From: Sebastian Andrzej Siewior Date: Tue, 19 Feb 2019 16:49:29 +0100 Subject: [PATCH 127/290] softirq: Avoid "local_softirq_pending" messages if task is in cpu_chill() Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=35dcb7fcc7ec0b10e0b649f1e1ea2a63a965dac2 If the softirq thread enters cpu_chill() then ->state is UNINTERRUPTIBLE and has no ->pi_blocked_on set and so its mask is not taken into account. ->sleeping_lock is increased by cpu_chill() since it is also requried to avoid a splat by RCU in case cpu_chill() is used while a RCU-read lock is held. Use the same mechanism for the softirq-pending check. Cc: stable-rt@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior --- kernel/softirq.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/softirq.c b/kernel/softirq.c index 1920985eeb09..27a4bb2303d0 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -105,9 +105,12 @@ static bool softirq_check_runner_tsk(struct task_struct *tsk, * _before_ it sets pi_blocked_on to NULL under * tsk->pi_lock. So we need to check for both: state * and pi_blocked_on. + * The test against UNINTERRUPTIBLE + ->sleeping_lock is in case the + * task does cpu_chill(). */ raw_spin_lock(&tsk->pi_lock); - if (tsk->pi_blocked_on || tsk->state == TASK_RUNNING) { + if (tsk->pi_blocked_on || tsk->state == TASK_RUNNING || + (tsk->state == TASK_UNINTERRUPTIBLE && tsk->sleeping_lock)) { /* Clear all bits pending in that task */ *pending &= ~(tsk->softirqs_raised); ret = true;