Hi Neelesh,

This fix looks reasonable to me, although Jeremy would be the best person to 
comment if he has time. I wonder why we bother polling at all given that our 
event interface should call opal_ipmi_recv() whenever a message is ready?

Also the firmware fix you refer to and this fix are independent of each other 
so there's no ordering issues there.

Reviewed-By: Alistair Popple <alistair@popple.id.au>

On Tue, 28 Jul 2015 13:20:07 Neelesh Gupta wrote:

On 07/17/2015 02:12 PM, Neelesh Gupta wrote:

Hi Corey,

On 07/16/2015 08:31 PM, Corey Minyard wrote:

Ok, this looks fine.  A couple of question...

Do I need to send this upstream right now?  How well has this been 

tested?

I would want either Jeremy or Alistair to review this patch before you 
send this
upstream. There is also firmware piece 
http://patchwork.ozlabs.org/patch/496645/
awaiting review.

In the testing front, I manually made the opal_ipmi_recv() function to 
fail for testing
the error path and see if the driver recovers from it and subsequent 
ipmi commands
work all good.

Hi Jeremy/Alistair,

Could you please review it and the corresponding skiboot patch...

Thanks,
Neelesh.

Do you want this backported to 4.0 stable?

Yes, I want this to be be backported to 4.0 stable.

Thanks,
Neelesh.

-corey

On 07/16/2015 06:16 AM, Neelesh Gupta wrote:

If the OPAL call to receive the ipmi message fails, then we free up the
smi message and return. But, the driver still holds the reference to
old smi message in the 'cur_msg' which can potentially be accessed later
and freed again leading to kernel oops. To fix it up,

The kernel driver should reset the 'cur_msg' and send reply to the user
in addition to freeing the message.

Signed-off-by: Neelesh Gupta<neelegup@linux.vnet.ibm.com>
---
  drivers/char/ipmi/ipmi_powernv.c |   13 ++++++++++---
  1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/char/ipmi/ipmi_powernv.c 

b/drivers/char/ipmi/ipmi_powernv.c

index 9b409c0..637486d 100644
--- a/drivers/char/ipmi/ipmi_powernv.c
+++ b/drivers/char/ipmi/ipmi_powernv.c
@@ -143,9 +143,16 @@ static int ipmi_powernv_recv(struct 

ipmi_smi_powernv *smi)

  	pr_devel("%s:   -> %d (size %lld)\n", __func__,
  			rc, rc == 0 ? size : 0);
  	if (rc) {
-		spin_unlock_irqrestore(&smi->msg_lock, flags);
-		ipmi_free_smi_msg(msg);
-		return 0;
+		/* If came via the poll, and response was not yet ready */
+		if (rc == OPAL_EMPTY) {
+			spin_unlock_irqrestore(&smi->msg_lock, flags);
+			return 0;
+		} else {
+			smi->cur_msg = NULL;
+			spin_unlock_irqrestore(&smi->msg_lock, flags);
+			send_error_reply(smi, msg, IPMI_ERR_UNSPECIFIED);
+			return 0;
+		}
  	}

  	if (size < sizeof(*opal_msg)) {

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