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    Subject[PATCH 3.14 081/100] sparc64: Fix lockdep warnings on reboot on Ultra-5
    Date
    3.14-stable review patch.  If anyone has any objections, please let me know.

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

    From: "David S. Miller" <davem@davemloft.net>

    [ Upstream commit bdcf81b658ebc4c2640c3c2c55c8b31c601b6996 ]

    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: Meelis Roos <mroos@linux.ee>
    Tested-by: Meelis Roos <mroos@linux.ee>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    arch/sparc/prom/p1275.c | 7 ++++---
    1 file changed, 4 insertions(+), 3 deletions(-)

    --- a/arch/sparc/prom/p1275.c
    +++ b/arch/sparc/prom/p1275.c
    @@ -9,6 +9,7 @@
    #include <linux/smp.h>
    #include <linux/string.h>
    #include <linux/spinlock.h>
    +#include <linux/irqflags.h>

    #include <asm/openprom.h>
    #include <asm/oplib.h>
    @@ -36,8 +37,8 @@ void p1275_cmd_direct(unsigned long *arg
    {
    unsigned long flags;

    - raw_local_save_flags(flags);
    - raw_local_irq_restore((unsigned long)PIL_NMI);
    + local_save_flags(flags);
    + local_irq_restore((unsigned long)PIL_NMI);
    raw_spin_lock(&prom_entry_lock);

    prom_world(1);
    @@ -45,7 +46,7 @@ void p1275_cmd_direct(unsigned long *arg
    prom_world(0);

    raw_spin_unlock(&prom_entry_lock);
    - raw_local_irq_restore(flags);
    + local_irq_restore(flags);
    }

    void prom_cif_init(void *cif_handler, void *cif_stack)



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