[GIT PULL] IRQ fix

From: Ingo Molnar
Date: Sun May 05 2024 - 05:06:57 EST


Linus,

Please pull the latest irq/urgent Git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git irq-urgent-2024-05-05

# HEAD: 1dd1eff161bd55968d3d46bc36def62d71fb4785 softirq: Fix suspicious RCU usage in __do_softirq()

Fix suspicious RCU usage in __do_softirq().

Thanks,

Ingo

------------------>
Zqiang (1):
softirq: Fix suspicious RCU usage in __do_softirq()


kernel/softirq.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/kernel/softirq.c b/kernel/softirq.c
index b315b21fb28c..02582017759a 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -508,7 +508,7 @@ static inline bool lockdep_softirq_start(void) { return false; }
static inline void lockdep_softirq_end(bool in_hardirq) { }
#endif

-asmlinkage __visible void __softirq_entry __do_softirq(void)
+static void handle_softirqs(bool ksirqd)
{
unsigned long end = jiffies + MAX_SOFTIRQ_TIME;
unsigned long old_flags = current->flags;
@@ -563,8 +563,7 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
pending >>= softirq_bit;
}

- if (!IS_ENABLED(CONFIG_PREEMPT_RT) &&
- __this_cpu_read(ksoftirqd) == current)
+ if (!IS_ENABLED(CONFIG_PREEMPT_RT) && ksirqd)
rcu_softirq_qs();

local_irq_disable();
@@ -584,6 +583,11 @@ asmlinkage __visible void __softirq_entry __do_softirq(void)
current_restore_flags(old_flags, PF_MEMALLOC);
}

+asmlinkage __visible void __softirq_entry __do_softirq(void)
+{
+ handle_softirqs(false);
+}
+
/**
* irq_enter_rcu - Enter an interrupt context with RCU watching
*/
@@ -921,7 +925,7 @@ static void run_ksoftirqd(unsigned int cpu)
* We can safely run softirq on inline stack, as we are not deep
* in the task stack here.
*/
- __do_softirq();
+ handle_softirqs(true);
ksoftirqd_run_end();
cond_resched();
return;