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| author | Pavel Begunkov <asml.silence@gmail.com> | 2021-10-21 13:20:29 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-10-21 11:19:38 -0600 |
| commit | b22fa62a35d7f2029d757a518d78041822b7c7c1 (patch) | |
| tree | 610af96d64a830b4b5fae86a0f4cffd692a85ad8 /fs | |
| parent | 4ea672ab694c23886b52e97cee10dea056e43e62 (diff) | |
| download | lwn-b22fa62a35d7f2029d757a518d78041822b7c7c1.tar.gz lwn-b22fa62a35d7f2029d757a518d78041822b7c7c1.zip | |
io_uring: apply worker limits to previous users
Another change to the API io-wq worker limitation API added in 5.15,
apply the limit to all prior users that already registered a tctx. It
may be confusing as it's now, in particular the change covers the
following 2 cases:
TASK1 | TASK2
_________________________________________________
ring = create() |
| limit_iowq_workers()
*not limited* |
TASK1 | TASK2
_________________________________________________
ring = create() |
| issue_requests()
limit_iowq_workers() |
| *not limited*
A note on locking, it's safe to traverse ->tctx_list as we hold
->uring_lock, but do that after dropping sqd->lock to avoid possible
problems. It's also safe to access tctx->io_wq there because tasks
kill it only after removing themselves from tctx_list, see
io_uring_cancel_generic() -> io_uring_clean_tctx()
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/d6e09ecc3545e4dc56e43c906ee3d71b7ae21bed.1634818641.git.asml.silence@gmail.com
Reviewed-by: Hao Xu <haoxu@linux.alibaba.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/io_uring.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index d5cc103224f1..bc18af5e0a93 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -10649,7 +10649,9 @@ static int io_unregister_iowq_aff(struct io_ring_ctx *ctx) static int io_register_iowq_max_workers(struct io_ring_ctx *ctx, void __user *arg) + __must_hold(&ctx->uring_lock) { + struct io_tctx_node *node; struct io_uring_task *tctx = NULL; struct io_sq_data *sqd = NULL; __u32 new_count[2]; @@ -10702,6 +10704,22 @@ static int io_register_iowq_max_workers(struct io_ring_ctx *ctx, if (copy_to_user(arg, new_count, sizeof(new_count))) return -EFAULT; + /* that's it for SQPOLL, only the SQPOLL task creates requests */ + if (sqd) + return 0; + + /* now propagate the restriction to all registered users */ + list_for_each_entry(node, &ctx->tctx_list, ctx_node) { + struct io_uring_task *tctx = node->task->io_uring; + + if (WARN_ON_ONCE(!tctx->io_wq)) + continue; + + for (i = 0; i < ARRAY_SIZE(new_count); i++) + new_count[i] = ctx->iowq_limits[i]; + /* ignore errors, it always returns zero anyway */ + (void)io_wq_max_workers(tctx->io_wq, new_count); + } return 0; err: if (sqd) { |