• Daniel Mentz's avatar
    ARC: Call trace_hardirqs_on() before enabling irqs · e44f5b53
    Daniel Mentz authored
    commit 18b43e89 upstream.
    
    trace_hardirqs_on_caller() in lockdep.c expects to be called before, not
    after interrupts are actually enabled.
    
    The following comment in kernel/locking/lockdep.c substantiates this
    claim:
    
    "
    /*
     * We're enabling irqs and according to our state above irqs weren't
     * already enabled, yet we find the hardware thinks they are in fact
     * enabled.. someone messed up their IRQ state tracing.
     */
    "
    
    An example can be found in include/linux/irqflags.h:
    
    	do { trace_hardirqs_on(); raw_local_irq_enable(); } while (0)
    
    Without this change, we hit the following DEBUG_LOCKS_WARN_ON.
    
    [    7.760000] ------------[ cut here ]------------
    [    7.760000] WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:2711 resume_user_mode_begin+0x48/0xf0
    [    7.770000] DEBUG_LOCKS_WARN_ON(!irqs_disabled())
    [    7.780000] Modules linked in:
    [    7.780000] CPU: 0 PID: 1 Comm: init Not tainted 4.7.0-00003-gc668bb9-dirty #366
    [    7.790000]
    [    7.790000] Stack Trace:
    [    7.790000]   arc_unwind_core.constprop.1+0xa4/0x118
    [    7.800000]   warn_slowpath_fmt+0x72/0x158
    [    7.800000]   resume_user_mode_begin+0x48/0xf0
    [    7.810000] ---[ end trace 6f6a7a8fae20d2f0 ]---
    Signed-off-by: default avatarDaniel Mentz <danielmentz@google.com>
    Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    e44f5b53
irqflags-compact.h 4.27 KB