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    Subject[PATCH RT 6/7] kernel: sched: Fix preempt_disable_ip recodring for preempt_disable()
    3.4.110-rt140-rc1 stable review patch.
    If anyone has any objections, please let me know.

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

    From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

    preempt_disable() invokes preempt_count_add() which saves the caller in
    current->preempt_disable_ip. It uses CALLER_ADDR1 which does not look for its
    caller but for the parent of the caller. Which means we get the correct caller
    for something like spin_lock() unless the architectures inlines those
    invocations. It is always wrong for preempt_disable() or local_bh_disable().

    This patch makes the function get_parent_ip() which tries CALLER_ADDR0,1,2 if
    the former is a locking function. This seems to record the preempt_disable()
    caller properly for preempt_disable() itself as well as for get_cpu_var() or
    local_bh_disable().

    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
    ---
    include/linux/ftrace.h | 12 ++++++++++++
    include/linux/sched.h | 2 --
    kernel/sched/core.c | 14 ++------------
    kernel/softirq.c | 2 +-
    4 files changed, 15 insertions(+), 15 deletions(-)

    diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
    index bfbcd439e2c6..93bce698fb86 100644
    --- a/include/linux/ftrace.h
    +++ b/include/linux/ftrace.h
    @@ -476,6 +476,18 @@ static inline void __ftrace_enabled_restore(int enabled)
    # endif
    #endif /* ifndef HAVE_ARCH_CALLER_ADDR */

    +static inline unsigned long get_lock_parent_ip(void)
    +{
    + unsigned long addr = CALLER_ADDR0;
    +
    + if (!in_lock_functions(addr))
    + return addr;
    + addr = CALLER_ADDR1;
    + if (!in_lock_functions(addr))
    + return addr;
    + return CALLER_ADDR2;
    +}
    +
    #ifdef CONFIG_IRQSOFF_TRACER
    extern void time_hardirqs_on(unsigned long a0, unsigned long a1);
    extern void time_hardirqs_off(unsigned long a0, unsigned long a1);
    diff --git a/include/linux/sched.h b/include/linux/sched.h
    index daf469059630..029575fb9bc8 100644
    --- a/include/linux/sched.h
    +++ b/include/linux/sched.h
    @@ -148,8 +148,6 @@ extern unsigned long this_cpu_load(void);
    extern void calc_global_load(unsigned long ticks);
    extern void update_cpu_load_nohz(void);

    -extern unsigned long get_parent_ip(unsigned long addr);
    -
    struct seq_file;
    struct cfs_rq;
    struct task_group;
    diff --git a/kernel/sched/core.c b/kernel/sched/core.c
    index 7d9a53d80d22..ec9bfbef9873 100644
    --- a/kernel/sched/core.c
    +++ b/kernel/sched/core.c
    @@ -3241,16 +3241,6 @@ void scheduler_tick(void)
    #endif
    }

    -notrace unsigned long get_parent_ip(unsigned long addr)
    -{
    - if (in_lock_functions(addr)) {
    - addr = CALLER_ADDR2;
    - if (in_lock_functions(addr))
    - addr = CALLER_ADDR3;
    - }
    - return addr;
    -}
    -
    #if defined(CONFIG_PREEMPT) && (defined(CONFIG_DEBUG_PREEMPT) || \
    defined(CONFIG_PREEMPT_TRACER))

    @@ -3272,7 +3262,7 @@ void __kprobes add_preempt_count(int val)
    PREEMPT_MASK - 10);
    #endif
    if (preempt_count() == val) {
    - unsigned long ip = get_parent_ip(CALLER_ADDR1);
    + unsigned long ip = get_lock_parent_ip();
    #ifdef CONFIG_DEBUG_PREEMPT
    current->preempt_disable_ip = ip;
    #endif
    @@ -3298,7 +3288,7 @@ void __kprobes sub_preempt_count(int val)
    #endif

    if (preempt_count() == val)
    - trace_preempt_on(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
    + trace_preempt_on(CALLER_ADDR0, get_lock_parent_ip());
    preempt_count() -= val;
    }
    EXPORT_SYMBOL(sub_preempt_count);
    diff --git a/kernel/softirq.c b/kernel/softirq.c
    index d2c870a826da..2cdd5102331b 100644
    --- a/kernel/softirq.c
    +++ b/kernel/softirq.c
    @@ -207,7 +207,7 @@ static void __local_bh_disable(unsigned long ip, unsigned int cnt)
    raw_local_irq_restore(flags);

    if (preempt_count() == cnt)
    - trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
    + trace_preempt_off(CALLER_ADDR0, get_lock_parent_ip());
    }
    #else /* !CONFIG_TRACE_IRQFLAGS */
    static inline void __local_bh_disable(unsigned long ip, unsigned int cnt)
    --
    2.7.0

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