linux-kernel - Re: [PATCH v2 1/3] mei: vsc: Call wake

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Date: Mon, 4 Mar 2024 10:42:18 +0000
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: "Wu, Wentong" <wentong.wu@...el.com>
Cc: Hans de Goede <hdegoede@...hat.com>,
	"Winkler, Tomas" <tomas.winkler@...el.com>,
	Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] mei: vsc: Call wake_up() in the threaded IRQ
 handler

Hi Wentong,

On Wed, Feb 28, 2024 at 08:19:04AM +0000, Wu, Wentong wrote:
> > -----Original Message-----
> > From: Sakari Ailus <sakari.ailus@...ux.intel.com>
> >
> > The hard IRQ handler vsc_tp_irq() is called with a raw spinlock taken.
> > wake_up() acquires a spinlock, a sleeping lock on PREEMPT_RT. This leads to
> > sleeping in atomic context.
> > 
> > Move the wake_up() call to the threaded IRQ handler vsc_tp_thread_isr()
> > where it can be safely called.
> > 
> > Fixes: 566f5ca97680 ("mei: Add transport driver for IVSC device")
> > Signed-off-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
> 
> Tested-and-Reviewed-by: Wentong Wu <wentong.wu@...el.com>

Thanks!

I dug a little bit deeper and it seems the lockdep warning this patch fixes
is something we can safely ignore, see
<URL:https://wiki.archlinux.org/title/Realtime_kernel_patchset#How_does_the_realtime_patch_work>.
My apologies for the noise.

The two other patches in the set are still unaffected by this.

-- 
Regards,

Sakari Ailus