complete immediately but use deferred completion infrastructure.
* Protected by ->uring_lock and can only be used either with
* IO_URING_F_COMPLETE_DEFER or inside a tw handler holding the mutex.
*/
static inline void io_req_complete_defer(struct io_kiocb *req)
__must_hold(&req->ctx->uring_lock)
{
struct io_submit_state *state = &req->ctx->submit_state;
lockdep_assert_held(&req->ctx->uring_lock);
wq_list_add_tail(&req->comp_list, &state->compl_reqs);
}
static inline void io_commit_cqring_flush(struct io_ring_ctx *ctx)
{
if (unlikely(ctx->off_timeout_used || ctx->drain_active ||
ctx->has_evfd || ctx->poll_activated))
__io_commit_cqring_flush(ctx);
}
static inline void io_get_task_refs(int nr)
{
struct io_uring_task *tctx = current->io_uring;
tctx->cached_refs -= nr;
if (unlikely(tctx->cached_refs < 0))
io_task_refs_refill(tctx);
}
static inline bool io_req_cache_empty(struct io_ring_ctx *ctx)
{
return !ctx->submit_state.free_list.next;
}
extern struct kmem_cache *req_cachep;
extern struct kmem_cache *io_buf_cachep;
static inline struct io_kiocb *io_extract_req(struct io_ring_ctx *ctx)
{
struct io_kiocb *req;
req = container_of(ctx->submit_state.free_list.next, struct io_kiocb, comp_list);
wq_stack_extract(&ctx->submit_state.free_list);
return req;
}
static inline bool io_alloc_req(struct io_ring_ctx *ctx, struct io_kiocb **req)
{
if (unlikely(io_req_cache_empty(ctx))) {
if (!__io_alloc_req_refill(ctx))
return false;
}
*req = io_extract_req(ctx);
return true;
}
static inline bool io_allowed_defer_tw_run(struct io_ring_ctx *ctx)
{
return likely(ctx->submitter_task == current);
}
static inline bool io_allowed_run_tw(struct io_ring_ctx *ctx)
{
return likely(!(ctx->flags & IORING_SETUP_DEFER_TASKRUN) ||
ctx->submitter_task == current);
}
static inline void io_req_queue_tw_complete(struct io_kiocb *req, s32 res)
{
io_req_set_res(req, res, 0);
req->io_task_work.func = io_req_task_complete;
io_req_task_work_add(req);
}
/*
* IORING_SETUP_SQE128 contexts allocate twice the normal SQE size for each
* slot.
*/
static inline size_t uring_sqe_size(struct io_ring_ctx *ctx)
{
if (ctx->flags & IORING_SETUP_SQE128)
return 2 * sizeof(struct io_uring_sqe);
return sizeof(struct io_uring_sqe);
}
#endif