linux-stable/io_uring/futex.c
Jens Axboe 414d0f45c3 io_uring/alloc_cache: switch to array based caching
Currently lists are being used to manage this, but best practice is
usually to have these in an array instead as that it cheaper to manage.

Outside of that detail, games are also played with KASAN as the list
is inside the cached entry itself.

Finally, all users of this need a struct io_cache_entry embedded in
their struct, which is union'ized with something else in there that
isn't used across the free -> realloc cycle.

Get rid of all of that, and simply have it be an array. This will not
change the memory used, as we're just trading an 8-byte member entry
for the per-elem array size.

This reduces the overhead of the recycled allocations, and it reduces
the amount of code code needed to support recycling to about half of
what it currently is.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-04-15 08:10:25 -06:00

381 lines
9.3 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/io_uring.h>
#include <uapi/linux/io_uring.h>
#include "../kernel/futex/futex.h"
#include "io_uring.h"
#include "alloc_cache.h"
#include "futex.h"
struct io_futex {
struct file *file;
union {
u32 __user *uaddr;
struct futex_waitv __user *uwaitv;
};
unsigned long futex_val;
unsigned long futex_mask;
unsigned long futexv_owned;
u32 futex_flags;
unsigned int futex_nr;
bool futexv_unqueued;
};
struct io_futex_data {
struct futex_q q;
struct io_kiocb *req;
};
#define IO_FUTEX_ALLOC_CACHE_MAX 32
bool io_futex_cache_init(struct io_ring_ctx *ctx)
{
return io_alloc_cache_init(&ctx->futex_cache, IO_FUTEX_ALLOC_CACHE_MAX,
sizeof(struct io_futex_data));
}
void io_futex_cache_free(struct io_ring_ctx *ctx)
{
io_alloc_cache_free(&ctx->futex_cache, kfree);
}
static void __io_futex_complete(struct io_kiocb *req, struct io_tw_state *ts)
{
req->async_data = NULL;
hlist_del_init(&req->hash_node);
io_req_task_complete(req, ts);
}
static void io_futex_complete(struct io_kiocb *req, struct io_tw_state *ts)
{
struct io_futex_data *ifd = req->async_data;
struct io_ring_ctx *ctx = req->ctx;
io_tw_lock(ctx, ts);
if (!io_alloc_cache_put(&ctx->futex_cache, ifd))
kfree(ifd);
__io_futex_complete(req, ts);
}
static void io_futexv_complete(struct io_kiocb *req, struct io_tw_state *ts)
{
struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
struct futex_vector *futexv = req->async_data;
io_tw_lock(req->ctx, ts);
if (!iof->futexv_unqueued) {
int res;
res = futex_unqueue_multiple(futexv, iof->futex_nr);
if (res != -1)
io_req_set_res(req, res, 0);
}
kfree(req->async_data);
req->flags &= ~REQ_F_ASYNC_DATA;
__io_futex_complete(req, ts);
}
static bool io_futexv_claim(struct io_futex *iof)
{
if (test_bit(0, &iof->futexv_owned) ||
test_and_set_bit_lock(0, &iof->futexv_owned))
return false;
return true;
}
static bool __io_futex_cancel(struct io_ring_ctx *ctx, struct io_kiocb *req)
{
/* futex wake already done or in progress */
if (req->opcode == IORING_OP_FUTEX_WAIT) {
struct io_futex_data *ifd = req->async_data;
if (!futex_unqueue(&ifd->q))
return false;
req->io_task_work.func = io_futex_complete;
} else {
struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
if (!io_futexv_claim(iof))
return false;
req->io_task_work.func = io_futexv_complete;
}
hlist_del_init(&req->hash_node);
io_req_set_res(req, -ECANCELED, 0);
io_req_task_work_add(req);
return true;
}
int io_futex_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd,
unsigned int issue_flags)
{
struct hlist_node *tmp;
struct io_kiocb *req;
int nr = 0;
if (cd->flags & (IORING_ASYNC_CANCEL_FD|IORING_ASYNC_CANCEL_FD_FIXED))
return -ENOENT;
io_ring_submit_lock(ctx, issue_flags);
hlist_for_each_entry_safe(req, tmp, &ctx->futex_list, hash_node) {
if (req->cqe.user_data != cd->data &&
!(cd->flags & IORING_ASYNC_CANCEL_ANY))
continue;
if (__io_futex_cancel(ctx, req))
nr++;
if (!(cd->flags & IORING_ASYNC_CANCEL_ALL))
break;
}
io_ring_submit_unlock(ctx, issue_flags);
if (nr)
return nr;
return -ENOENT;
}
bool io_futex_remove_all(struct io_ring_ctx *ctx, struct task_struct *task,
bool cancel_all)
{
struct hlist_node *tmp;
struct io_kiocb *req;
bool found = false;
lockdep_assert_held(&ctx->uring_lock);
hlist_for_each_entry_safe(req, tmp, &ctx->futex_list, hash_node) {
if (!io_match_task_safe(req, task, cancel_all))
continue;
hlist_del_init(&req->hash_node);
__io_futex_cancel(ctx, req);
found = true;
}
return found;
}
int io_futex_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
u32 flags;
if (unlikely(sqe->len || sqe->futex_flags || sqe->buf_index ||
sqe->file_index))
return -EINVAL;
iof->uaddr = u64_to_user_ptr(READ_ONCE(sqe->addr));
iof->futex_val = READ_ONCE(sqe->addr2);
iof->futex_mask = READ_ONCE(sqe->addr3);
flags = READ_ONCE(sqe->fd);
if (flags & ~FUTEX2_VALID_MASK)
return -EINVAL;
iof->futex_flags = futex2_to_flags(flags);
if (!futex_flags_valid(iof->futex_flags))
return -EINVAL;
if (!futex_validate_input(iof->futex_flags, iof->futex_val) ||
!futex_validate_input(iof->futex_flags, iof->futex_mask))
return -EINVAL;
return 0;
}
static void io_futex_wakev_fn(struct wake_q_head *wake_q, struct futex_q *q)
{
struct io_kiocb *req = q->wake_data;
struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
if (!io_futexv_claim(iof))
return;
if (unlikely(!__futex_wake_mark(q)))
return;
io_req_set_res(req, 0, 0);
req->io_task_work.func = io_futexv_complete;
io_req_task_work_add(req);
}
int io_futexv_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
{
struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
struct futex_vector *futexv;
int ret;
/* No flags or mask supported for waitv */
if (unlikely(sqe->fd || sqe->buf_index || sqe->file_index ||
sqe->addr2 || sqe->futex_flags || sqe->addr3))
return -EINVAL;
iof->uaddr = u64_to_user_ptr(READ_ONCE(sqe->addr));
iof->futex_nr = READ_ONCE(sqe->len);
if (!iof->futex_nr || iof->futex_nr > FUTEX_WAITV_MAX)
return -EINVAL;
futexv = kcalloc(iof->futex_nr, sizeof(*futexv), GFP_KERNEL);
if (!futexv)
return -ENOMEM;
ret = futex_parse_waitv(futexv, iof->uwaitv, iof->futex_nr,
io_futex_wakev_fn, req);
if (ret) {
kfree(futexv);
return ret;
}
iof->futexv_owned = 0;
iof->futexv_unqueued = 0;
req->flags |= REQ_F_ASYNC_DATA;
req->async_data = futexv;
return 0;
}
static void io_futex_wake_fn(struct wake_q_head *wake_q, struct futex_q *q)
{
struct io_futex_data *ifd = container_of(q, struct io_futex_data, q);
struct io_kiocb *req = ifd->req;
if (unlikely(!__futex_wake_mark(q)))
return;
io_req_set_res(req, 0, 0);
req->io_task_work.func = io_futex_complete;
io_req_task_work_add(req);
}
static struct io_futex_data *io_alloc_ifd(struct io_ring_ctx *ctx)
{
struct io_futex_data *ifd;
ifd = io_alloc_cache_get(&ctx->futex_cache);
if (ifd)
return ifd;
return kmalloc(sizeof(struct io_futex_data), GFP_NOWAIT);
}
int io_futexv_wait(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
struct futex_vector *futexv = req->async_data;
struct io_ring_ctx *ctx = req->ctx;
int ret, woken = -1;
io_ring_submit_lock(ctx, issue_flags);
ret = futex_wait_multiple_setup(futexv, iof->futex_nr, &woken);
/*
* Error case, ret is < 0. Mark the request as failed.
*/
if (unlikely(ret < 0)) {
io_ring_submit_unlock(ctx, issue_flags);
req_set_fail(req);
io_req_set_res(req, ret, 0);
kfree(futexv);
req->async_data = NULL;
req->flags &= ~REQ_F_ASYNC_DATA;
return IOU_OK;
}
/*
* 0 return means that we successfully setup the waiters, and that
* nobody triggered a wakeup while we were doing so. If the wakeup
* happened post setup, the task_work will be run post this issue and
* under the submission lock. 1 means We got woken while setting up,
* let that side do the completion. Note that
* futex_wait_multiple_setup() will have unqueued all the futexes in
* this case. Mark us as having done that already, since this is
* different from normal wakeup.
*/
if (!ret) {
/*
* If futex_wait_multiple_setup() returns 0 for a
* successful setup, then the task state will not be
* runnable. This is fine for the sync syscall, as
* it'll be blocking unless we already got one of the
* futexes woken, but it obviously won't work for an
* async invocation. Mark us runnable again.
*/
__set_current_state(TASK_RUNNING);
hlist_add_head(&req->hash_node, &ctx->futex_list);
} else {
iof->futexv_unqueued = 1;
if (woken != -1)
io_req_set_res(req, woken, 0);
}
io_ring_submit_unlock(ctx, issue_flags);
return IOU_ISSUE_SKIP_COMPLETE;
}
int io_futex_wait(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
struct io_ring_ctx *ctx = req->ctx;
struct io_futex_data *ifd = NULL;
struct futex_hash_bucket *hb;
int ret;
if (!iof->futex_mask) {
ret = -EINVAL;
goto done;
}
io_ring_submit_lock(ctx, issue_flags);
ifd = io_alloc_ifd(ctx);
if (!ifd) {
ret = -ENOMEM;
goto done_unlock;
}
req->async_data = ifd;
ifd->q = futex_q_init;
ifd->q.bitset = iof->futex_mask;
ifd->q.wake = io_futex_wake_fn;
ifd->req = req;
ret = futex_wait_setup(iof->uaddr, iof->futex_val, iof->futex_flags,
&ifd->q, &hb);
if (!ret) {
hlist_add_head(&req->hash_node, &ctx->futex_list);
io_ring_submit_unlock(ctx, issue_flags);
futex_queue(&ifd->q, hb);
return IOU_ISSUE_SKIP_COMPLETE;
}
done_unlock:
io_ring_submit_unlock(ctx, issue_flags);
done:
if (ret < 0)
req_set_fail(req);
io_req_set_res(req, ret, 0);
kfree(ifd);
return IOU_OK;
}
int io_futex_wake(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_futex *iof = io_kiocb_to_cmd(req, struct io_futex);
int ret;
/*
* Strict flags - ensure that waking 0 futexes yields a 0 result.
* See commit 43adf8449510 ("futex: FLAGS_STRICT") for details.
*/
ret = futex_wake(iof->uaddr, FLAGS_STRICT | iof->futex_flags,
iof->futex_val, iof->futex_mask);
if (ret < 0)
req_set_fail(req);
io_req_set_res(req, ret, 0);
return IOU_OK;
}