From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Wed, 16 Mar 2022 16:38:42 +0000 (+0100)
Subject: 5.10-stable patches
X-Git-Tag: v5.4.186~14
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=955e312c78fda68be0c429ff0117882e1bd7ca8a;p=thirdparty%2Fkernel%2Fstable-queue.git

5.10-stable patches

added patches:
	io_uring-return-back-safer-resurrect.patch
---

diff --git a/queue-5.10/io_uring-return-back-safer-resurrect.patch b/queue-5.10/io_uring-return-back-safer-resurrect.patch
new file mode 100644
index 00000000000..6c97d9a57f7
--- /dev/null
+++ b/queue-5.10/io_uring-return-back-safer-resurrect.patch
@@ -0,0 +1,74 @@
+From f70865db5ff35f5ed0c7e9ef63e7cca3d4947f04 Mon Sep 17 00:00:00 2001
+From: Pavel Begunkov <asml.silence@gmail.com>
+Date: Sun, 11 Apr 2021 01:46:40 +0100
+Subject: io_uring: return back safer resurrect
+
+From: Pavel Begunkov <asml.silence@gmail.com>
+
+commit f70865db5ff35f5ed0c7e9ef63e7cca3d4947f04 upstream.
+
+Revert of revert of "io_uring: wait potential ->release() on resurrect",
+which adds a helper for resurrect not racing completion reinit, as was
+removed because of a strange bug with no clear root or link to the
+patch.
+
+Was improved, instead of rcu_synchronize(), just wait_for_completion()
+because we're at 0 refs and it will happen very shortly. Specifically
+use non-interruptible version to ignore all pending signals that may
+have ended prior interruptible wait.
+
+This reverts commit cb5e1b81304e089ee3ca948db4d29f71902eb575.
+
+Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
+Link: https://lore.kernel.org/r/7a080c20f686d026efade810b116b72f88abaff9.1618101759.git.asml.silence@gmail.com
+Signed-off-by: Jens Axboe <axboe@kernel.dk>
+Cc: Lee Jones <lee.jones@linaro.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ fs/io_uring.c |   18 ++++++++++++++----
+ 1 file changed, 14 insertions(+), 4 deletions(-)
+
+--- a/fs/io_uring.c
++++ b/fs/io_uring.c
+@@ -1009,6 +1009,18 @@ static inline bool __io_match_files(stru
+ 		req->work.identity->files == files;
+ }
+ 
++static void io_refs_resurrect(struct percpu_ref *ref, struct completion *compl)
++{
++	bool got = percpu_ref_tryget(ref);
++
++	/* already at zero, wait for ->release() */
++	if (!got)
++		wait_for_completion(compl);
++	percpu_ref_resurrect(ref);
++	if (got)
++		percpu_ref_put(ref);
++}
++
+ static bool io_match_task(struct io_kiocb *head,
+ 			  struct task_struct *task,
+ 			  struct files_struct *files)
+@@ -9757,12 +9769,11 @@ static int __io_uring_register(struct io
+ 			if (ret < 0)
+ 				break;
+ 		} while (1);
+-
+ 		mutex_lock(&ctx->uring_lock);
+ 
+ 		if (ret) {
+-			percpu_ref_resurrect(&ctx->refs);
+-			goto out_quiesce;
++			io_refs_resurrect(&ctx->refs, &ctx->ref_comp);
++			return ret;
+ 		}
+ 	}
+ 
+@@ -9855,7 +9866,6 @@ out:
+ 	if (io_register_op_must_quiesce(opcode)) {
+ 		/* bring the ctx back to life */
+ 		percpu_ref_reinit(&ctx->refs);
+-out_quiesce:
+ 		reinit_completion(&ctx->ref_comp);
+ 	}
+ 	return ret;
diff --git a/queue-5.10/series b/queue-5.10/series
index 9a8f5b80696..850626b6281 100644
--- a/queue-5.10/series
+++ b/queue-5.10/series
@@ -20,3 +20,4 @@ tcp-make-tcp_read_sock-more-robust.patch
 sfc-extend-the-locking-on-mcdi-seqno.patch
 bnx2-fix-an-error-message.patch
 kselftest-vm-fix-tests-build-with-old-libc.patch
+io_uring-return-back-safer-resurrect.patch