linux-kernel - Re: [PATCH 1/1] Improve kernfs_notify() poll notification latency

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Message-ID: <20181120165842.GB28793@kroah.com>
Date:   Tue, 20 Nov 2018 17:58:42 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Tejun Heo <tj@...nel.org>
Cc:     Radu Rendec <radu.rendec@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] Improve kernfs_notify() poll notification latency

On Tue, Nov 20, 2018 at 08:14:19AM -0800, Tejun Heo wrote:
> On Thu, Nov 15, 2018 at 09:09:54PM -0500, Radu Rendec wrote:
> > kernfs_notify() does two notifications: poll and fsnotify. Originally,
> > both notifications were done from scheduled work context and all that
> > kernfs_notify() did was schedule the work.
> > 
> > This patch simply moves the poll notification from the scheduled work
> > handler to kernfs_notify(). The fsnotify notification still needs to be
> > done from scheduled work context because it can sleep (it needs to lock
> > a mutex).
> > 
> > If the poll notification is time critical (the notified thread needs to
> > wake as quickly as possible), it's better to do it from kernfs_notify()
> > directly. One example is calling sysfs_notify_dirent() from a hardware
> > interrupt handler to wake up a thread and handle the interrupt in user
> > space.
> > 
> > Signed-off-by: Radu Rendec <radu.rendec@...il.com>
> 
> Acked-by: Tejun Heo <tj@...nel.org>
> 
> Greg, can you please route this one?

Sure, I'll queue it up soon...

greg k-h