Le 16/01/2022 à 22:42, Andrew Lunn a écrit :

On Sun, Jan 16, 2022 at 07:46:20PM +0100, Christophe JAILLET wrote:

quoted

ice_misc_intr() is an irq handler. It should not sleep.

Use GFP_ATOMIC instead of GFP_KERNEL when allocating some memory.

Fixes: 348048e724a0 ("ice: Implement iidc operations")
Signed-off-by: Christophe JAILLET <redacted>
---
I've never played a lot with irq handler. My understanding is that they
should never sleep.

Hi Christophe

Threaded interrupt handlers are allowed to sleep. However, this
handler is not being used in such a way. So your are probably correct
about GFP_KERNEL vs GFP_ATOMIC.

quoted

---
  drivers/net/ethernet/intel/ice/ice_main.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
index 30814435f779..65de01f3a504 100644
--- a/drivers/net/ethernet/intel/ice/ice_main.c
+++ b/drivers/net/ethernet/intel/ice/ice_main.c

@@ -3018,7 +3018,7 @@ static irqreturn_t ice_misc_intr(int __always_unused irq, void *data)
  		struct iidc_event *event;
  
  		ena_mask &= ~ICE_AUX_CRIT_ERR;
-		event = kzalloc(sizeof(*event), GFP_KERNEL);
+		event = kzalloc(sizeof(*event), GFP_ATOMIC);
  		if (event) {
  			set_bit(IIDC_EVENT_CRIT_ERR, event->type);
  			/* report the entire OICR value to AUX driver */

What happens next is interesting...


                         event->reg = oicr;
                         ice_send_event_to_aux(pf, event);

where:

void ice_send_event_to_aux(struct ice_pf *pf, struct iidc_event *event)
{
         struct iidc_auxiliary_drv *iadrv;

         if (!pf->adev)
                 return;

         device_lock(&pf->adev->dev);
         iadrv = ice_get_auxiliary_drv(pf);
         if (iadrv && iadrv->event_handler)
                 iadrv->event_handler(pf, event);
         device_unlock(&pf->adev->dev);
}

device_lock() takes a mutex, not something you should be doing in
atomic context.

So it looks to me, this handler really should be running in thread
context...

	Andrew

Ok, thanks for the explanation.

ice_misc_intr() is registered with devm_request_irq(), so it is a 
handler that can't sleep.

I guess that more consideration should be taken into account than only:
   s/devm_request_irq(handler)/devm_request_threaded_irq(NULL, handler)/

So I'll leave this one to people with the expected know-how.

If my s/GFP_KERNEL/GFP_ATOMIC/ makes enough sense as-is, that's fine for 
me, but it looks that another solution is needed to fix the 2nd issue.


CJ