From: Greg KH <greg@kroah.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: USB list <linux-usb@vger.kernel.org>
Subject: Re: [PATCH] USB: core: Remove usbfs_mutex
Date: Wed, 26 Jun 2019 10:30:58 +0800 [thread overview]
Message-ID: <20190626023058.GA18819@kroah.com> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1906251600270.1493-100000@iolanthe.rowland.org>
On Tue, Jun 25, 2019 at 04:03:58PM -0400, Alan Stern wrote:
> Commit 4a2a8a2cce86 ("usbfs: private mutex for open, release, and
> remove") is now obsolete. The commit was created back when we had
> to handle both usbfs device nodes and the old usbdevfs filesystem
> (/proc/bus/usb/), but usbdevfs no longer exists.
>
> This means there's no longer any need to hold a mutex during two
> separate removal operations (and thus during an entire notifier chain
> call). Furthermore, the one remaining remove/release pair doesn't
> race with open thanks to the synchronization provided by the device
> model core in bus_find_device(). Remove and release don't race with
> each other because they both run with the device lock held.
>
> The upshot is that usbfs_mutex isn't needed any more. This patch
> removes it entirely.
>
> Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
>
Ah, nice, I forgot all about this mutex, thanks for removing it!
greg k-h
prev parent reply other threads:[~2019-06-26 2:35 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-25 20:03 [PATCH] USB: core: Remove usbfs_mutex Alan Stern
2019-06-26 2:30 ` Greg KH [this message]
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