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io_uring/cancel: don't default to setting req->work.cancel_seq 

Just leave it unset by default, avoiding dipping into the last
cacheline (which is otherwise untouched) for the fast path of using
poll to drive networked traffic. Add a flag that tells us if the
sequence is valid or not, and then we can defer actually assigning
the flag and sequence until someone runs cancelations.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2024-01-28 20:11:55 -07:00
parent 4bcb982cce
commit 521223d7c2
5 changed files with 15 additions and 8 deletions
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3
include/linux/io_uring_types.h
View File

@ -463,6 +463,7 @@ enum {
REQ_F_SUPPORT_NOWAIT_BIT,
REQ_F_ISREG_BIT,
REQ_F_POLL_NO_LAZY_BIT,
REQ_F_CANCEL_SEQ_BIT,
/* not a real bit, just to check we're not overflowing the space */
__REQ_F_LAST_BIT,
@ -535,6 +536,8 @@ enum {
REQ_F_HASH_LOCKED = IO_REQ_FLAG(REQ_F_HASH_LOCKED_BIT),
/* don't use lazy poll wake for this request */
REQ_F_POLL_NO_LAZY = IO_REQ_FLAG(REQ_F_POLL_NO_LAZY_BIT),
/* cancel sequence is set and valid */
REQ_F_CANCEL_SEQ = IO_REQ_FLAG(REQ_F_CANCEL_SEQ_BIT),
};
typedef void (*io_req_tw_func_t)(struct io_kiocb *req, struct io_tw_state *ts);

3
io_uring/cancel.c
View File

@ -58,9 +58,8 @@ bool io_cancel_req_match(struct io_kiocb *req, struct io_cancel_data *cd)
return false;
if (cd->flags & IORING_ASYNC_CANCEL_ALL) {
check_seq:
if (cd->seq == req->work.cancel_seq)
if (io_cancel_match_sequence(req, cd->seq))
return false;
req->work.cancel_seq = cd->seq;
}
return true;

10
io_uring/cancel.h
View File

@ -25,4 +25,14 @@ void init_hash_table(struct io_hash_table *table, unsigned size);
int io_sync_cancel(struct io_ring_ctx *ctx, void __user *arg);
bool io_cancel_req_match(struct io_kiocb *req, struct io_cancel_data *cd);
static inline bool io_cancel_match_sequence(struct io_kiocb *req, int sequence)
{
if ((req->flags & REQ_F_CANCEL_SEQ) && sequence == req->work.cancel_seq)
return true;
req->flags |= REQ_F_CANCEL_SEQ;
req->work.cancel_seq = sequence;
return false;
}
#endif

1
io_uring/io_uring.c
View File

@ -463,7 +463,6 @@ static void io_prep_async_work(struct io_kiocb *req)
req->work.list.next = NULL;
req->work.flags = 0;
req->work.cancel_seq = atomic_read(&ctx->cancel_seq);
if (req->flags & REQ_F_FORCE_ASYNC)
req->work.flags |= IO_WQ_WORK_CONCURRENT;

6
io_uring/poll.c
View File

@ -588,10 +588,7 @@ static int __io_arm_poll_handler(struct io_kiocb *req,
struct io_poll_table *ipt, __poll_t mask,
unsigned issue_flags)
{
struct io_ring_ctx *ctx = req->ctx;
INIT_HLIST_NODE(&req->hash_node);
req->work.cancel_seq = atomic_read(&ctx->cancel_seq);
io_init_poll_iocb(poll, mask);
poll->file = req->file;
req->apoll_events = poll->events;
@ -818,9 +815,8 @@ static struct io_kiocb *io_poll_find(struct io_ring_ctx *ctx, bool poll_only,
if (poll_only && req->opcode != IORING_OP_POLL_ADD)
continue;
if (cd->flags & IORING_ASYNC_CANCEL_ALL) {
if (cd->seq == req->work.cancel_seq)
if (io_cancel_match_sequence(req, cd->seq))
continue;
req->work.cancel_seq = cd->seq;
}
*out_bucket = hb;
return req;