• David S. Miller's avatar
    sparc64: Fix lockdep warnings on reboot on Ultra-5 · bdcf81b6
    David S. Miller authored
    Inconsistently, the raw_* IRQ routines do not interact with and update
    the irqflags tracing and lockdep state, whereas the raw_* spinlock
    interfaces do.
    
    This causes problems in p1275_cmd_direct() because we disable hardirqs
    by hand using raw_local_irq_restore() and then do a raw_spin_lock()
    which triggers a lockdep trace because the CPU's hw IRQ state doesn't
    match IRQ tracing's internal software copy of that state.
    
    The CPU's irqs are disabled, yet current->hardirqs_enabled is true.
    
    ====================
    reboot: Restarting system
    ------------[ cut here ]------------
    WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:3536 check_flags+0x7c/0x240()
    DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled)
    Modules linked in: openpromfs
    CPU: 0 PID: 1 Comm: systemd-shutdow Tainted: G        W      3.17.0-dirty #145
    Call Trace:
     [000000000045919c] warn_slowpath_common+0x5c/0xa0
     [0000000000459210] warn_slowpath_fmt+0x30/0x40
     [000000000048f41c] check_flags+0x7c/0x240
     [0000000000493280] lock_acquire+0x20/0x1c0
     [0000000000832b70] _raw_spin_lock+0x30/0x60
     [000000000068f2fc] p1275_cmd_direct+0x1c/0x60
     [000000000068ed28] prom_reboot+0x28/0x40
     [000000000043610c] machine_restart+0x4c/0x80
     [000000000047d2d4] kernel_restart+0x54/0x80
     [000000000047d618] SyS_reboot+0x138/0x200
     [00000000004060b4] linux_sparc_syscall32+0x34/0x60
    ---[ end trace 5c439fe81c05a100 ]---
    possible reason: unannotated irqs-off.
    irq event stamp: 2010267
    hardirqs last  enabled at (2010267): [<000000000049a358>] vprintk_emit+0x4b8/0x580
    hardirqs last disabled at (2010266): [<0000000000499f08>] vprintk_emit+0x68/0x580
    softirqs last  enabled at (2010046): [<000000000045d278>] __do_softirq+0x378/0x4a0
    softirqs last disabled at (2010039): [<000000000042bf08>] do_softirq_own_stack+0x28/0x40
    Resetting ...
    ====================
    
    Use local_* variables of the hw IRQ interfaces so that IRQ tracing sees
    all of our changes.
    Reported-by: default avatarMeelis Roos <mroos@linux.ee>
    Tested-by: default avatarMeelis Roos <mroos@linux.ee>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    bdcf81b6
p1275.c 1.21 KB