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    Subject[PATCH AUTOSEL 5.19 042/105] refscale: Convert test_lock spinlock to raw_spinlock
    Date
    From: Zqiang <qiang1.zhang@intel.com>

    [ Upstream commit 7bf336fb8dac718febb7bf4fe79e1be0c5e4a631 ]

    In kernels built with CONFIG_PREEMPT_RT=y, spinlocks are replaced by
    rt_mutex, which can sleep. This means that acquiring a non-raw spinlock
    in a critical section where preemption is disabled can trigger the
    following BUG:

    BUG: scheduling while atomic: ref_scale_reade/76/0x00000002
    Preemption disabled at:
    ref_lock_section+0x16/0x80
    Call Trace:
    <TASK>
    dump_stack_lvl+0x5b/0x82
    dump_stack+0x10/0x12
    __schedule_bug.cold+0x9c/0xad
    __schedule+0x839/0xc00
    schedule_rtlock+0x22/0x40
    rtlock_slowlock_locked+0x460/0x1350
    rt_spin_lock+0x61/0xe0
    ref_lock_section+0x29/0x80
    rcu_scale_one_reader+0x52/0x60
    ref_scale_reader+0x28d/0x490
    kthread+0x128/0x150
    ret_from_fork+0x22/0x30
    </TASK>

    This commit therefore converts spinlock to raw_spinlock.

    Signed-off-by: Zqiang <qiang1.zhang@intel.com>
    Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    kernel/rcu/refscale.c | 18 +++++++++---------
    1 file changed, 9 insertions(+), 9 deletions(-)

    diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
    index 909644abee67..435c884c02b5 100644
    --- a/kernel/rcu/refscale.c
    +++ b/kernel/rcu/refscale.c
    @@ -385,7 +385,7 @@ static struct ref_scale_ops rwsem_ops = {
    };

    // Definitions for global spinlock
    -static DEFINE_SPINLOCK(test_lock);
    +static DEFINE_RAW_SPINLOCK(test_lock);

    static void ref_lock_section(const int nloops)
    {
    @@ -393,8 +393,8 @@ static void ref_lock_section(const int nloops)

    preempt_disable();
    for (i = nloops; i >= 0; i--) {
    - spin_lock(&test_lock);
    - spin_unlock(&test_lock);
    + raw_spin_lock(&test_lock);
    + raw_spin_unlock(&test_lock);
    }
    preempt_enable();
    }
    @@ -405,9 +405,9 @@ static void ref_lock_delay_section(const int nloops, const int udl, const int nd

    preempt_disable();
    for (i = nloops; i >= 0; i--) {
    - spin_lock(&test_lock);
    + raw_spin_lock(&test_lock);
    un_delay(udl, ndl);
    - spin_unlock(&test_lock);
    + raw_spin_unlock(&test_lock);
    }
    preempt_enable();
    }
    @@ -427,8 +427,8 @@ static void ref_lock_irq_section(const int nloops)

    preempt_disable();
    for (i = nloops; i >= 0; i--) {
    - spin_lock_irqsave(&test_lock, flags);
    - spin_unlock_irqrestore(&test_lock, flags);
    + raw_spin_lock_irqsave(&test_lock, flags);
    + raw_spin_unlock_irqrestore(&test_lock, flags);
    }
    preempt_enable();
    }
    @@ -440,9 +440,9 @@ static void ref_lock_irq_delay_section(const int nloops, const int udl, const in

    preempt_disable();
    for (i = nloops; i >= 0; i--) {
    - spin_lock_irqsave(&test_lock, flags);
    + raw_spin_lock_irqsave(&test_lock, flags);
    un_delay(udl, ndl);
    - spin_unlock_irqrestore(&test_lock, flags);
    + raw_spin_unlock_irqrestore(&test_lock, flags);
    }
    preempt_enable();
    }
    --
    2.35.1
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