linux-kernel - [PATCH 4.2.y-ckt 169/305] ipmi: move timer init to before irq is setup

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Message-Id: <1452902519-2754-170-git-send-email-kamal@canonical.com>
Date:	Fri, 15 Jan 2016 15:59:43 -0800
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Jan Stancek <jstancek@...hat.com>,
	Tony Camuso <tcamuso@...hat.com>,
	Corey Minyard <cminyard@...sta.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 169/305] ipmi: move timer init to before irq is setup

4.2.8-ckt2 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Jan Stancek <jstancek@...hat.com>

commit 27f972d3e00b50639deb4cc1392afaeb08d3cecc upstream.

We encountered a panic on boot in ipmi_si on a dell per320 due to an
uninitialized timer as follows.

static int smi_start_processing(void       *send_info,
                                ipmi_smi_t intf)
{
        /* Try to claim any interrupts. */
        if (new_smi->irq_setup)
                new_smi->irq_setup(new_smi);

 --> IRQ arrives here and irq handler tries to modify uninitialized timer

    which triggers BUG_ON(!timer->function) in __mod_timer().

 Call Trace:
   <IRQ>
   [<ffffffffa0532617>] start_new_msg+0x47/0x80 [ipmi_si]
   [<ffffffffa053269e>] start_check_enables+0x4e/0x60 [ipmi_si]
   [<ffffffffa0532bd8>] smi_event_handler+0x1e8/0x640 [ipmi_si]
   [<ffffffff810f5584>] ? __rcu_process_callbacks+0x54/0x350
   [<ffffffffa053327c>] si_irq_handler+0x3c/0x60 [ipmi_si]
   [<ffffffff810efaf0>] handle_IRQ_event+0x60/0x170
   [<ffffffff810f245e>] handle_edge_irq+0xde/0x180
   [<ffffffff8100fc59>] handle_irq+0x49/0xa0
   [<ffffffff8154643c>] do_IRQ+0x6c/0xf0
   [<ffffffff8100ba53>] ret_from_intr+0x0/0x11

        /* Set up the timer that drives the interface. */
        setup_timer(&new_smi->si_timer, smi_timeout, (long)new_smi);

The following patch fixes the problem.

To: Openipmi-developer@...ts.sourceforge.net
To: Corey Minyard <minyard@....org>
CC: linux-kernel@...r.kernel.org

Signed-off-by: Jan Stancek <jstancek@...hat.com>
Signed-off-by: Tony Camuso <tcamuso@...hat.com>
Signed-off-by: Corey Minyard <cminyard@...sta.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/char/ipmi/ipmi_si_intf.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
index 88a7bdd..0522270 100644
--- a/drivers/char/ipmi/ipmi_si_intf.c
+++ b/drivers/char/ipmi/ipmi_si_intf.c
@@ -1218,14 +1218,14 @@ static int smi_start_processing(void       *send_info,
 
 	new_smi->intf = intf;
 
-	/* Try to claim any interrupts. */
-	if (new_smi->irq_setup)
-		new_smi->irq_setup(new_smi);
-
 	/* Set up the timer that drives the interface. */
 	setup_timer(&new_smi->si_timer, smi_timeout, (long)new_smi);
 	smi_mod_timer(new_smi, jiffies + SI_TIMEOUT_JIFFIES);
 
+	/* Try to claim any interrupts. */
+	if (new_smi->irq_setup)
+		new_smi->irq_setup(new_smi);
+
 	/*
 	 * Check if the user forcefully enabled the daemon.
 	 */
-- 
1.9.1