[PATCHv2] s390/irq: utilize RCU instead of irq_lock_sparse() in show_msi_interrupt()

Pingfan Liu
2022-04-22T10:02:38Z

As demonstrated by commit 74bdf7815dfb ("genirq: Speedup show_interrupts()"),
irq_desc can be accessed safely in RCU read section.

Hence here resorting to rcu read lock to get rid of irq_lock_sparse().

Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-kernel@vger.kernel.org
To: linux-s390@vger.kernel.org

---
arch/s390/kernel/irq.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/s390/kernel/irq.c b/arch/s390/kernel/irq.c
index 3033f616e256..45393919fe61 100644
--- a/arch/s390/kernel/irq.c
+++ b/arch/s390/kernel/irq.c
@@ -205,7 +205,7 @@ static void show_msi_interrupt(struct seq_file *p, int irq)
unsigned long flags;
int cpu;

- irq_lock_sparse();
+ rcu_read_lock();
desc = irq_to_desc(irq);
if (!desc)
goto out;
@@ -224,7 +224,7 @@ static void show_msi_interrupt(struct seq_file *p, int irq)
seq_putc(p, '\n');
raw_spin_unlock_irqrestore(&desc->lock, flags);
out:
- irq_unlock_sparse();
+ rcu_read_unlock();
}

/*
--
2.31.1