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io_uring: get rid of double locking 

We don't need to take both uring_locks at once, msg_ring can be split in
two parts, first getting a file from the filetable of the first ring and
then installing it into the second one.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/a80ecc2bc99c3b3f2cf20015d618b7c51419a797.1670384893.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2022-12-07 03:53:34 +00:00 committed by Jens Axboe
parent 77e443ab29
commit 11373026f2
3 changed files with 52 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

83
io_uring/msg_ring.c
View File

@ -15,6 +15,7 @@
struct io_msg {
struct file *file;
struct file *src_file;
u64 user_data;
u32 len;
u32 cmd;
@ -23,6 +24,17 @@ struct io_msg {
u32 flags;
};
void io_msg_ring_cleanup(struct io_kiocb *req)
{
struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
if (WARN_ON_ONCE(!msg->src_file))
return;
fput(msg->src_file);
msg->src_file = NULL;
}
static int io_msg_ring_data(struct io_kiocb *req)
{
struct io_ring_ctx *target_ctx = req->file->private_data;
@ -37,17 +49,13 @@ static int io_msg_ring_data(struct io_kiocb *req)
return -EOVERFLOW;
}
static void io_double_unlock_ctx(struct io_ring_ctx *ctx,
struct io_ring_ctx *octx,
static void io_double_unlock_ctx(struct io_ring_ctx *octx,
unsigned int issue_flags)
{
if (issue_flags & IO_URING_F_UNLOCKED)
mutex_unlock(&ctx->uring_lock);
mutex_unlock(&octx->uring_lock);
}
static int io_double_lock_ctx(struct io_ring_ctx *ctx,
struct io_ring_ctx *octx,
static int io_double_lock_ctx(struct io_ring_ctx *octx,
unsigned int issue_flags)
{
/*
@ -60,17 +68,28 @@ static int io_double_lock_ctx(struct io_ring_ctx *ctx,
return -EAGAIN;
return 0;
}
/* Always grab smallest value ctx first. We know ctx != octx. */
if (ctx < octx) {
mutex_lock(&ctx->uring_lock);
mutex_lock(&octx->uring_lock);
} else {
mutex_lock(&octx->uring_lock);
mutex_lock(&ctx->uring_lock);
return 0;
}
return 0;
static struct file *io_msg_grab_file(struct io_kiocb *req, unsigned int issue_flags)
{
struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
struct io_ring_ctx *ctx = req->ctx;
struct file *file = NULL;
unsigned long file_ptr;
int idx = msg->src_fd;
io_ring_submit_lock(ctx, issue_flags);
if (likely(idx < ctx->nr_user_files)) {
idx = array_index_nospec(idx, ctx->nr_user_files);
file_ptr = io_fixed_file_slot(&ctx->file_table, idx)->file_ptr;
file = (struct file *) (file_ptr & FFS_MASK);
if (file)
get_file(file);
}
io_ring_submit_unlock(ctx, issue_flags);
return file;
}
static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags)
@ -78,34 +97,27 @@ static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags)
struct io_ring_ctx *target_ctx = req->file->private_data;
struct io_msg *msg = io_kiocb_to_cmd(req, struct io_msg);
struct io_ring_ctx *ctx = req->ctx;
unsigned long file_ptr;
struct file *src_file;
struct file *src_file = msg->src_file;
int ret;
if (target_ctx == ctx)
return -EINVAL;
if (!src_file) {
src_file = io_msg_grab_file(req, issue_flags);
if (!src_file)
return -EBADF;
msg->src_file = src_file;
req->flags |= REQ_F_NEED_CLEANUP;
}
ret = io_double_lock_ctx(ctx, target_ctx, issue_flags);
if (unlikely(ret))
return ret;
ret = -EBADF;
if (unlikely(msg->src_fd >= ctx->nr_user_files))
goto out_unlock;
msg->src_fd = array_index_nospec(msg->src_fd, ctx->nr_user_files);
file_ptr = io_fixed_file_slot(&ctx->file_table, msg->src_fd)->file_ptr;
if (!file_ptr)
goto out_unlock;
src_file = (struct file *) (file_ptr & FFS_MASK);
get_file(src_file);
if (unlikely(io_double_lock_ctx(target_ctx, issue_flags)))
return -EAGAIN;
ret = __io_fixed_fd_install(target_ctx, src_file, msg->dst_fd);
if (ret < 0) {
fput(src_file);
if (ret < 0)
goto out_unlock;
}
msg->src_file = NULL;
req->flags &= ~REQ_F_NEED_CLEANUP;
if (msg->flags & IORING_MSG_RING_CQE_SKIP)
goto out_unlock;
@ -119,7 +131,7 @@ static int io_msg_send_fd(struct io_kiocb *req, unsigned int issue_flags)
if (!io_post_aux_cqe(target_ctx, msg->user_data, msg->len, 0))
ret = -EOVERFLOW;
out_unlock:
io_double_unlock_ctx(ctx, target_ctx, issue_flags);
io_double_unlock_ctx(target_ctx, issue_flags);
return ret;
}
@ -130,6 +142,7 @@ int io_msg_ring_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
if (unlikely(sqe->buf_index || sqe->personality))
return -EINVAL;
msg->src_file = NULL;
msg->user_data = READ_ONCE(sqe->off);
msg->len = READ_ONCE(sqe->len);
msg->cmd = READ_ONCE(sqe->addr);

1
io_uring/msg_ring.h
View File

@ -2,3 +2,4 @@
int io_msg_ring_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
int io_msg_ring(struct io_kiocb *req, unsigned int issue_flags);
void io_msg_ring_cleanup(struct io_kiocb *req);

1
io_uring/opdef.c
View File

@ -445,6 +445,7 @@ const struct io_op_def io_op_defs[] = {
.name = "MSG_RING",
.prep = io_msg_ring_prep,
.issue = io_msg_ring,
.cleanup = io_msg_ring_cleanup,
},
[IORING_OP_FSETXATTR] = {
.needs_file = 1,