linux/io_uring/io_uring.h
Jens Axboe 1658633c04 io_uring: ensure io_lockdep_assert_cq_locked() handles disabled rings
io_lockdep_assert_cq_locked() checks that locking is correctly done when
a CQE is posted. If the ring is setup in a disabled state with
IORING_SETUP_R_DISABLED, then ctx->submitter_task isn't assigned until
the ring is later enabled. We generally don't post CQEs in this state,
as no SQEs can be submitted. However it is possible to generate a CQE
if tagged resources are being updated. If this happens and PROVE_LOCKING
is enabled, then the locking check helper will dereference
ctx->submitter_task, which hasn't been set yet.

Fixup io_lockdep_assert_cq_locked() to handle this case correctly. While
at it, convert it to a static inline as well, so that generated line
offsets will actually reflect which condition failed, rather than just
the line offset for io_lockdep_assert_cq_locked() itself.

Reported-and-tested-by: syzbot+efc45d4e7ba6ab4ef1eb@syzkaller.appspotmail.com
Fixes: f26cc95935 ("io_uring: lockdep annotate CQ locking")
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-10-03 08:12:54 -06:00

395 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 {
/*
* A hint to not wake right away but delay until there are enough of
* tw's queued to match the number of CQEs the task is waiting for.
*
* Must not be used wirh requests generating more than one CQE.
* It's also ignored unless IORING_SETUP_DEFER_TASKRUN is set.
*/
IOU_F_TWQ_LAZY_WAKE = 1,
};
enum {
IOU_OK = 0,
IOU_ISSUE_SKIP_COMPLETE = -EIOCBQUEUED,
/*
* 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_is_uring_fops(struct file *file);
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);
#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;
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