linuxdebug/io_uring/timeout.c

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2024-07-16 15:50:57 +02:00
// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/io_uring.h>
#include <trace/events/io_uring.h>
#include <uapi/linux/io_uring.h>
#include "io_uring.h"
#include "refs.h"
#include "cancel.h"
#include "timeout.h"
struct io_timeout {
struct file *file;
u32 off;
u32 target_seq;
struct list_head list;
/* head of the link, used by linked timeouts only */
struct io_kiocb *head;
/* for linked completions */
struct io_kiocb *prev;
};
struct io_timeout_rem {
struct file *file;
u64 addr;
/* timeout update */
struct timespec64 ts;
u32 flags;
bool ltimeout;
};
static inline bool io_is_timeout_noseq(struct io_kiocb *req)
{
struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
return !timeout->off;
}
static inline void io_put_req(struct io_kiocb *req)
{
if (req_ref_put_and_test(req)) {
io_queue_next(req);
io_free_req(req);
}
}
static bool io_kill_timeout(struct io_kiocb *req, int status)
__must_hold(&req->ctx->completion_lock)
__must_hold(&req->ctx->timeout_lock)
{
struct io_timeout_data *io = req->async_data;
if (hrtimer_try_to_cancel(&io->timer) != -1) {
struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
if (status)
req_set_fail(req);
atomic_set(&req->ctx->cq_timeouts,
atomic_read(&req->ctx->cq_timeouts) + 1);
list_del_init(&timeout->list);
io_req_queue_tw_complete(req, status);
return true;
}
return false;
}
__cold void io_flush_timeouts(struct io_ring_ctx *ctx)
__must_hold(&ctx->completion_lock)
{
u32 seq;
struct io_timeout *timeout, *tmp;
spin_lock_irq(&ctx->timeout_lock);
seq = ctx->cached_cq_tail - atomic_read(&ctx->cq_timeouts);
list_for_each_entry_safe(timeout, tmp, &ctx->timeout_list, list) {
struct io_kiocb *req = cmd_to_io_kiocb(timeout);
u32 events_needed, events_got;
if (io_is_timeout_noseq(req))
break;
/*
* Since seq can easily wrap around over time, subtract
* the last seq at which timeouts were flushed before comparing.
* Assuming not more than 2^31-1 events have happened since,
* these subtractions won't have wrapped, so we can check if
* target is in [last_seq, current_seq] by comparing the two.
*/
events_needed = timeout->target_seq - ctx->cq_last_tm_flush;
events_got = seq - ctx->cq_last_tm_flush;
if (events_got < events_needed)
break;
io_kill_timeout(req, 0);
}
ctx->cq_last_tm_flush = seq;
spin_unlock_irq(&ctx->timeout_lock);
}
static void io_req_tw_fail_links(struct io_kiocb *link, bool *locked)
{
io_tw_lock(link->ctx, locked);
while (link) {
struct io_kiocb *nxt = link->link;
long res = -ECANCELED;
if (link->flags & REQ_F_FAIL)
res = link->cqe.res;
link->link = NULL;
io_req_set_res(link, res, 0);
io_req_task_complete(link, locked);
link = nxt;
}
}
static void io_fail_links(struct io_kiocb *req)
__must_hold(&req->ctx->completion_lock)
{
struct io_kiocb *link = req->link;
bool ignore_cqes = req->flags & REQ_F_SKIP_LINK_CQES;
if (!link)
return;
while (link) {
if (ignore_cqes)
link->flags |= REQ_F_CQE_SKIP;
else
link->flags &= ~REQ_F_CQE_SKIP;
trace_io_uring_fail_link(req, link);
link = link->link;
}
link = req->link;
link->io_task_work.func = io_req_tw_fail_links;
io_req_task_work_add(link);
req->link = NULL;
}
static inline void io_remove_next_linked(struct io_kiocb *req)
{
struct io_kiocb *nxt = req->link;
req->link = nxt->link;
nxt->link = NULL;
}
void io_disarm_next(struct io_kiocb *req)
__must_hold(&req->ctx->completion_lock)
{
struct io_kiocb *link = NULL;
if (req->flags & REQ_F_ARM_LTIMEOUT) {
link = req->link;
req->flags &= ~REQ_F_ARM_LTIMEOUT;
if (link && link->opcode == IORING_OP_LINK_TIMEOUT) {
io_remove_next_linked(req);
io_req_queue_tw_complete(link, -ECANCELED);
}
} else if (req->flags & REQ_F_LINK_TIMEOUT) {
struct io_ring_ctx *ctx = req->ctx;
spin_lock_irq(&ctx->timeout_lock);
link = io_disarm_linked_timeout(req);
spin_unlock_irq(&ctx->timeout_lock);
if (link)
io_req_queue_tw_complete(link, -ECANCELED);
}
if (unlikely((req->flags & REQ_F_FAIL) &&
!(req->flags & REQ_F_HARDLINK)))
io_fail_links(req);
}
struct io_kiocb *__io_disarm_linked_timeout(struct io_kiocb *req,
struct io_kiocb *link)
__must_hold(&req->ctx->completion_lock)
__must_hold(&req->ctx->timeout_lock)
{
struct io_timeout_data *io = link->async_data;
struct io_timeout *timeout = io_kiocb_to_cmd(link, struct io_timeout);
io_remove_next_linked(req);
timeout->head = NULL;
if (hrtimer_try_to_cancel(&io->timer) != -1) {
list_del(&timeout->list);
return link;
}
return NULL;
}
static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer)
{
struct io_timeout_data *data = container_of(timer,
struct io_timeout_data, timer);
struct io_kiocb *req = data->req;
struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
struct io_ring_ctx *ctx = req->ctx;
unsigned long flags;
spin_lock_irqsave(&ctx->timeout_lock, flags);
list_del_init(&timeout->list);
atomic_set(&req->ctx->cq_timeouts,
atomic_read(&req->ctx->cq_timeouts) + 1);
spin_unlock_irqrestore(&ctx->timeout_lock, flags);
if (!(data->flags & IORING_TIMEOUT_ETIME_SUCCESS))
req_set_fail(req);
io_req_set_res(req, -ETIME, 0);
req->io_task_work.func = io_req_task_complete;
io_req_task_work_add(req);
return HRTIMER_NORESTART;
}
static struct io_kiocb *io_timeout_extract(struct io_ring_ctx *ctx,
struct io_cancel_data *cd)
__must_hold(&ctx->timeout_lock)
{
struct io_timeout *timeout;
struct io_timeout_data *io;
struct io_kiocb *req = NULL;
list_for_each_entry(timeout, &ctx->timeout_list, list) {
struct io_kiocb *tmp = cmd_to_io_kiocb(timeout);
if (!(cd->flags & IORING_ASYNC_CANCEL_ANY) &&
cd->data != tmp->cqe.user_data)
continue;
if (cd->flags & (IORING_ASYNC_CANCEL_ALL|IORING_ASYNC_CANCEL_ANY)) {
if (cd->seq == tmp->work.cancel_seq)
continue;
tmp->work.cancel_seq = cd->seq;
}
req = tmp;
break;
}
if (!req)
return ERR_PTR(-ENOENT);
io = req->async_data;
if (hrtimer_try_to_cancel(&io->timer) == -1)
return ERR_PTR(-EALREADY);
timeout = io_kiocb_to_cmd(req, struct io_timeout);
list_del_init(&timeout->list);
return req;
}
int io_timeout_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd)
__must_hold(&ctx->completion_lock)
{
struct io_kiocb *req;
spin_lock_irq(&ctx->timeout_lock);
req = io_timeout_extract(ctx, cd);
spin_unlock_irq(&ctx->timeout_lock);
if (IS_ERR(req))
return PTR_ERR(req);
io_req_task_queue_fail(req, -ECANCELED);
return 0;
}
static void io_req_task_link_timeout(struct io_kiocb *req, bool *locked)
{
unsigned issue_flags = *locked ? 0 : IO_URING_F_UNLOCKED;
struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
struct io_kiocb *prev = timeout->prev;
int ret = -ENOENT;
if (prev) {
if (!(req->task->flags & PF_EXITING)) {
struct io_cancel_data cd = {
.ctx = req->ctx,
.data = prev->cqe.user_data,
};
ret = io_try_cancel(req->task->io_uring, &cd, issue_flags);
}
io_req_set_res(req, ret ?: -ETIME, 0);
io_req_task_complete(req, locked);
io_put_req(prev);
} else {
io_req_set_res(req, -ETIME, 0);
io_req_task_complete(req, locked);
}
}
static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer)
{
struct io_timeout_data *data = container_of(timer,
struct io_timeout_data, timer);
struct io_kiocb *prev, *req = data->req;
struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
struct io_ring_ctx *ctx = req->ctx;
unsigned long flags;
spin_lock_irqsave(&ctx->timeout_lock, flags);
prev = timeout->head;
timeout->head = NULL;
/*
* We don't expect the list to be empty, that will only happen if we
* race with the completion of the linked work.
*/
if (prev) {
io_remove_next_linked(prev);
if (!req_ref_inc_not_zero(prev))
prev = NULL;
}
list_del(&timeout->list);
timeout->prev = prev;
spin_unlock_irqrestore(&ctx->timeout_lock, flags);
req->io_task_work.func = io_req_task_link_timeout;
io_req_task_work_add(req);
return HRTIMER_NORESTART;
}
static clockid_t io_timeout_get_clock(struct io_timeout_data *data)
{
switch (data->flags & IORING_TIMEOUT_CLOCK_MASK) {
case IORING_TIMEOUT_BOOTTIME:
return CLOCK_BOOTTIME;
case IORING_TIMEOUT_REALTIME:
return CLOCK_REALTIME;
default:
/* can't happen, vetted at prep time */
WARN_ON_ONCE(1);
fallthrough;
case 0:
return CLOCK_MONOTONIC;
}
}
static int io_linked_timeout_update(struct io_ring_ctx *ctx, __u64 user_data,
struct timespec64 *ts, enum hrtimer_mode mode)
__must_hold(&ctx->timeout_lock)
{
struct io_timeout_data *io;
struct io_timeout *timeout;
struct io_kiocb *req = NULL;
list_for_each_entry(timeout, &ctx->ltimeout_list, list) {
struct io_kiocb *tmp = cmd_to_io_kiocb(timeout);
if (user_data == tmp->cqe.user_data) {
req = tmp;
break;
}
}
if (!req)
return -ENOENT;
io = req->async_data;
if (hrtimer_try_to_cancel(&io->timer) == -1)
return -EALREADY;
hrtimer_init(&io->timer, io_timeout_get_clock(io), mode);
io->timer.function = io_link_timeout_fn;
hrtimer_start(&io->timer, timespec64_to_ktime(*ts), mode);
return 0;
}
static int io_timeout_update(struct io_ring_ctx *ctx, __u64 user_data,
struct timespec64 *ts, enum hrtimer_mode mode)
__must_hold(&ctx->timeout_lock)
{
struct io_cancel_data cd = { .data = user_data, };
struct io_kiocb *req = io_timeout_extract(ctx, &cd);
struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
struct io_timeout_data *data;
if (IS_ERR(req))
return PTR_ERR(req);
timeout->off = 0; /* noseq */
data = req->async_data;
list_add_tail(&timeout->list, &ctx->timeout_list);
hrtimer_init(&data->timer, io_timeout_get_clock(data), mode);
data->timer.function = io_timeout_fn;
hrtimer_start(&data->timer, timespec64_to_ktime(*ts), mode);
return 0;
}
int io_timeout_remove_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_timeout_rem *tr = io_kiocb_to_cmd(req, struct io_timeout_rem);
if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT)))
return -EINVAL;
if (sqe->buf_index || sqe->len || sqe->splice_fd_in)
return -EINVAL;
tr->ltimeout = false;
tr->addr = READ_ONCE(sqe->addr);
tr->flags = READ_ONCE(sqe->timeout_flags);
if (tr->flags & IORING_TIMEOUT_UPDATE_MASK) {
if (hweight32(tr->flags & IORING_TIMEOUT_CLOCK_MASK) > 1)
return -EINVAL;
if (tr->flags & IORING_LINK_TIMEOUT_UPDATE)
tr->ltimeout = true;
if (tr->flags & ~(IORING_TIMEOUT_UPDATE_MASK|IORING_TIMEOUT_ABS))
return -EINVAL;
if (get_timespec64(&tr->ts, u64_to_user_ptr(sqe->addr2)))
return -EFAULT;
if (tr->ts.tv_sec < 0 || tr->ts.tv_nsec < 0)
return -EINVAL;
} else if (tr->flags) {
/* timeout removal doesn't support flags */
return -EINVAL;
}
return 0;
}
static inline enum hrtimer_mode io_translate_timeout_mode(unsigned int flags)
{
return (flags & IORING_TIMEOUT_ABS) ? HRTIMER_MODE_ABS
: HRTIMER_MODE_REL;
}
/*
* Remove or update an existing timeout command
*/
int io_timeout_remove(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_timeout_rem *tr = io_kiocb_to_cmd(req, struct io_timeout_rem);
struct io_ring_ctx *ctx = req->ctx;
int ret;
if (!(tr->flags & IORING_TIMEOUT_UPDATE)) {
struct io_cancel_data cd = { .data = tr->addr, };
spin_lock(&ctx->completion_lock);
ret = io_timeout_cancel(ctx, &cd);
spin_unlock(&ctx->completion_lock);
} else {
enum hrtimer_mode mode = io_translate_timeout_mode(tr->flags);
spin_lock_irq(&ctx->timeout_lock);
if (tr->ltimeout)
ret = io_linked_timeout_update(ctx, tr->addr, &tr->ts, mode);
else
ret = io_timeout_update(ctx, tr->addr, &tr->ts, mode);
spin_unlock_irq(&ctx->timeout_lock);
}
if (ret < 0)
req_set_fail(req);
io_req_set_res(req, ret, 0);
return IOU_OK;
}
static int __io_timeout_prep(struct io_kiocb *req,
const struct io_uring_sqe *sqe,
bool is_timeout_link)
{
struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
struct io_timeout_data *data;
unsigned flags;
u32 off = READ_ONCE(sqe->off);
if (sqe->buf_index || sqe->len != 1 || sqe->splice_fd_in)
return -EINVAL;
if (off && is_timeout_link)
return -EINVAL;
flags = READ_ONCE(sqe->timeout_flags);
if (flags & ~(IORING_TIMEOUT_ABS | IORING_TIMEOUT_CLOCK_MASK |
IORING_TIMEOUT_ETIME_SUCCESS))
return -EINVAL;
/* more than one clock specified is invalid, obviously */
if (hweight32(flags & IORING_TIMEOUT_CLOCK_MASK) > 1)
return -EINVAL;
INIT_LIST_HEAD(&timeout->list);
timeout->off = off;
if (unlikely(off && !req->ctx->off_timeout_used))
req->ctx->off_timeout_used = true;
if (WARN_ON_ONCE(req_has_async_data(req)))
return -EFAULT;
if (io_alloc_async_data(req))
return -ENOMEM;
data = req->async_data;
data->req = req;
data->flags = flags;
if (get_timespec64(&data->ts, u64_to_user_ptr(sqe->addr)))
return -EFAULT;
if (data->ts.tv_sec < 0 || data->ts.tv_nsec < 0)
return -EINVAL;
INIT_LIST_HEAD(&timeout->list);
data->mode = io_translate_timeout_mode(flags);
hrtimer_init(&data->timer, io_timeout_get_clock(data), data->mode);
if (is_timeout_link) {
struct io_submit_link *link = &req->ctx->submit_state.link;
if (!link->head)
return -EINVAL;
if (link->last->opcode == IORING_OP_LINK_TIMEOUT)
return -EINVAL;
timeout->head = link->last;
link->last->flags |= REQ_F_ARM_LTIMEOUT;
}
return 0;
}
int io_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
return __io_timeout_prep(req, sqe, false);
}
int io_link_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
return __io_timeout_prep(req, sqe, true);
}
int io_timeout(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
struct io_ring_ctx *ctx = req->ctx;
struct io_timeout_data *data = req->async_data;
struct list_head *entry;
u32 tail, off = timeout->off;
spin_lock_irq(&ctx->timeout_lock);
/*
* sqe->off holds how many events that need to occur for this
* timeout event to be satisfied. If it isn't set, then this is
* a pure timeout request, sequence isn't used.
*/
if (io_is_timeout_noseq(req)) {
entry = ctx->timeout_list.prev;
goto add;
}
tail = data_race(ctx->cached_cq_tail) - atomic_read(&ctx->cq_timeouts);
timeout->target_seq = tail + off;
/* Update the last seq here in case io_flush_timeouts() hasn't.
* This is safe because ->completion_lock is held, and submissions
* and completions are never mixed in the same ->completion_lock section.
*/
ctx->cq_last_tm_flush = tail;
/*
* Insertion sort, ensuring the first entry in the list is always
* the one we need first.
*/
list_for_each_prev(entry, &ctx->timeout_list) {
struct io_timeout *nextt = list_entry(entry, struct io_timeout, list);
struct io_kiocb *nxt = cmd_to_io_kiocb(nextt);
if (io_is_timeout_noseq(nxt))
continue;
/* nxt.seq is behind @tail, otherwise would've been completed */
if (off >= nextt->target_seq - tail)
break;
}
add:
list_add(&timeout->list, entry);
data->timer.function = io_timeout_fn;
hrtimer_start(&data->timer, timespec64_to_ktime(data->ts), data->mode);
spin_unlock_irq(&ctx->timeout_lock);
return IOU_ISSUE_SKIP_COMPLETE;
}
void io_queue_linked_timeout(struct io_kiocb *req)
{
struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
struct io_ring_ctx *ctx = req->ctx;
spin_lock_irq(&ctx->timeout_lock);
/*
* If the back reference is NULL, then our linked request finished
* before we got a chance to setup the timer
*/
if (timeout->head) {
struct io_timeout_data *data = req->async_data;
data->timer.function = io_link_timeout_fn;
hrtimer_start(&data->timer, timespec64_to_ktime(data->ts),
data->mode);
list_add_tail(&timeout->list, &ctx->ltimeout_list);
}
spin_unlock_irq(&ctx->timeout_lock);
/* drop submission reference */
io_put_req(req);
}
static bool io_match_task(struct io_kiocb *head, struct task_struct *task,
bool cancel_all)
__must_hold(&req->ctx->timeout_lock)
{
struct io_kiocb *req;
if (task && head->task != task)
return false;
if (cancel_all)
return true;
io_for_each_link(req, head) {
if (req->flags & REQ_F_INFLIGHT)
return true;
}
return false;
}
/* Returns true if we found and killed one or more timeouts */
__cold bool io_kill_timeouts(struct io_ring_ctx *ctx, struct task_struct *tsk,
bool cancel_all)
{
struct io_timeout *timeout, *tmp;
int canceled = 0;
io_cq_lock(ctx);
spin_lock_irq(&ctx->timeout_lock);
list_for_each_entry_safe(timeout, tmp, &ctx->timeout_list, list) {
struct io_kiocb *req = cmd_to_io_kiocb(timeout);
if (io_match_task(req, tsk, cancel_all) &&
io_kill_timeout(req, -ECANCELED))
canceled++;
}
spin_unlock_irq(&ctx->timeout_lock);
io_cq_unlock_post(ctx);
return canceled != 0;
}