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From: Al Viro <viro@zeniv.linux.org.uk>
To: Imran Khan <imran.f.khan@oracle.com>
Cc: tj@kernel.org, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org
Subject: Re: [RESEND PATCH v7 1/8] kernfs: Introduce interface to access global kernfs_open_file_mutex.
Date: Wed, 6 Apr 2022 14:54:44 +0000	[thread overview]
Message-ID: <Yk2ptLIKdpvgL3QY@zeniv-ca.linux.org.uk> (raw)
In-Reply-To: <0dfe1056-3dc5-4d31-698e-e2c075ffd6ee@oracle.com>

On Wed, Apr 06, 2022 at 02:54:19PM +1000, Imran Khan wrote:

> > BTW, speaking of kernfs_notify() - can calls of that come from NMI handlers?
> > If not, I'd consider using llist for kernfs_notify_list...
> 
> I see it gets invoked from 3 places only: cgroup_file_notify,
> sysfs_notify and sysfs_notify_dirent. So kernfs_notify should not be
> getting invoked in NMI context. I will make the llist transition in next
> version.

Er...  Are you sure neither of those is ever called from something that is
called from .... from NMI?

It might never happen, but there's a plenty of callchains leading to that
thing and no obvious obstacles for some of those to come from NMI context;
I don't see it documented anywhere either.

Tejun, could you comment on that one?

  reply	other threads:[~2022-04-06 16:54 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-17  7:26 [RESEND PATCH v7 0/8] kernfs: Introduce interface to access global kernfs_open_file_mutex Imran Khan
2022-03-17  7:26 ` [RESEND PATCH v7 1/8] " Imran Khan
2022-03-17 21:34   ` Al Viro
2022-04-05  5:36     ` Imran Khan
2022-04-05 14:24       ` Al Viro
2022-04-06  4:54         ` Imran Khan
2022-04-06 14:54           ` Al Viro [this message]
2022-04-06 15:18             ` Tejun Heo
2022-04-14  0:01           ` Imran Khan
2022-03-18 17:10   ` Eric W. Biederman
2022-03-21  0:10     ` Imran Khan
2022-03-17  7:26 ` [RESEND PATCH v7 2/8] kernfs: Replace global kernfs_open_file_mutex with hashed mutexes Imran Khan
2022-03-17  7:26 ` [RESEND PATCH v7 3/8] kernfs: Introduce interface to access kernfs_open_node_lock Imran Khan
2022-03-17  7:26 ` [RESEND PATCH v7 4/8] kernfs: Replace global kernfs_open_node_lock with hashed spinlocks Imran Khan
2022-03-17  7:26 ` [RESEND PATCH v7 5/8] kernfs: Use a per-fs rwsem to protect per-fs list of kernfs_super_info Imran Khan
2022-03-17  7:26 ` [RESEND PATCH v7 6/8] kernfs: Introduce interface to access per-fs rwsem Imran Khan
2022-03-17  7:26 ` [RESEND PATCH v7 7/8] kernfs: Replace per-fs rwsem with hashed rwsems Imran Khan
2022-03-18  0:07   ` Al Viro
2022-03-21  1:57     ` Imran Khan
2022-03-21  7:29       ` Al Viro
2022-03-21 16:46         ` Tejun Heo
2022-03-21 17:55           ` Al Viro
2022-03-21 19:20             ` Tejun Heo
2022-03-22  2:40               ` Al Viro
2022-03-22 17:08                 ` Tejun Heo
2022-03-22 20:26                   ` Al Viro
2022-03-22 21:20                     ` Tejun Heo
2022-03-28  0:15                 ` Imran Khan
2022-03-28 17:30                   ` Tejun Heo
2022-03-30  2:23                 ` Imran Khan
2022-03-17  7:26 ` [RESEND PATCH v7 8/8] kernfs: Add a document to describe hashed locks used in kernfs Imran Khan

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