diff options
| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2022-04-10 15:49:36 +0300 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2022-04-13 22:32:21 +0300 |
| commit | 75d8cce128c516fe6cf4b8683e8fe1a59e919902 (patch) | |
| tree | c90aa58d0e8ae63b4915d5af63c63ebc499fb561 /lib | |
| parent | ce522ba9ef7e2d9fb22a39eb3371c0c64e2a433e (diff) | |
| download | linux-75d8cce128c516fe6cf4b8683e8fe1a59e919902.tar.xz | |
lib/irq_poll: Prevent softirq pending leak in irq_poll_cpu_dead()
irq_poll_cpu_dead() pulls the blk_cpu_iopoll backlog from the dead CPU and
raises the POLL softirq with __raise_softirq_irqoff() on the CPU it is
running on. That just sets the bit in the pending softirq mask.
This means the handling of the softirq is delayed until the next interrupt
or a local_bh_disable/enable() pair. As a consequence the CPU on which this
code runs can reach idle with the POLL softirq pending, which triggers a
warning in the NOHZ idle code.
Add a local_bh_disable/enable() pair around the interrupts disabled section
in irq_poll_cpu_dead(). local_bh_enable will handle the pending softirq.
[tglx: Massaged changelog and comment]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/87k0bxgl27.ffs@tglx
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/irq_poll.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/lib/irq_poll.c b/lib/irq_poll.c index 2f17b488d58e..2d5329a42105 100644 --- a/lib/irq_poll.c +++ b/lib/irq_poll.c @@ -188,14 +188,18 @@ EXPORT_SYMBOL(irq_poll_init); static int irq_poll_cpu_dead(unsigned int cpu) { /* - * If a CPU goes away, splice its entries to the current CPU - * and trigger a run of the softirq + * If a CPU goes away, splice its entries to the current CPU and + * set the POLL softirq bit. The local_bh_disable()/enable() pair + * ensures that it is handled. Otherwise the current CPU could + * reach idle with the POLL softirq pending. */ + local_bh_disable(); local_irq_disable(); list_splice_init(&per_cpu(blk_cpu_iopoll, cpu), this_cpu_ptr(&blk_cpu_iopoll)); __raise_softirq_irqoff(IRQ_POLL_SOFTIRQ); local_irq_enable(); + local_bh_enable(); return 0; } |