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genirq: Change force_irqthreads to a static key

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With CONFIG_IRQ_FORCED_THREADING=y, testing the boolean force_irqthreads
could incur a cache line miss in invoke_softirq() and other places.

Replace the test with a static key to avoid the potential cache miss.

[ tglx: Dropped the IDE part, removed the export and updated blk-mq ]

Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Tanner Love <tannerlove@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210602180338.3324213-1-tannerlove.kernel@gmail.com
This commit is contained in:
Tanner Love
2021-06-02 14:03:38 -04:00
committed by Thomas Gleixner
parent 5a6c76b5de
commit 91cc470e79
4 changed files with 12 additions and 11 deletions
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8
include/linux/interrupt.h
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@@ -13,6 +13,7 @@
#include <linux/hrtimer.h>
#include <linux/kref.h>
#include <linux/workqueue.h>
#include <linux/jump_label.h>
#include <linux/atomic.h>
#include <asm/ptrace.h>
@@ -474,12 +475,13 @@ extern int irq_set_irqchip_state(unsigned int irq, enum irqchip_irq_state which,
#ifdef CONFIG_IRQ_FORCED_THREADING
# ifdef CONFIG_PREEMPT_RT
# define force_irqthreads (true)
# define force_irqthreads() (true)
# else
extern bool force_irqthreads;
DECLARE_STATIC_KEY_FALSE(force_irqthreads_key);
# define force_irqthreads() (static_branch_unlikely(&force_irqthreads_key))
# endif
#else
#define force_irqthreads (0)
#define force_irqthreads() (false)
#endif
#ifndef local_softirq_pending