RE: [PATCH V5 6/9] firmware: imx: scu-irq: fix RCU complains after M4 partition reset

[Peng Fan]

> Subject: Re: [PATCH V5 6/9] firmware: imx: scu-irq: fix RCU complains after
> M4 partition reset
> 
> On Mon, Jul 31, 2023 at 05:04:46PM +0800, Peng Fan (OSS) wrote:
> > From: Robin Gong <yibin.gong@xxxxxxx>
> >
> > Use blocking_notifier_chain instead of atomic_notifier_chain,
> > otherwise below RCU complains would come out since
> > unregister/register_virtio_device
> 
> s/complains/complaint, and in subject too.
> 
> > () will issue mbox message (mbox_send_message() is blocking) again
> > after
> 
> The () should be on the same line as register_virtio_device.
> 
> > received M4 partition reset. Actually, no need atomic for notifier
> > which
> 
> there is no need of atomic for ...?

I'll rephase the commit log in v6. There is no need to use atomic
notifier for scu irq notification.

Thanks,
Peng.

> 
> Shawn
> 
> > is so tough for user since this notifier is called in worker instead
> > of interrupt handler directly.
> >
> > [  389.706645] i2c-rpmsg virtio0.rpmsg-i2c-channel.-1.2: i2c rpmsg
> > driver is removed [  389.767362] Wait for remote ready timeout, use
> first_notify.
> > [  389.774084] ------------[ cut here ]------------ [  389.778729]
> > WARNING: CPU: 0 PID: 397 at kernel/rcu/tree_plugin.h:293
> > rcu_note_context_switch+0x34/0x338
> > [  389.788131] Modules linked in:
> > [  389.791195] CPU: 0 PID: 397 Comm: kworker/0:13 Not tainted
> > 5.4.0-rc5-02977-g08f78722f07b #26 [  389.799633] Hardware name:
> > Freescale i.MX8DXL Phantom MEK (DT) [  389.805481] Workqueue: events
> > imx_scu_irq_work_handler
> >
> > Signed-off-by: Robin Gong <yibin.gong@xxxxxxx>
> > Reviewed-by: Dong Aisheng <aisheng.dong@xxxxxxx>
> > Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
> > ---
> >  drivers/firmware/imx/imx-scu-irq.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/firmware/imx/imx-scu-irq.c
> > b/drivers/firmware/imx/imx-scu-irq.c
> > index d9dcc20945c6..4408f150b3d5 100644
> > --- a/drivers/firmware/imx/imx-scu-irq.c
> > +++ b/drivers/firmware/imx/imx-scu-irq.c
> > @@ -42,25 +42,25 @@ struct imx_sc_msg_irq_enable {
> >
> >  static struct imx_sc_ipc *imx_sc_irq_ipc_handle;  static struct
> > work_struct imx_sc_irq_work; -static
> > ATOMIC_NOTIFIER_HEAD(imx_scu_irq_notifier_chain);
> > +static BLOCKING_NOTIFIER_HEAD(imx_scu_irq_notifier_chain);
> >
> >  int imx_scu_irq_register_notifier(struct notifier_block *nb)  {
> > -	return atomic_notifier_chain_register(
> > +	return blocking_notifier_chain_register(
> >  		&imx_scu_irq_notifier_chain, nb);
> >  }
> >  EXPORT_SYMBOL(imx_scu_irq_register_notifier);
> >
> >  int imx_scu_irq_unregister_notifier(struct notifier_block *nb)  {
> > -	return atomic_notifier_chain_unregister(
> > +	return blocking_notifier_chain_unregister(
> >  		&imx_scu_irq_notifier_chain, nb);
> >  }
> >  EXPORT_SYMBOL(imx_scu_irq_unregister_notifier);
> >
> >  static int imx_scu_irq_notifier_call_chain(unsigned long status, u8
> > *group)  {
> > -	return atomic_notifier_call_chain(&imx_scu_irq_notifier_chain,
> > +	return blocking_notifier_call_chain(&imx_scu_irq_notifier_chain,
> >  		status, (void *)group);
> >  }
> >
> > --
> > 2.37.1
> >