The following commit has been merged into the irq/core branch of tip:
Commit-ID: e739f98b4b11337a4e3865364b8922a9e5ad32b6
Gitweb: https://git.kernel.org/tip/e739f98b4b11337a4e3865364b8922a9e5ad32b6
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Tue, 10 Nov 2020 12:38:48 +01:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Fri, 17 Sep 2021 15:08:22 +02:00
genirq: Move prio assignment into the newly created thread
With enabled threaded interrupts the nouveau driver reported the
following:
| Chain exists of:
| &mm->mmap_lock#2 --> &device->mutex --> &cpuset_rwsem
|
| Possible unsafe locking scenario:
|
| CPU0 CPU1
| ---- ----
| lock(&cpuset_rwsem);
| lock(&device->mutex);
| lock(&cpuset_rwsem);
| lock(&mm->mmap_lock#2);
The device->mutex is nvkm_device::mutex.
Unblocking the lockchain at `cpuset_rwsem' is probably the easiest
thing to do. Move the priority assignment to the start of the newly
created thread.
Fixes: 710da3c8ea7df ("sched/core: Prevent race condition between cpuset and __sched_setscheduler()")
Reported-by: Mike Galbraith <efault@xxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
[bigeasy: Patch description]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/a23a826af7c108ea5651e73b8fbae5e653f16e86.camel@xxxxxx
---
kernel/irq/manage.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index b392483..7405e38 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1259,6 +1259,8 @@ static int irq_thread(void *data)
irqreturn_t (*handler_fn)(struct irq_desc *desc,
struct irqaction *action);
+ sched_set_fifo(current);
+
if (force_irqthreads() && test_bit(IRQTF_FORCED_THREAD,
&action->thread_flags))
handler_fn = irq_forced_thread_fn;
@@ -1424,8 +1426,6 @@ setup_irq_thread(struct irqaction *new, unsigned int irq, bool secondary)
if (IS_ERR(t))
return PTR_ERR(t);
- sched_set_fifo(t);
-
/*
* We keep the reference to the task struct even if
* the thread dies to avoid that the interrupt code
|