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io_uring/kbuf: flag partial buffer mappings

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A previous commit aborted mapping more for a non-incremental ring for
bundle peeking, but depending on where in the process this peeking
happened, it would not necessarily prevent a retry by the user. That can
create gaps in the received/read data.

Add struct buf_sel_arg->partial_map, which can pass this information
back. The networking side can then map that to internal state and use it
to gate retry as well.

Since this necessitates a new flag, change io_sr_msg->retry to a
retry_flags member, and store both the retry and partial map condition
in there.

Cc: stable@vger.kernel.org
Fixes: 26ec15e4b0 ("io_uring/kbuf: don't truncate end buffer for multiple buffer peeks")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2025-06-26 12:17:48 -06:00
parent 9a709b7e98
commit 178b8ff66f
3 changed files with 18 additions and 9 deletions
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1
io_uring/kbuf.c
View File

@ -271,6 +271,7 @@ static int io_ring_buffers_peek(struct io_kiocb *req, struct buf_sel_arg *arg,
if (len > arg->max_len) {
len = arg->max_len;
if (!(bl->flags & IOBL_INC)) {
arg->partial_map = 1;
if (iov != arg->iovs)
break;
buf->len = len;

3
io_uring/kbuf.h
View File

@ -58,7 +58,8 @@ struct buf_sel_arg {
size_t max_len;
unsigned short nr_iovs;
unsigned short mode;
unsigned buf_group;
unsigned short buf_group;
unsigned short partial_map;
};
void __user *io_buffer_select(struct io_kiocb *req, size_t *len,

23
io_uring/net.c
View File

@ -75,12 +75,17 @@ struct io_sr_msg {
u16 flags;
/* initialised and used only by !msg send variants */
u16 buf_group;
bool retry;
unsigned short retry_flags;
void __user *msg_control;
/* used only for send zerocopy */
struct io_kiocb *notif;
};
enum sr_retry_flags {
IO_SR_MSG_RETRY = 1,
IO_SR_MSG_PARTIAL_MAP = 2,
};
/*
* Number of times we'll try and do receives if there's more data. If we
* exceed this limit, then add us to the back of the queue and retry from
@ -187,7 +192,7 @@ static inline void io_mshot_prep_retry(struct io_kiocb *req,
req->flags &= ~REQ_F_BL_EMPTY;
sr->done_io = 0;
sr->retry = false;
sr->retry_flags = 0;
sr->len = 0; /* get from the provided buffer */
}
@ -397,7 +402,7 @@ int io_sendmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
sr->done_io = 0;
sr->retry = false;
sr->retry_flags = 0;
sr->len = READ_ONCE(sqe->len);
sr->flags = READ_ONCE(sqe->ioprio);
if (sr->flags & ~SENDMSG_FLAGS)
@ -751,7 +756,7 @@ int io_recvmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
sr->done_io = 0;
sr->retry = false;
sr->retry_flags = 0;
if (unlikely(sqe->file_index || sqe->addr2))
return -EINVAL;
@ -823,7 +828,7 @@ static inline bool io_recv_finish(struct io_kiocb *req, int *ret,
cflags |= io_put_kbufs(req, this_ret, io_bundle_nbufs(kmsg, this_ret),
issue_flags);
if (sr->retry)
if (sr->retry_flags & IO_SR_MSG_RETRY)
cflags = req->cqe.flags | (cflags & CQE_F_MASK);
/* bundle with no more immediate buffers, we're done */
if (req->flags & REQ_F_BL_EMPTY)
@ -832,12 +837,12 @@ static inline bool io_recv_finish(struct io_kiocb *req, int *ret,
* If more is available AND it was a full transfer, retry and
* append to this one
*/
if (!sr->retry && kmsg->msg.msg_inq > 1 && this_ret > 0 &&
if (!sr->retry_flags && kmsg->msg.msg_inq > 1 && this_ret > 0 &&
!iov_iter_count(&kmsg->msg.msg_iter)) {
req->cqe.flags = cflags & ~CQE_F_MASK;
sr->len = kmsg->msg.msg_inq;
sr->done_io += this_ret;
sr->retry = true;
sr->retry_flags |= IO_SR_MSG_RETRY;
return false;
}
} else {
@ -1082,6 +1087,8 @@ static int io_recv_buf_select(struct io_kiocb *req, struct io_async_msghdr *kmsg
kmsg->vec.iovec = arg.iovs;
req->flags |= REQ_F_NEED_CLEANUP;
}
if (arg.partial_map)
sr->retry_flags |= IO_SR_MSG_PARTIAL_MAP;
/* special case 1 vec, can be a fast path */
if (ret == 1) {
@ -1276,7 +1283,7 @@ int io_send_zc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
int ret;
zc->done_io = 0;
zc->retry = false;
zc->retry_flags = 0;
if (unlikely(READ_ONCE(sqe->__pad2[0]) || READ_ONCE(sqe->addr3)))
return -EINVAL;