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io_uring: cleanup conditional submit locking
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Refactor io_ring_submit_[un]lock(), make it accept issue_flags and
remove manual IO_URING_F_UNLOCKED checks. It also allows us to place
lockdep annotations inside instead of sprinkling them in a bunch of
places. There is only one user that doesn't fit now, so hand code
locking in __io_rsrc_put_work().

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e55c2c06767676a801252e8094c9ab09912487a4.1648209006.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Pavel Begunkov authored and Jens Axboe committed Apr 24, 2022
1 parent d487b43 commit f892963
Showing 1 changed file with 41 additions and 54 deletions.
95 changes: 41 additions & 54 deletions fs/io_uring.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1223,6 +1223,26 @@ struct sock *io_uring_get_socket(struct file *file)
}
EXPORT_SYMBOL(io_uring_get_socket);

static 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 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_tw_lock(struct io_ring_ctx *ctx, bool *locked)
{
if (!*locked) {
Expand Down Expand Up @@ -1420,19 +1440,15 @@ static void io_kbuf_recycle(struct io_kiocb *req, unsigned issue_flags)
if (req->flags & REQ_F_PARTIAL_IO)
return;

if (issue_flags & IO_URING_F_UNLOCKED)
mutex_lock(&ctx->uring_lock);

lockdep_assert_held(&ctx->uring_lock);
io_ring_submit_lock(ctx, issue_flags);

buf = req->kbuf;
bl = io_buffer_get_list(ctx, buf->bgid);
list_add(&buf->list, &bl->buf_list);
req->flags &= ~REQ_F_BUFFER_SELECTED;
req->kbuf = NULL;

if (issue_flags & IO_URING_F_UNLOCKED)
mutex_unlock(&ctx->uring_lock);
io_ring_submit_unlock(ctx, issue_flags);
}

static bool io_match_task(struct io_kiocb *head, struct task_struct *task,
Expand Down Expand Up @@ -3309,24 +3325,6 @@ static int io_import_fixed(struct io_kiocb *req, int rw, struct iov_iter *iter,
return __io_import_fixed(req, rw, iter, imu);
}

static void io_ring_submit_unlock(struct io_ring_ctx *ctx, bool needs_lock)
{
if (needs_lock)
mutex_unlock(&ctx->uring_lock);
}

static void io_ring_submit_lock(struct io_ring_ctx *ctx, bool needs_lock)
{
/*
* "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 (needs_lock)
mutex_lock(&ctx->uring_lock);
}

static void io_buffer_add_list(struct io_ring_ctx *ctx,
struct io_buffer_list *bl, unsigned int bgid)
{
Expand All @@ -3342,16 +3340,13 @@ static struct io_buffer *io_buffer_select(struct io_kiocb *req, size_t *len,
int bgid, unsigned int issue_flags)
{
struct io_buffer *kbuf = req->kbuf;
bool needs_lock = issue_flags & IO_URING_F_UNLOCKED;
struct io_ring_ctx *ctx = req->ctx;
struct io_buffer_list *bl;

if (req->flags & REQ_F_BUFFER_SELECTED)
return kbuf;

io_ring_submit_lock(ctx, needs_lock);

lockdep_assert_held(&ctx->uring_lock);
io_ring_submit_lock(req->ctx, issue_flags);

bl = io_buffer_get_list(ctx, bgid);
if (bl && !list_empty(&bl->buf_list)) {
Expand All @@ -3365,7 +3360,7 @@ static struct io_buffer *io_buffer_select(struct io_kiocb *req, size_t *len,
kbuf = ERR_PTR(-ENOBUFS);
}

io_ring_submit_unlock(req->ctx, needs_lock);
io_ring_submit_unlock(req->ctx, issue_flags);
return kbuf;
}

Expand Down Expand Up @@ -4734,11 +4729,8 @@ static int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags)
struct io_ring_ctx *ctx = req->ctx;
struct io_buffer_list *bl;
int ret = 0;
bool needs_lock = issue_flags & IO_URING_F_UNLOCKED;

io_ring_submit_lock(ctx, needs_lock);

lockdep_assert_held(&ctx->uring_lock);
io_ring_submit_lock(ctx, issue_flags);

ret = -ENOENT;
bl = io_buffer_get_list(ctx, p->bgid);
Expand All @@ -4749,7 +4741,7 @@ static int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags)

/* complete before unlock, IOPOLL may need the lock */
__io_req_complete(req, issue_flags, ret, 0);
io_ring_submit_unlock(ctx, needs_lock);
io_ring_submit_unlock(ctx, issue_flags);
return 0;
}

Expand Down Expand Up @@ -4863,11 +4855,8 @@ static int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags)
struct io_ring_ctx *ctx = req->ctx;
struct io_buffer_list *bl;
int ret = 0;
bool needs_lock = issue_flags & IO_URING_F_UNLOCKED;

io_ring_submit_lock(ctx, needs_lock);

lockdep_assert_held(&ctx->uring_lock);
io_ring_submit_lock(ctx, issue_flags);

bl = io_buffer_get_list(ctx, p->bgid);
if (unlikely(!bl)) {
Expand All @@ -4885,7 +4874,7 @@ static int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags)
req_set_fail(req);
/* complete before unlock, IOPOLL may need the lock */
__io_req_complete(req, issue_flags, ret, 0);
io_ring_submit_unlock(ctx, needs_lock);
io_ring_submit_unlock(ctx, issue_flags);
return 0;
}

Expand Down Expand Up @@ -6787,7 +6776,6 @@ static int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_ring_ctx *ctx = req->ctx;
u64 sqe_addr = req->cancel.addr;
bool needs_lock = issue_flags & IO_URING_F_UNLOCKED;
struct io_tctx_node *node;
int ret;

Expand All @@ -6796,7 +6784,7 @@ static int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags)
goto done;

/* slow path, try all io-wq's */
io_ring_submit_lock(ctx, needs_lock);
io_ring_submit_lock(ctx, issue_flags);
ret = -ENOENT;
list_for_each_entry(node, &ctx->tctx_list, ctx_node) {
struct io_uring_task *tctx = node->task->io_uring;
Expand All @@ -6805,7 +6793,7 @@ static int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags)
if (ret != -ENOENT)
break;
}
io_ring_submit_unlock(ctx, needs_lock);
io_ring_submit_unlock(ctx, issue_flags);
done:
if (ret < 0)
req_set_fail(req);
Expand All @@ -6832,7 +6820,6 @@ static int io_rsrc_update_prep(struct io_kiocb *req,
static int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_ring_ctx *ctx = req->ctx;
bool needs_lock = issue_flags & IO_URING_F_UNLOCKED;
struct io_uring_rsrc_update2 up;
int ret;

Expand All @@ -6843,10 +6830,10 @@ static int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
up.resv = 0;
up.resv2 = 0;

io_ring_submit_lock(ctx, needs_lock);
io_ring_submit_lock(ctx, issue_flags);
ret = __io_register_rsrc_update(ctx, IORING_RSRC_FILE,
&up, req->rsrc_update.nr_args);
io_ring_submit_unlock(ctx, needs_lock);
io_ring_submit_unlock(ctx, issue_flags);

if (ret < 0)
req_set_fail(req);
Expand Down Expand Up @@ -8772,15 +8759,17 @@ static void __io_rsrc_put_work(struct io_rsrc_node *ref_node)
list_del(&prsrc->list);

if (prsrc->tag) {
bool lock_ring = ctx->flags & IORING_SETUP_IOPOLL;
if (ctx->flags & IORING_SETUP_IOPOLL)
mutex_lock(&ctx->uring_lock);

io_ring_submit_lock(ctx, lock_ring);
spin_lock(&ctx->completion_lock);
io_fill_cqe_aux(ctx, prsrc->tag, 0, 0);
io_commit_cqring(ctx);
spin_unlock(&ctx->completion_lock);
io_cqring_ev_posted(ctx);
io_ring_submit_unlock(ctx, lock_ring);

if (ctx->flags & IORING_SETUP_IOPOLL)
mutex_unlock(&ctx->uring_lock);
}

rsrc_data->do_put(ctx, prsrc);
Expand Down Expand Up @@ -8956,12 +8945,11 @@ static int io_install_fixed_file(struct io_kiocb *req, struct file *file,
unsigned int issue_flags, u32 slot_index)
{
struct io_ring_ctx *ctx = req->ctx;
bool needs_lock = issue_flags & IO_URING_F_UNLOCKED;
bool needs_switch = false;
struct io_fixed_file *file_slot;
int ret = -EBADF;

io_ring_submit_lock(ctx, needs_lock);
io_ring_submit_lock(ctx, issue_flags);
if (file->f_op == &io_uring_fops)
goto err;
ret = -ENXIO;
Expand Down Expand Up @@ -9002,7 +8990,7 @@ static int io_install_fixed_file(struct io_kiocb *req, struct file *file,
err:
if (needs_switch)
io_rsrc_node_switch(ctx, ctx->file_data);
io_ring_submit_unlock(ctx, needs_lock);
io_ring_submit_unlock(ctx, issue_flags);
if (ret)
fput(file);
return ret;
Expand All @@ -9012,12 +9000,11 @@ static int io_close_fixed(struct io_kiocb *req, unsigned int issue_flags)
{
unsigned int offset = req->close.file_slot - 1;
struct io_ring_ctx *ctx = req->ctx;
bool needs_lock = issue_flags & IO_URING_F_UNLOCKED;
struct io_fixed_file *file_slot;
struct file *file;
int ret;

io_ring_submit_lock(ctx, needs_lock);
io_ring_submit_lock(ctx, issue_flags);
ret = -ENXIO;
if (unlikely(!ctx->file_data))
goto out;
Expand All @@ -9043,7 +9030,7 @@ static int io_close_fixed(struct io_kiocb *req, unsigned int issue_flags)
io_rsrc_node_switch(ctx, ctx->file_data);
ret = 0;
out:
io_ring_submit_unlock(ctx, needs_lock);
io_ring_submit_unlock(ctx, issue_flags);
return ret;
}

Expand Down

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