linux/io_uring/notif.c
Pavel Begunkov 19352a1d39 io_uring/notif: disable LAZY_WAKE for linked notifs
Notifications may now be linked and thus a single tw can post multiple
CQEs, it's not safe to use LAZY_WAKE with them. Disable LAZY_WAKE for
now, if that'd prove to be a problem we can count them and pass the
expected number of CQEs into __io_req_task_work_add().

Fixes: 6fe4220912 ("io_uring/notif: implement notification stacking")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/0a5accdb7d2d0d27ebec14f8106e14e0192fae17.1714488419.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-04-30 13:06:27 -06:00

133 lines
3.2 KiB
C

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/net.h>
#include <linux/io_uring.h>
#include "io_uring.h"
#include "notif.h"
#include "rsrc.h"
static const struct ubuf_info_ops io_ubuf_ops;
static void io_notif_tw_complete(struct io_kiocb *notif, struct io_tw_state *ts)
{
struct io_notif_data *nd = io_notif_to_data(notif);
do {
notif = cmd_to_io_kiocb(nd);
lockdep_assert(refcount_read(&nd->uarg.refcnt) == 0);
if (unlikely(nd->zc_report) && (nd->zc_copied || !nd->zc_used))
notif->cqe.res |= IORING_NOTIF_USAGE_ZC_COPIED;
if (nd->account_pages && notif->ctx->user) {
__io_unaccount_mem(notif->ctx->user, nd->account_pages);
nd->account_pages = 0;
}
nd = nd->next;
io_req_task_complete(notif, ts);
} while (nd);
}
void io_tx_ubuf_complete(struct sk_buff *skb, struct ubuf_info *uarg,
bool success)
{
struct io_notif_data *nd = container_of(uarg, struct io_notif_data, uarg);
struct io_kiocb *notif = cmd_to_io_kiocb(nd);
unsigned tw_flags;
if (nd->zc_report) {
if (success && !nd->zc_used && skb)
WRITE_ONCE(nd->zc_used, true);
else if (!success && !nd->zc_copied)
WRITE_ONCE(nd->zc_copied, true);
}
if (!refcount_dec_and_test(&uarg->refcnt))
return;
if (nd->head != nd) {
io_tx_ubuf_complete(skb, &nd->head->uarg, success);
return;
}
tw_flags = nd->next ? 0 : IOU_F_TWQ_LAZY_WAKE;
notif->io_task_work.func = io_notif_tw_complete;
__io_req_task_work_add(notif, tw_flags);
}
static int io_link_skb(struct sk_buff *skb, struct ubuf_info *uarg)
{
struct io_notif_data *nd, *prev_nd;
struct io_kiocb *prev_notif, *notif;
struct ubuf_info *prev_uarg = skb_zcopy(skb);
nd = container_of(uarg, struct io_notif_data, uarg);
notif = cmd_to_io_kiocb(nd);
if (!prev_uarg) {
net_zcopy_get(&nd->uarg);
skb_zcopy_init(skb, &nd->uarg);
return 0;
}
/* handle it separately as we can't link a notif to itself */
if (unlikely(prev_uarg == &nd->uarg))
return 0;
/* we can't join two links together, just request a fresh skb */
if (unlikely(nd->head != nd || nd->next))
return -EEXIST;
/* don't mix zc providers */
if (unlikely(prev_uarg->ops != &io_ubuf_ops))
return -EEXIST;
prev_nd = container_of(prev_uarg, struct io_notif_data, uarg);
prev_notif = cmd_to_io_kiocb(nd);
/* make sure all noifications can be finished in the same task_work */
if (unlikely(notif->ctx != prev_notif->ctx ||
notif->task != prev_notif->task))
return -EEXIST;
nd->head = prev_nd->head;
nd->next = prev_nd->next;
prev_nd->next = nd;
net_zcopy_get(&nd->head->uarg);
return 0;
}
static const struct ubuf_info_ops io_ubuf_ops = {
.complete = io_tx_ubuf_complete,
.link_skb = io_link_skb,
};
struct io_kiocb *io_alloc_notif(struct io_ring_ctx *ctx)
__must_hold(&ctx->uring_lock)
{
struct io_kiocb *notif;
struct io_notif_data *nd;
if (unlikely(!io_alloc_req(ctx, &notif)))
return NULL;
notif->opcode = IORING_OP_NOP;
notif->flags = 0;
notif->file = NULL;
notif->task = current;
io_get_task_refs(1);
notif->rsrc_node = NULL;
nd = io_notif_to_data(notif);
nd->zc_report = false;
nd->account_pages = 0;
nd->next = NULL;
nd->head = nd;
nd->uarg.flags = IO_NOTIF_UBUF_FLAGS;
nd->uarg.ops = &io_ubuf_ops;
refcount_set(&nd->uarg.refcnt, 1);
return notif;
}