Commit e6a43aeb authored by Zqiang's avatar Zqiang Committed by Paul E. McKenney
Browse files

srcu/tiny: Remove preempt_disable/enable() in srcu_gp_start_if_needed() 



Currently, the srcu_gp_start_if_needed() is always be invoked in
preempt disable's critical section, this commit therefore remove
redundant preempt_disable/enable() in srcu_gp_start_if_needed()
and adds a call to lockdep_assert_preemption_disabled() in order
to enable lockdep to diagnose mistaken invocations of this function
from preempts-enabled code.

Fixes: 65b4a595 ("srcu: Make Tiny SRCU explicitly disable preemption")
Signed-off-by: default avatarZqiang <qiang.zhang@linux.dev>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 1c77e862

kernel/rcu/srcutiny.c

+1 −3
Original line number Diff line number Diff line
@@ -176,10 +176,9 @@ static void srcu_gp_start_if_needed(struct srcu_struct *ssp) 
{

	unsigned long cookie;



	preempt_disable();  // Needed for PREEMPT_LAZY

	lockdep_assert_preemption_disabled(); // Needed for PREEMPT_LAZY

	cookie = get_state_synchronize_srcu(ssp);

	if (ULONG_CMP_GE(READ_ONCE(ssp->srcu_idx_max), cookie)) {

		preempt_enable();

		return;

	}

	WRITE_ONCE(ssp->srcu_idx_max, cookie);
@@ -189,7 +188,6 @@ static void srcu_gp_start_if_needed(struct srcu_struct *ssp) 
		else if (list_empty(&ssp->srcu_work.entry))

			list_add(&ssp->srcu_work.entry, &srcu_boot_list);

	}

	preempt_enable();

}



/*