From: Tejun Heo <tj@kernel.org>
To: Imran Khan <imran.f.khan@oracle.com>
Cc: viro@zeniv.linux.org.uk, gregkh@linuxfoundation.org,
ebiederm@xmission.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v8 01/10] kernfs: Remove reference counting for kernfs_open_node.
Date: Fri, 22 Apr 2022 06:03:17 -1000 [thread overview]
Message-ID: <YmLRxWUnF/zflEO2@slm.duckdns.org> (raw)
In-Reply-To: <20220410023719.1752460-2-imran.f.khan@oracle.com>
On Sun, Apr 10, 2022 at 12:37:10PM +1000, Imran Khan wrote:
> @@ -768,15 +765,15 @@ void kernfs_drain_open_files(struct kernfs_node *kn)
> if (!(kn->flags & (KERNFS_HAS_MMAP | KERNFS_HAS_RELEASE)))
> return;
>
> - spin_lock_irq(&kernfs_open_node_lock);
> on = kn->attr.open;
> - if (on)
> - atomic_inc(&on->refcnt);
> - spin_unlock_irq(&kernfs_open_node_lock);
> if (!on)
> return;
>
> mutex_lock(&kernfs_open_file_mutex);
> + if (!kn->attr.open) {
> + mutex_unlock(&kernfs_open_file_mutex);
> + return;
> + }
What if @on got freed and new one got allocated between the lockless check
and the locked check? Is there a reason to keep the lockless check at all?
> list_for_each_entry(of, &on->files, list) {
> struct inode *inode = file_inode(of->file);
Thanks.
--
tejun
next prev parent reply other threads:[~2022-04-22 16:03 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-10 2:37 [PATCH v8 00/10] kernfs: Remove reference counting for kernfs_open_node Imran Khan
2022-04-10 2:37 ` [PATCH v8 01/10] " Imran Khan
2022-04-22 16:03 ` Tejun Heo [this message]
2022-04-26 1:43 ` Imran Khan
2022-04-26 18:29 ` Tejun Heo
2022-04-26 20:13 ` Al Viro
2022-04-26 20:16 ` Tejun Heo
2022-04-10 2:37 ` [PATCH v8 02/10] kernfs: make ->attr.open RCU protected Imran Khan
2022-04-22 16:19 ` Tejun Heo
2022-04-26 1:54 ` Imran Khan
2022-04-26 18:37 ` Tejun Heo
2022-04-10 2:37 ` [PATCH v8 03/10] kernfs: Change kernfs_notify_list to llist Imran Khan
2022-04-22 16:41 ` Tejun Heo
2022-04-10 2:37 ` [PATCH v8 04/10] kernfs: Introduce interface to access global kernfs_open_file_mutex Imran Khan
2022-04-10 2:37 ` [PATCH v8 05/10] kernfs: Replace global kernfs_open_file_mutex with hashed mutexes Imran Khan
2022-04-22 17:00 ` Tejun Heo
2022-04-10 2:37 ` [PATCH v8 06/10] kernfs: Use a per-fs rwsem to protect per-fs list of kernfs_super_info Imran Khan
2022-04-10 2:37 ` [PATCH v8 07/10] kernfs: Change kernfs_rename_lock into a read-write lock Imran Khan
2022-04-10 2:37 ` [PATCH v8 08/10] kernfs: Introduce interface to access per-fs rwsem Imran Khan
2022-04-10 2:37 ` [PATCH v8 09/10] kernfs: Replace per-fs rwsem with hashed rwsems Imran Khan
2022-04-10 2:37 ` [PATCH v8 10/10] kernfs: Add a document to describe hashed locks used in kernfs Imran Khan
2022-04-22 17:03 ` [PATCH v8 00/10] kernfs: Remove reference counting for kernfs_open_node Tejun Heo
2022-04-23 8:49 ` Imran Khan
2022-04-25 17:21 ` Tejun Heo
2022-04-28 17:28 ` Imran Khan
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