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 66dc14cf5687..f72ddca5180f 100644 --- a/kernel/rcu/refscale.c +++ b/kernel/rcu/refscale.c @@ -363,7 +363,7 @@ 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) { @@ -371,8 +371,8 @@ 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(); } @@ -383,9 +383,9 @@ 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(); } @@ -405,8 +405,8 @@ 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(); } @@ -418,9 +418,9 @@ 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(); }