io_wq: add get/put_work handlers to io_wq_create()
For cancellation, we need to ensure that the work item stays valid for as long as ->cur_work is valid. Right now we can't safely dereference the work item even under the wqe->lock, because while the ->cur_work pointer will remain valid, the work could be completing and be freed in parallel. Only invoke ->get/put_work() on items we know that the caller queued themselves. Add IO_WQ_WORK_INTERNAL for io-wq to use, which is needed when we're queueing a flush item, for instance. Signed-off-by: Jens Axboe <axboe@kernel.dk>
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@@ -3822,6 +3822,20 @@ static int io_sqe_files_update(struct io_ring_ctx *ctx, void __user *arg,
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return done ? done : err;
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}
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static void io_put_work(struct io_wq_work *work)
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{
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struct io_kiocb *req = container_of(work, struct io_kiocb, work);
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io_put_req(req);
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}
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static void io_get_work(struct io_wq_work *work)
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{
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struct io_kiocb *req = container_of(work, struct io_kiocb, work);
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refcount_inc(&req->refs);
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}
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static int io_sq_offload_start(struct io_ring_ctx *ctx,
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struct io_uring_params *p)
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{
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@@ -3871,7 +3885,8 @@ static int io_sq_offload_start(struct io_ring_ctx *ctx,
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/* Do QD, or 4 * CPUS, whatever is smallest */
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concurrency = min(ctx->sq_entries, 4 * num_online_cpus());
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ctx->io_wq = io_wq_create(concurrency, ctx->sqo_mm, ctx->user);
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ctx->io_wq = io_wq_create(concurrency, ctx->sqo_mm, ctx->user,
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io_get_work, io_put_work);
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if (IS_ERR(ctx->io_wq)) {
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ret = PTR_ERR(ctx->io_wq);
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ctx->io_wq = NULL;
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