ipmi: Allow an SMI sender to return an error

Getting ready for handling when a BMC is non-responsive or broken, allow
the sender operation to fail in an SMI.  If it was a user-generated
message it will return the error.

The powernv code was already doing this internally, but the way it was
written could result in deep stack descent if there were a lot of
messages queued.  Have its send return an error in this case.

Signed-off-by: Corey Minyard <corey@minyard.net>

drivers/char/ipmi/ipmi_ipmb.c

@@ -404,8 +404,7 @@ static void ipmi_ipmb_shutdown(void *send_info)
 	ipmi_ipmb_stop_thread(iidev);
 }
 
-static void ipmi_ipmb_sender(void *send_info,
+static int ipmi_ipmb_sender(void *send_info, struct ipmi_smi_msg *msg)
-			     struct ipmi_smi_msg *msg)
 {
 	struct ipmi_ipmb_dev *iidev = send_info;
 	unsigned long flags;
@@ -417,6 +416,7 @@ static void ipmi_ipmb_sender(void *send_info,
 	spin_unlock_irqrestore(&iidev->lock, flags);
 
 	up(&iidev->wake_thread);
+	return IPMI_CC_NO_ERROR;
 }
 
 static void ipmi_ipmb_request_events(void *send_info)

drivers/char/ipmi/ipmi_msghandler.c

@@ -4803,6 +4803,7 @@ static void smi_work(struct work_struct *t)
 	int run_to_completion = READ_ONCE(intf->run_to_completion);
 	struct ipmi_smi_msg *newmsg = NULL;
 	struct ipmi_recv_msg *msg, *msg2;
+	int cc;
 
 	/*
 	 * Start the next message if available.
@@ -4811,7 +4812,7 @@ static void smi_work(struct work_struct *t)
 	 * because the lower layer is allowed to hold locks while calling
 	 * message delivery.
 	 */
-
+restart:
 	if (!run_to_completion)
 		spin_lock_irqsave(&intf->xmit_msgs_lock, flags);
 	if (intf->curr_msg == NULL && !intf->in_shutdown) {
@@ -4832,8 +4833,17 @@ static void smi_work(struct work_struct *t)
 	if (!run_to_completion)
 		spin_unlock_irqrestore(&intf->xmit_msgs_lock, flags);
 
-	if (newmsg)
+	if (newmsg) {
-		intf->handlers->sender(intf->send_info, newmsg);
+		cc = intf->handlers->sender(intf->send_info, newmsg);
+		if (cc) {
+			if (newmsg->user_data)
+				deliver_err_response(intf,
+						     newmsg->user_data, cc);
+			else
+				ipmi_free_smi_msg(newmsg);
+			goto restart;
+		}
+	}
 
 	handle_new_recv_msgs(intf);
 

drivers/char/ipmi/ipmi_powernv.c

@@ -51,7 +51,7 @@ static void send_error_reply(struct ipmi_smi_powernv *smi,
 	ipmi_smi_msg_received(smi->intf, msg);
 }
 
-static void ipmi_powernv_send(void *send_info, struct ipmi_smi_msg *msg)
+static int ipmi_powernv_send(void *send_info, struct ipmi_smi_msg *msg)
 {
 	struct ipmi_smi_powernv *smi = send_info;
 	struct opal_ipmi_msg *opal_msg;
@@ -93,18 +93,19 @@ static void ipmi_powernv_send(void *send_info, struct ipmi_smi_msg *msg)
 			smi->interface_id, opal_msg, size);
 	rc = opal_ipmi_send(smi->interface_id, opal_msg, size);
 	pr_devel("%s:  -> %d\n", __func__, rc);
-
+	if (rc) {
-	if (!rc) {
+		comp = IPMI_ERR_UNSPECIFIED;
-		smi->cur_msg = msg;
+		goto err_unlock;
-		spin_unlock_irqrestore(&smi->msg_lock, flags);
-		return;
 	}
 
-	comp = IPMI_ERR_UNSPECIFIED;
+	smi->cur_msg = msg;
+	spin_unlock_irqrestore(&smi->msg_lock, flags);
+	return IPMI_CC_NO_ERROR;
+
 err_unlock:
 	spin_unlock_irqrestore(&smi->msg_lock, flags);
 err:
-	send_error_reply(smi, msg, comp);
+	return comp;
 }
 
 static int ipmi_powernv_recv(struct ipmi_smi_powernv *smi)

drivers/char/ipmi/ipmi_si_intf.c

@@ -809,8 +809,6 @@ static enum si_sm_result smi_event_handler(struct smi_info *smi_info,
 	 * this if there is not yet an upper layer to handle anything.
 	 */
 	if (si_sm_result == SI_SM_ATTN || smi_info->got_attn) {
-		unsigned char msg[2];
-
 		if (smi_info->si_state != SI_NORMAL) {
 			/*
 			 * We got an ATTN, but we are doing something else.
@@ -907,8 +905,7 @@ static void flush_messages(void *send_info)
 	}
 }
 
-static void sender(void                *send_info,
+static int sender(void *send_info, struct ipmi_smi_msg *msg)
-		   struct ipmi_smi_msg *msg)
 {
 	struct smi_info   *smi_info = send_info;
 	unsigned long     flags;
@@ -921,7 +918,7 @@ static void sender(void                *send_info,
 		 * layer will call flush_messages to clear it out.
 		 */
 		smi_info->waiting_msg = msg;
-		return;
+		return IPMI_CC_NO_ERROR;
 	}
 
 	spin_lock_irqsave(&smi_info->si_lock, flags);
@@ -936,6 +933,7 @@ static void sender(void                *send_info,
 	smi_info->waiting_msg = msg;
 	check_start_timer_thread(smi_info);
 	spin_unlock_irqrestore(&smi_info->si_lock, flags);
+	return IPMI_CC_NO_ERROR;
 }
 
 static void set_run_to_completion(void *send_info, bool i_run_to_completion)

drivers/char/ipmi/ipmi_ssif.c

@@ -1068,8 +1068,7 @@ static void start_next_msg(struct ssif_info *ssif_info, unsigned long *flags)
 	}
 }
 
-static void sender(void                *send_info,
+static int sender(void *send_info, struct ipmi_smi_msg *msg)
-		   struct ipmi_smi_msg *msg)
 {
 	struct ssif_info *ssif_info = send_info;
 	unsigned long oflags, *flags;
@@ -1089,6 +1088,7 @@ static void sender(void                *send_info,
 			msg->data[0], msg->data[1],
 			(long long)t.tv_sec, (long)t.tv_nsec / NSEC_PER_USEC);
 	}
+	return IPMI_CC_NO_ERROR;
 }
 
 static int get_smi_info(void *send_info, struct ipmi_smi_info *data)

include/linux/ipmi_smi.h

@@ -168,9 +168,11 @@ struct ipmi_smi_handlers {
 	 * are held when this is run.  Message are delivered one at
 	 * a time by the message handler, a new message will not be
 	 * delivered until the previous message is returned.
+	 *
+	 * This can return an error if the SMI is not in a state where it
+	 * can send a message.
 	 */
-	void (*sender)(void                *send_info,
+	int (*sender)(void *send_info, struct ipmi_smi_msg *msg);
-		       struct ipmi_smi_msg *msg);
 
 	/*
 	 * Called by the upper layer to request that we try to get