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    Subject[PATCH AUTOSEL 4.9 18/21] ARM: 8839/1: kprobe: make patch_lock a raw_spinlock_t
    Date
    From: Yang Shi <yang.shi@linaro.org>

    [ Upstream commit 143c2a89e0e5fda6c6fd08d7bc1126438c19ae90 ]

    When running kprobe on -rt kernel, the below bug is caught:

    |BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:931
    |in_atomic(): 1, irqs_disabled(): 128, pid: 14, name: migration/0
    |Preemption disabled at:[<802f2b98>] cpu_stopper_thread+0xc0/0x140
    |CPU: 0 PID: 14 Comm: migration/0 Tainted: G O 4.8.3-rt2 #1
    |Hardware name: Freescale LS1021A
    |[<8025a43c>] (___might_sleep)
    |[<80b5b324>] (rt_spin_lock)
    |[<80b5c31c>] (__patch_text_real)
    |[<80b5c3ac>] (patch_text_stop_machine)
    |[<802f2920>] (multi_cpu_stop)

    Since patch_text_stop_machine() is called in stop_machine() which
    disables IRQ, sleepable lock should be not used in this atomic context,
    so replace patch_lock to raw lock.

    Signed-off-by: Yang Shi <yang.shi@linaro.org>
    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    Reviewed-by: Arnd Bergmann <arnd@arndb.de>
    Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    arch/arm/kernel/patch.c | 6 +++---
    1 file changed, 3 insertions(+), 3 deletions(-)

    diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c
    index 69bda1a5707e..1f665acaa6a9 100644
    --- a/arch/arm/kernel/patch.c
    +++ b/arch/arm/kernel/patch.c
    @@ -15,7 +15,7 @@ struct patch {
    unsigned int insn;
    };

    -static DEFINE_SPINLOCK(patch_lock);
    +static DEFINE_RAW_SPINLOCK(patch_lock);

    static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
    __acquires(&patch_lock)
    @@ -32,7 +32,7 @@ static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
    return addr;

    if (flags)
    - spin_lock_irqsave(&patch_lock, *flags);
    + raw_spin_lock_irqsave(&patch_lock, *flags);
    else
    __acquire(&patch_lock);

    @@ -47,7 +47,7 @@ static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
    clear_fixmap(fixmap);

    if (flags)
    - spin_unlock_irqrestore(&patch_lock, *flags);
    + raw_spin_unlock_irqrestore(&patch_lock, *flags);
    else
    __release(&patch_lock);
    }
    --
    2.19.1
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