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io_uring: ensure IORING_REGISTER_IOWQ_MAX_WORKERS works with SQPOLL

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SQPOLL has a different thread doing submissions, we need to check for
that and use the right task context when updating the worker values.
Just hold the sqd->lock across the operation, this ensures that the
thread cannot go away while we poke at ->io_uring.

Link: https://github.com/axboe/liburing/issues/420
Fixes: 2e480058dd ("io-wq: provide a way to limit max number of workers")
Reported-by: Johannes Lundberg <johalun0@gmail.com>
Tested-by: Johannes Lundberg <johalun0@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2021-09-01 14:15:59 -06:00
parent 3146cba99a
commit fa84693b3c
1 changed files with 24 additions and 4 deletions
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28
fs/io_uring.c
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@ -10323,26 +10323,46 @@ 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)
{
struct io_uring_task *tctx = current->io_uring;
struct io_uring_task *tctx = NULL;
struct io_sq_data *sqd = NULL;
__u32 new_count[2];
int i, ret;
if (!tctx || !tctx->io_wq)
return -EINVAL;
if (copy_from_user(new_count, arg, sizeof(new_count)))
return -EFAULT;
for (i = 0; i < ARRAY_SIZE(new_count); i++)
if (new_count[i] > INT_MAX)
return -EINVAL;
if (ctx->flags & IORING_SETUP_SQPOLL) {
sqd = ctx->sq_data;
if (sqd) {
mutex_lock(&sqd->lock);
tctx = sqd->thread->io_uring;
}
} else {
tctx = current->io_uring;
}
ret = -EINVAL;
if (!tctx || !tctx->io_wq)
goto err;
ret = io_wq_max_workers(tctx->io_wq, new_count);
if (ret)
return ret;
goto err;
if (sqd)
mutex_unlock(&sqd->lock);
if (copy_to_user(arg, new_count, sizeof(new_count)))
return -EFAULT;
return 0;
err:
if (sqd)
mutex_unlock(&sqd->lock);
return ret;
}
static bool io_register_op_must_quiesce(int op)