From 728b478d2d358480b333b42d0e10e0fecb20114c Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 9 Mar 2021 09:55:53 +0100 Subject: softirq: Add RT specific softirq accounting RT requires the softirq processing and local bottomhalf disabled regions to be preemptible. Using the normal preempt count based serialization is therefore not possible because this implicitely disables preemption. RT kernels use a per CPU local lock to serialize bottomhalfs. As local_bh_disable() can nest the lock can only be acquired on the outermost invocation of local_bh_disable() and released when the nest count becomes zero. Tasks which hold the local lock can be preempted so its required to keep track of the nest count per task. Add a RT only counter to task struct and adjust the relevant macros in preempt.h. Signed-off-by: Thomas Gleixner Tested-by: Sebastian Andrzej Siewior Tested-by: Paul E. McKenney Reviewed-by: Frederic Weisbecker Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20210309085726.983627589@linutronix.de --- include/linux/preempt.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'include/linux/preempt.h') diff --git a/include/linux/preempt.h b/include/linux/preempt.h index 69cc8b64aa3a..9881eac0698f 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -79,7 +79,11 @@ #define nmi_count() (preempt_count() & NMI_MASK) #define hardirq_count() (preempt_count() & HARDIRQ_MASK) -#define softirq_count() (preempt_count() & SOFTIRQ_MASK) +#ifdef CONFIG_PREEMPT_RT +# define softirq_count() (current->softirq_disable_cnt & SOFTIRQ_MASK) +#else +# define softirq_count() (preempt_count() & SOFTIRQ_MASK) +#endif #define irq_count() (nmi_count() | hardirq_count() | softirq_count()) /* -- cgit v1.3-18-gd494