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Subject[PATCH 1/2] x86/entry: Use should_resched() in idtentry_exit_cond_resched()
Date
The TIF_NEED_RESCHED bit is inlined on x86 into the preemption counter.
So instead checking the preemption counter against zero via
preempt_count() and later checking the TIF_NEED_RESCHED bit via
need_resched() we could use should_resched() which does both checks in
one go.
The functional difference is that we don't enter the if statement with
preempt_count == 0 and TIF_NEED_RESCHED not set.

Use should_resched() instead need_resched() + preempt_count().

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
arch/x86/entry/common.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index bd3f14175193c..212382f61b8e4 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -612,13 +612,12 @@ bool noinstr idtentry_enter_cond_rcu(struct pt_regs *regs)

static void idtentry_exit_cond_resched(struct pt_regs *regs, bool may_sched)
{
- if (may_sched && !preempt_count()) {
+ if (may_sched && should_resched(0)) {
/* Sanity check RCU and thread stack */
rcu_irq_exit_check_preempt();
if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
WARN_ON_ONCE(!on_thread_stack());
- if (need_resched())
- preempt_schedule_irq();
+ preempt_schedule_irq();
}
/* Covers both tracing and lockdep */
trace_hardirqs_on();
--
2.27.0
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