From f660fd2ca15a3743f65f6110ae60d5b80500d856 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 16 May 2025 13:39:32 -0600 Subject: [PATCH] io_uring: add new helpers for posting overflows Add two helpers, one for posting overflows for lockless_cq rings, and one for non-lockless_cq rings. The former can allocate sanely with GFP_KERNEL, but needs to grab the completion lock for posting, while the latter must do non-sleeping allocs as it already holds the completion lock. While at it, mark the overflow handling functions as __cold as well, as they should not generally be called during normal operations of the ring. Reviewed-by: Caleb Sander Mateos Signed-off-by: Jens Axboe --- io_uring/io_uring.c | 50 ++++++++++++++++++++++++++------------------- 1 file changed, 29 insertions(+), 21 deletions(-) diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index 4081ffd890af..3c4a9561941f 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -697,8 +697,8 @@ static __cold void io_uring_drop_tctx_refs(struct task_struct *task) } } -static bool io_cqring_add_overflow(struct io_ring_ctx *ctx, - struct io_overflow_cqe *ocqe) +static __cold bool io_cqring_add_overflow(struct io_ring_ctx *ctx, + struct io_overflow_cqe *ocqe) { lockdep_assert_held(&ctx->completion_lock); @@ -813,6 +813,27 @@ static inline struct io_cqe io_init_cqe(u64 user_data, s32 res, u32 cflags) return (struct io_cqe) { .user_data = user_data, .res = res, .flags = cflags }; } +static __cold void io_cqe_overflow(struct io_ring_ctx *ctx, struct io_cqe *cqe, + struct io_big_cqe *big_cqe) +{ + struct io_overflow_cqe *ocqe; + + ocqe = io_alloc_ocqe(ctx, cqe, big_cqe, GFP_KERNEL); + spin_lock(&ctx->completion_lock); + io_cqring_add_overflow(ctx, ocqe); + spin_unlock(&ctx->completion_lock); +} + +static __cold bool io_cqe_overflow_locked(struct io_ring_ctx *ctx, + struct io_cqe *cqe, + struct io_big_cqe *big_cqe) +{ + struct io_overflow_cqe *ocqe; + + ocqe = io_alloc_ocqe(ctx, cqe, big_cqe, GFP_ATOMIC); + return io_cqring_add_overflow(ctx, ocqe); +} + bool io_post_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags) { bool filled; @@ -820,11 +841,9 @@ bool io_post_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags io_cq_lock(ctx); filled = io_fill_cqe_aux(ctx, user_data, res, cflags); if (unlikely(!filled)) { - struct io_overflow_cqe *ocqe; struct io_cqe cqe = io_init_cqe(user_data, res, cflags); - ocqe = io_alloc_ocqe(ctx, &cqe, NULL, GFP_ATOMIC); - filled = io_cqring_add_overflow(ctx, ocqe); + filled = io_cqe_overflow_locked(ctx, &cqe, NULL); } io_cq_unlock_post(ctx); return filled; @@ -840,13 +859,9 @@ void io_add_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags) lockdep_assert(ctx->lockless_cq); if (!io_fill_cqe_aux(ctx, user_data, res, cflags)) { - struct io_overflow_cqe *ocqe; struct io_cqe cqe = io_init_cqe(user_data, res, cflags); - ocqe = io_alloc_ocqe(ctx, &cqe, NULL, GFP_KERNEL); - spin_lock(&ctx->completion_lock); - io_cqring_add_overflow(ctx, ocqe); - spin_unlock(&ctx->completion_lock); + io_cqe_overflow(ctx, &cqe, NULL); } ctx->submit_state.cq_flush = true; } @@ -1450,17 +1465,10 @@ void __io_submit_flush_completions(struct io_ring_ctx *ctx) */ if (!(req->flags & (REQ_F_CQE_SKIP | REQ_F_REISSUE)) && unlikely(!io_fill_cqe_req(ctx, req))) { - gfp_t gfp = ctx->lockless_cq ? GFP_KERNEL : GFP_ATOMIC; - struct io_overflow_cqe *ocqe; - - ocqe = io_alloc_ocqe(ctx, &req->cqe, &req->big_cqe, gfp); - if (ctx->lockless_cq) { - spin_lock(&ctx->completion_lock); - io_cqring_add_overflow(ctx, ocqe); - spin_unlock(&ctx->completion_lock); - } else { - io_cqring_add_overflow(ctx, ocqe); - } + if (ctx->lockless_cq) + io_cqe_overflow(ctx, &req->cqe, &req->big_cqe); + else + io_cqe_overflow_locked(ctx, &req->cqe, &req->big_cqe); } } __io_cq_unlock_post(ctx); -- 2.25.1