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| author | Jens Axboe <axboe@kernel.dk> | 2023-12-13 18:58:15 +0300 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2023-12-13 18:58:15 +0300 |
| commit | 595e52284d24adc376890d3fc93bdca4707d9aca (patch) | |
| tree | 7648aeef9e7ca87c0e2b9be537cf68dee084478d /include | |
| parent | 705318a99a138c29a512a72c3e0043b3cd7f55f4 (diff) | |
| download | linux-595e52284d24adc376890d3fc93bdca4707d9aca.tar.xz | |
io_uring/poll: don't enable lazy wake for POLLEXCLUSIVE
There are a few quirks around using lazy wake for poll unconditionally,
and one of them is related the EPOLLEXCLUSIVE. Those may trigger
exclusive wakeups, which wake a limited number of entries in the wait
queue. If that wake number is less than the number of entries someone is
waiting for (and that someone is also using DEFER_TASKRUN), then we can
get stuck waiting for more entries while we should be processing the ones
we already got.
If we're doing exclusive poll waits, flag the request as not being
compatible with lazy wakeups.
Reported-by: Pavel Begunkov <asml.silence@gmail.com>
Fixes: 6ce4a93dbb5b ("io_uring/poll: use IOU_F_TWQ_LAZY_WAKE for wakeups")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/io_uring_types.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h index 805bb635cdf5..239a4f68801b 100644 --- a/include/linux/io_uring_types.h +++ b/include/linux/io_uring_types.h @@ -434,6 +434,7 @@ enum { /* keep async read/write and isreg together and in order */ REQ_F_SUPPORT_NOWAIT_BIT, REQ_F_ISREG_BIT, + REQ_F_POLL_NO_LAZY_BIT, /* not a real bit, just to check we're not overflowing the space */ __REQ_F_LAST_BIT, @@ -501,6 +502,8 @@ enum { REQ_F_CLEAR_POLLIN = BIT(REQ_F_CLEAR_POLLIN_BIT), /* hashed into ->cancel_hash_locked, protected by ->uring_lock */ REQ_F_HASH_LOCKED = BIT(REQ_F_HASH_LOCKED_BIT), + /* don't use lazy poll wake for this request */ + REQ_F_POLL_NO_LAZY = BIT(REQ_F_POLL_NO_LAZY_BIT), }; typedef void (*io_req_tw_func_t)(struct io_kiocb *req, struct io_tw_state *ts); |