queue-6.6/io_uring-kbuf-get-rid-of-bl-is_ready.patch

   1 From 3b80cff5a4d117c53d38ce805823084eaeffbde6 Mon Sep 17 00:00:00 2001
   2 From: Jens Axboe <axboe@kernel.dk>
   3 Date: Thu, 14 Mar 2024 10:46:40 -0600
   4 Subject: io_uring/kbuf: get rid of bl->is_ready
   5
   6 From: Jens Axboe <axboe@kernel.dk>
   7
   8 commit 3b80cff5a4d117c53d38ce805823084eaeffbde6 upstream.
   9
  10 Now that xarray is being exclusively used for the buffer_list lookup,
  11 this check is no longer needed. Get rid of it and the is_ready member.
  12
  13 Cc: stable@vger.kernel.org # v6.4+
  14 Signed-off-by: Jens Axboe <axboe@kernel.dk>
  15 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  16 ---
  17  io_uring/kbuf.c |    8 --------
  18  io_uring/kbuf.h |    2 --
  19  2 files changed, 10 deletions(-)
  20
  21 --- a/io_uring/kbuf.c
  22 +++ b/io_uring/kbuf.c
  23 @@ -59,7 +59,6 @@ static int io_buffer_add_list(struct io_
  24          * always under the ->uring_lock, but the RCU lookup from mmap does.
  25          */
  26         bl->bgid = bgid;
  27 -       smp_store_release(&bl->is_ready, 1);
  28         return xa_err(xa_store(&ctx->io_bl_xa, bgid, bl, GFP_KERNEL));
  29  }
  30
  31 @@ -691,13 +690,6 @@ void *io_pbuf_get_address(struct io_ring
  32
  33         if (!bl || !bl->is_mmap)
  34                 return NULL;
  35 -       /*
  36 -        * Ensure the list is fully setup. Only strictly needed for RCU lookup
  37 -        * via mmap, and in that case only for the array indexed groups. For
  38 -        * the xarray lookups, it's either visible and ready, or not at all.
  39 -        */
  40 -       if (!smp_load_acquire(&bl->is_ready))
  41 -               return NULL;
  42
  43         return bl->buf_ring;
  44  }
  45 --- a/io_uring/kbuf.h
  46 +++ b/io_uring/kbuf.h
  47 @@ -29,8 +29,6 @@ struct io_buffer_list {
  48         __u8 is_mapped;
  49         /* ring mapped provided buffers, but mmap'ed by application */
  50         __u8 is_mmap;
  51 -       /* bl is visible from an RCU point of view for lookup */
  52 -       __u8 is_ready;
  53  };
  54
  55  struct io_buffer {