[SRU][bionic][PATCH 4/5] powerpc/powernv: Fix opal_event_shutdown() called with interrupts disabled

[Kamal Mostafa]

From: Nicholas Piggin <npiggin at gmail.com>

BugLink: http://bugs.launchpad.net/bugs/1790636

A kernel crash in process context that calls emergency_restart from
panic will end up calling opal_event_shutdown with interrupts disabled
but not in interrupt. This causes a sleeping function to be called
which gives the following warning with sysrq+c:

    Rebooting in 10 seconds..
    BUG: sleeping function called from invalid context at kernel/locking/mutex.c:238
    in_atomic(): 0, irqs_disabled(): 1, pid: 7669, name: bash
    CPU: 20 PID: 7669 Comm: bash Tainted: G      D W         4.17.0-rc5+ #3
    Call Trace:
    dump_stack+0xb0/0xf4 (unreliable)
    ___might_sleep+0x174/0x1a0
    mutex_lock+0x38/0xb0
    __free_irq+0x68/0x460
    free_irq+0x70/0xc0
    opal_event_shutdown+0xb4/0xf0
    opal_shutdown+0x24/0xa0
    pnv_shutdown+0x28/0x40
    machine_shutdown+0x44/0x60
    machine_restart+0x28/0x80
    emergency_restart+0x30/0x50
    panic+0x2a0/0x328
    oops_end+0x1ec/0x1f0
    bad_page_fault+0xe8/0x154
    handle_page_fault+0x34/0x38
    --- interrupt: 300 at sysrq_handle_crash+0x44/0x60
    LR = __handle_sysrq+0xfc/0x260
    flag_spec.62335+0x12b844/0x1e8db4 (unreliable)
    __handle_sysrq+0xfc/0x260
    write_sysrq_trigger+0xa8/0xb0
    proc_reg_write+0xac/0x110
    __vfs_write+0x6c/0x240
    vfs_write+0xd0/0x240
    ksys_write+0x6c/0x110

Fixes: 9f0fd0499d30 ("powerpc/powernv: Add a virtual irqchip for opal events")
Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
(cherry picked from commit 8bf84f005346fd0ecfa595c2d497b19a6e291b4e)
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 arch/powerpc/platforms/powernv/opal-irqchip.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/powernv/opal-irqchip.c b/arch/powerpc/platforms/powernv/opal-irqchip.c
index 9d1b8c0..05ffe05 100644
--- a/arch/powerpc/platforms/powernv/opal-irqchip.c
+++ b/arch/powerpc/platforms/powernv/opal-irqchip.c
@@ -177,7 +177,7 @@ void opal_event_shutdown(void)
 		if (!opal_irqs[i])
 			continue;
 
-		if (in_interrupt())
+		if (in_interrupt() || irqs_disabled())
 			disable_irq_nosync(opal_irqs[i]);
 		else
 			free_irq(opal_irqs[i], NULL);
-- 
2.7.4