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io_uring: split alloc and add of overflow 

Add a new helper, io_alloc_ocqe(), that simply allocates and fills an
overflow entry. Then it can get done outside of the locking section,
and hence use more appropriate gfp_t allocation flags rather than always
default to GFP_ATOMIC.

Inspired by a previous series from Pavel:

https://lore.kernel.org/io-uring/cover.1747209332.git.asml.silence@gmail.com/

Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
pull/1250/head
Jens Axboe 2025-05-16 09:39:14 -06:00
parent 5288b9e28f
commit 10f466abc4
1 changed files with 45 additions and 29 deletions
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74
io_uring/io_uring.c
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@ -697,20 +697,11 @@ static __cold void io_uring_drop_tctx_refs(struct task_struct *task)
}
}
static bool io_cqring_event_overflow(struct io_ring_ctx *ctx, u64 user_data,
s32 res, u32 cflags, u64 extra1, u64 extra2)
static bool io_cqring_add_overflow(struct io_ring_ctx *ctx,
struct io_overflow_cqe *ocqe)
{
struct io_overflow_cqe *ocqe;
size_t ocq_size = sizeof(struct io_overflow_cqe);
bool is_cqe32 = (ctx->flags & IORING_SETUP_CQE32);
lockdep_assert_held(&ctx->completion_lock);
if (is_cqe32)
ocq_size += sizeof(struct io_uring_cqe);
ocqe = kmalloc(ocq_size, GFP_ATOMIC | __GFP_ACCOUNT);
trace_io_uring_cqe_overflow(ctx, user_data, res, cflags, ocqe);
if (!ocqe) {
struct io_rings *r = ctx->rings;
@ -728,17 +719,35 @@ static bool io_cqring_event_overflow(struct io_ring_ctx *ctx, u64 user_data,
atomic_or(IORING_SQ_CQ_OVERFLOW, &ctx->rings->sq_flags);
}
ocqe->cqe.user_data = user_data;
ocqe->cqe.res = res;
ocqe->cqe.flags = cflags;
if (is_cqe32) {
ocqe->cqe.big_cqe[0] = extra1;
ocqe->cqe.big_cqe[1] = extra2;
}
list_add_tail(&ocqe->list, &ctx->cq_overflow_list);
return true;
}
static struct io_overflow_cqe *io_alloc_ocqe(struct io_ring_ctx *ctx,
u64 user_data, s32 res, u32 cflags,
u64 extra1, u64 extra2, gfp_t gfp)
{
struct io_overflow_cqe *ocqe;
size_t ocq_size = sizeof(struct io_overflow_cqe);
bool is_cqe32 = (ctx->flags & IORING_SETUP_CQE32);
if (is_cqe32)
ocq_size += sizeof(struct io_uring_cqe);
ocqe = kmalloc(ocq_size, gfp | __GFP_ACCOUNT);
trace_io_uring_cqe_overflow(ctx, user_data, res, cflags, ocqe);
if (ocqe) {
ocqe->cqe.user_data = user_data;
ocqe->cqe.res = res;
ocqe->cqe.flags = cflags;
if (is_cqe32) {
ocqe->cqe.big_cqe[0] = extra1;
ocqe->cqe.big_cqe[1] = extra2;
}
}
return ocqe;
}
/*
* writes to the cq entry need to come after reading head; the
* control dependency is enough as we're using WRITE_ONCE to
@ -803,8 +812,12 @@ 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 (!filled)
filled = io_cqring_event_overflow(ctx, user_data, res, cflags, 0, 0);
if (unlikely(!filled)) {
struct io_overflow_cqe *ocqe;
ocqe = io_alloc_ocqe(ctx, user_data, res, cflags, 0, 0, GFP_ATOMIC);
filled = io_cqring_add_overflow(ctx, ocqe);
}
io_cq_unlock_post(ctx);
return filled;
}
@ -819,8 +832,11 @@ 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;
ocqe = io_alloc_ocqe(ctx, user_data, res, cflags, 0, 0, GFP_KERNEL);
spin_lock(&ctx->completion_lock);
io_cqring_event_overflow(ctx, user_data, res, cflags, 0, 0);
io_cqring_add_overflow(ctx, ocqe);
spin_unlock(&ctx->completion_lock);
}
ctx->submit_state.cq_flush = true;
@ -1425,18 +1441,18 @@ 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.user_data, req->cqe.res,
req->cqe.flags, req->big_cqe.extra1,
req->big_cqe.extra2, gfp);
if (ctx->lockless_cq) {
spin_lock(&ctx->completion_lock);
io_cqring_event_overflow(req->ctx, req->cqe.user_data,
req->cqe.res, req->cqe.flags,
req->big_cqe.extra1,
req->big_cqe.extra2);
io_cqring_add_overflow(ctx, ocqe);
spin_unlock(&ctx->completion_lock);
} else {
io_cqring_event_overflow(req->ctx, req->cqe.user_data,
req->cqe.res, req->cqe.flags,
req->big_cqe.extra1,
req->big_cqe.extra2);
io_cqring_add_overflow(ctx, ocqe);
}
memset(&req->big_cqe, 0, sizeof(req->big_cqe));