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From:   Stefan Roesch <shr@fb.com>
To:     <io-uring@vger.kernel.org>, <linux-nvme@lists.infradead.org>,
        <kernel-team@fb.com>
CC:     <shr@fb.com>, <joshi.k@samsung.com>
Subject: [PATCH v3 06/12] io_uring: modify io_get_cqe for CQE32
Date:   Mon, 25 Apr 2022 11:25:24 -0700
Message-ID: <20220425182530.2442911-7-shr@fb.com>
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Modify accesses to the CQE array to take large CQE's into account. The
index needs to be shifted by one for large CQE's.

Signed-off-by: Stefan Roesch <shr@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/io_uring.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index f300130fd9f0..726238dc65dc 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1909,8 +1909,12 @@ static noinline struct io_uring_cqe *__io_get_cqe(=
struct io_ring_ctx *ctx)
 {
 	struct io_rings *rings =3D ctx->rings;
 	unsigned int off =3D ctx->cached_cq_tail & (ctx->cq_entries - 1);
+	unsigned int shift =3D 0;
 	unsigned int free, queued, len;
=20
+	if (ctx->flags & IORING_SETUP_CQE32)
+		shift =3D 1;
+
 	/* userspace may cheat modifying the tail, be safe and do min */
 	queued =3D min(__io_cqring_events(ctx), ctx->cq_entries);
 	free =3D ctx->cq_entries - queued;
@@ -1922,15 +1926,26 @@ static noinline struct io_uring_cqe *__io_get_cqe=
(struct io_ring_ctx *ctx)
 	ctx->cached_cq_tail++;
 	ctx->cqe_cached =3D &rings->cqes[off];
 	ctx->cqe_sentinel =3D ctx->cqe_cached + len;
-	return ctx->cqe_cached++;
+	ctx->cqe_cached++;
+	return &rings->cqes[off << shift];
 }
=20
 static inline struct io_uring_cqe *io_get_cqe(struct io_ring_ctx *ctx)
 {
 	if (likely(ctx->cqe_cached < ctx->cqe_sentinel)) {
+		struct io_uring_cqe *cqe =3D ctx->cqe_cached;
+
+		if (ctx->flags & IORING_SETUP_CQE32) {
+			unsigned int off =3D ctx->cqe_cached - ctx->rings->cqes;
+
+			cqe +=3D off;
+		}
+
 		ctx->cached_cq_tail++;
-		return ctx->cqe_cached++;
+		ctx->cqe_cached++;
+		return cqe;
 	}
+
 	return __io_get_cqe(ctx);
 }
=20
--=20
2.30.2