Patch "io_uring: kill fasync" has been added to the 5.14-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    io_uring: kill fasync

to the 5.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     io_uring-kill-fasync.patch
and it can be found in the queue-5.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit afc14c8d7826b1c45a27eb386bb732c582811bbe
Author: Pavel Begunkov <asml.silence@xxxxxxxxx>
Date:   Fri Oct 1 10:39:33 2021 +0100

    io_uring: kill fasync
    
    [ Upstream commit 3f008385d46d3cea4a097d2615cd485f2184ba26 ]
    
    We have never supported fasync properly, it would only fire when there
    is something polling io_uring making it useless. The original support came
    in through the initial io_uring merge for 5.1. Since it's broken and
    nobody has reported it, get rid of the fasync bits.
    
    Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
    Link: https://lore.kernel.org/r/2f7ca3d344d406d34fa6713824198915c41cea86.1633080236.git.asml.silence@xxxxxxxxx
    Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 675216f7022d..2f79586c1a7c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -419,7 +419,6 @@ struct io_ring_ctx {
 		struct wait_queue_head	cq_wait;
 		unsigned		cq_extra;
 		atomic_t		cq_timeouts;
-		struct fasync_struct	*cq_fasync;
 		unsigned		cq_last_tm_flush;
 	} ____cacheline_aligned_in_smp;
 
@@ -1448,10 +1447,8 @@ static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
 		wake_up(&ctx->sq_data->wait);
 	if (io_should_trigger_evfd(ctx))
 		eventfd_signal(ctx->cq_ev_fd, 1);
-	if (waitqueue_active(&ctx->poll_wait)) {
+	if (waitqueue_active(&ctx->poll_wait))
 		wake_up_interruptible(&ctx->poll_wait);
-		kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN);
-	}
 }
 
 static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx)
@@ -1465,10 +1462,8 @@ static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx)
 	}
 	if (io_should_trigger_evfd(ctx))
 		eventfd_signal(ctx->cq_ev_fd, 1);
-	if (waitqueue_active(&ctx->poll_wait)) {
+	if (waitqueue_active(&ctx->poll_wait))
 		wake_up_interruptible(&ctx->poll_wait);
-		kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN);
-	}
 }
 
 /* Returns true if there are no backlogged entries after the flush */
@@ -8779,13 +8774,6 @@ static __poll_t io_uring_poll(struct file *file, poll_table *wait)
 	return mask;
 }
 
-static int io_uring_fasync(int fd, struct file *file, int on)
-{
-	struct io_ring_ctx *ctx = file->private_data;
-
-	return fasync_helper(fd, file, on, &ctx->cq_fasync);
-}
-
 static int io_unregister_personality(struct io_ring_ctx *ctx, unsigned id)
 {
 	const struct cred *creds;
@@ -9571,7 +9559,6 @@ static const struct file_operations io_uring_fops = {
 	.mmap_capabilities = io_uring_nommu_mmap_capabilities,
 #endif
 	.poll		= io_uring_poll,
-	.fasync		= io_uring_fasync,
 #ifdef CONFIG_PROC_FS
 	.show_fdinfo	= io_uring_show_fdinfo,
 #endif