No functional changes in this patch, just in preparation for being able to keep the buffer list alive outside of the ctx->uring_lock.

Cc: stable@vger.kernel.org # v6.4+ Signed-off-by: Jens Axboe axboe@kernel.dk --- io_uring/kbuf.c | 15 +++++++++++---- io_uring/kbuf.h | 2 ++ 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c index 011280d873e7..2edc6854f6f3 100644 --- a/io_uring/kbuf.c +++ b/io_uring/kbuf.c @@ -61,6 +61,7 @@ static int io_buffer_add_list(struct io_ring_ctx *ctx, * always under the ->uring_lock, but the RCU lookup from mmap does. */ bl->bgid = bgid; + atomic_set(&bl->refs, 1); return xa_err(xa_store(&ctx->io_bl_xa, bgid, bl, GFP_KERNEL)); }

@@ -265,6 +266,14 @@ static int __io_remove_buffers(struct io_ring_ctx *ctx, return i; }

+static void io_put_bl(struct io_ring_ctx *ctx, struct io_buffer_list *bl) +{ + if (atomic_dec_and_test(&bl->refs)) { + __io_remove_buffers(ctx, bl, -1U); + kfree_rcu(bl, rcu); + } +} + void io_destroy_buffers(struct io_ring_ctx *ctx) { struct io_buffer_list *bl; @@ -274,8 +283,7 @@ void io_destroy_buffers(struct io_ring_ctx *ctx)

xa_for_each(&ctx->io_bl_xa, index, bl) { xa_erase(&ctx->io_bl_xa, bl->bgid); - __io_remove_buffers(ctx, bl, -1U); - kfree_rcu(bl, rcu); + io_put_bl(ctx, bl); }

/* @@ -680,9 +688,8 @@ int io_unregister_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg) if (!bl->is_buf_ring) return -EINVAL;

- __io_remove_buffers(ctx, bl, -1U); xa_erase(&ctx->io_bl_xa, bl->bgid); - kfree_rcu(bl, rcu); + io_put_bl(ctx, bl); return 0; }

diff --git a/io_uring/kbuf.h b/io_uring/kbuf.h index fdbb10449513..8b868a1744e2 100644 --- a/io_uring/kbuf.h +++ b/io_uring/kbuf.h @@ -25,6 +25,8 @@ struct io_buffer_list { __u16 head; __u16 mask;

+ atomic_t refs; + /* ring mapped provided buffers */ __u8 is_buf_ring; /* ring mapped provided buffers, but mmap'ed by application */