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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Robert Lippert <rlippert@google.com>,
        Corey Minyard <cminyard@mvista.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.9 098/177] ipmi/watchdog: fix wdog hang on panic waiting for ipmi response
Date:   Fri, 23 Mar 2018 10:53:46 +0100
Message-Id: <20180323094209.608400602@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Robert Lippert <roblip@gmail.com>


[ Upstream commit 2c1175c2e8e5487233cabde358a19577562ac83e ]

Commit c49c097610fe ("ipmi: Don't call receive handler in the
panic context") means that the panic_recv_free is not called during a
panic and the atomic count does not drop to 0.

Fix this by only expecting one decrement of the atomic variable
which comes from panic_smi_free.

Signed-off-by: Robert Lippert <rlippert@google.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/char/ipmi/ipmi_watchdog.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/char/ipmi/ipmi_watchdog.c
+++ b/drivers/char/ipmi/ipmi_watchdog.c
@@ -515,7 +515,7 @@ static void panic_halt_ipmi_heartbeat(vo
 	msg.cmd = IPMI_WDOG_RESET_TIMER;
 	msg.data = NULL;
 	msg.data_len = 0;
-	atomic_add(2, &panic_done_count);
+	atomic_add(1, &panic_done_count);
 	rv = ipmi_request_supply_msgs(watchdog_user,
 				      (struct ipmi_addr *) &addr,
 				      0,
@@ -525,7 +525,7 @@ static void panic_halt_ipmi_heartbeat(vo
 				      &panic_halt_heartbeat_recv_msg,
 				      1);
 	if (rv)
-		atomic_sub(2, &panic_done_count);
+		atomic_sub(1, &panic_done_count);
 }
 
 static struct ipmi_smi_msg panic_halt_smi_msg = {
@@ -549,12 +549,12 @@ static void panic_halt_ipmi_set_timeout(
 	/* Wait for the messages to be free. */
 	while (atomic_read(&panic_done_count) != 0)
 		ipmi_poll_interface(watchdog_user);
-	atomic_add(2, &panic_done_count);
+	atomic_add(1, &panic_done_count);
 	rv = i_ipmi_set_timeout(&panic_halt_smi_msg,
 				&panic_halt_recv_msg,
 				&send_heartbeat_now);
 	if (rv) {
-		atomic_sub(2, &panic_done_count);
+		atomic_sub(1, &panic_done_count);
 		printk(KERN_WARNING PFX
 		       "Unable to extend the watchdog timeout.");
 	} else {