6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jens Axboe <axboe@xxxxxxxxx>
commit 6b69c4ab4f685327d9e10caf0d84217ba23a8c4b upstream.
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@xxxxxxxxxxxxxxx # v6.4+
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
io_uring/kbuf.c | 15 +++++++++++----
io_uring/kbuf.h | 2 ++
2 files changed, 13 insertions(+), 4 deletions(-)
--- a/io_uring/kbuf.c
+++ b/io_uring/kbuf.c
@@ -59,6 +59,7 @@ static int io_buffer_add_list(struct io_
* 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));
}
@@ -272,6 +273,14 @@ static int __io_remove_buffers(struct io
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;
@@ -279,8 +288,7 @@ void io_destroy_buffers(struct io_ring_c
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);
}
while (!list_empty(&ctx->io_buffers_pages)) {
@@ -676,9 +684,8 @@ int io_unregister_pbuf_ring(struct io_ri
if (!bl->is_mapped)
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;
}
--- 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_mapped;
/* ring mapped provided buffers, but mmap'ed by application */
