From: Pavel Begunkov <asml.silence@gmail.com>
Date: Wed, 5 Feb 2025 11:36:45 +0000 (+0000)
Subject: io_uring/kbuf: simplify __io_put_kbuf
X-Git-Tag: for-6.15/io_uring-20250322~96
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=dc39fb1093ea33019f192c93b77b863282e10162;p=linux-block.git

io_uring/kbuf: simplify __io_put_kbuf

As a preparation step remove an optimisation from __io_put_kbuf() trying
to use the locked cache. With that __io_put_kbuf_list() is only used
with ->io_buffers_comp, and we remove the explicit list argument.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1b7f1394ec4afc7f96b35a61f5992e27c49fd067.1738724373.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c
index 2e1561c9220f..3a43af9f7061 100644
--- a/io_uring/kbuf.c
+++ b/io_uring/kbuf.c
@@ -70,29 +70,9 @@ bool io_kbuf_recycle_legacy(struct io_kiocb *req, unsigned issue_flags)
 
 void __io_put_kbuf(struct io_kiocb *req, int len, unsigned issue_flags)
 {
-	/*
-	 * We can add this buffer back to two lists:
-	 *
-	 * 1) The io_buffers_cache list. This one is protected by the
-	 *    ctx->uring_lock. If we already hold this lock, add back to this
-	 *    list as we can grab it from issue as well.
-	 * 2) The io_buffers_comp list. This one is protected by the
-	 *    ctx->completion_lock.
-	 *
-	 * We migrate buffers from the comp_list to the issue cache list
-	 * when we need one.
-	 */
-	if (issue_flags & IO_URING_F_UNLOCKED) {
-		struct io_ring_ctx *ctx = req->ctx;
-
-		spin_lock(&ctx->completion_lock);
-		__io_put_kbuf_list(req, len, &ctx->io_buffers_comp);
-		spin_unlock(&ctx->completion_lock);
-	} else {
-		lockdep_assert_held(&req->ctx->uring_lock);
-
-		__io_put_kbuf_list(req, len, &req->ctx->io_buffers_cache);
-	}
+	spin_lock(&req->ctx->completion_lock);
+	__io_put_kbuf_list(req, len);
+	spin_unlock(&req->ctx->completion_lock);
 }
 
 static void __user *io_provided_buffer_select(struct io_kiocb *req, size_t *len,
diff --git a/io_uring/kbuf.h b/io_uring/kbuf.h
index 310f94a0727a..1f2877064829 100644
--- a/io_uring/kbuf.h
+++ b/io_uring/kbuf.h
@@ -160,14 +160,13 @@ static inline bool __io_put_kbuf_ring(struct io_kiocb *req, int len, int nr)
 	return ret;
 }
 
-static inline void __io_put_kbuf_list(struct io_kiocb *req, int len,
-				      struct list_head *list)
+static inline void __io_put_kbuf_list(struct io_kiocb *req, int len)
 {
 	if (req->flags & REQ_F_BUFFER_RING) {
 		__io_put_kbuf_ring(req, len, 1);
 	} else {
 		req->buf_index = req->kbuf->bgid;
-		list_add(&req->kbuf->list, list);
+		list_add(&req->kbuf->list, &req->ctx->io_buffers_comp);
 		req->flags &= ~REQ_F_BUFFER_SELECTED;
 	}
 }
@@ -179,7 +178,7 @@ static inline void io_kbuf_drop(struct io_kiocb *req)
 
 	spin_lock(&req->ctx->completion_lock);
 	/* len == 0 is fine here, non-ring will always drop all of it */
-	__io_put_kbuf_list(req, 0, &req->ctx->io_buffers_comp);
+	__io_put_kbuf_list(req, 0);
 	spin_unlock(&req->ctx->completion_lock);
 }