From dd64f80587190265ca8a0f4be6c64c2fda6d3ac2 Mon Sep 17 00:00:00 2001 From: Chengfeng Ye Date: Wed, 26 Jul 2023 12:56:55 +0000 Subject: scsi: qedi: Fix potential deadlock on &qedi_percpu->p_work_lock As &qedi_percpu->p_work_lock is acquired by hard IRQ qedi_msix_handler(), other acquisitions of the same lock under process context should disable IRQ, otherwise deadlock could happen if the IRQ preempts the execution while the lock is held in process context on the same CPU. qedi_cpu_offline() is one such function which acquires the lock in process context. [Deadlock Scenario] qedi_cpu_offline() ->spin_lock(&p->p_work_lock) ->qedi_msix_handler() ->edi_process_completions() ->spin_lock_irqsave(&p->p_work_lock, flags); (deadlock here) This flaw was found by an experimental static analysis tool I am developing for IRQ-related deadlocks. The tentative patch fix the potential deadlock by spin_lock_irqsave() under process context. Signed-off-by: Chengfeng Ye Link: https://lore.kernel.org/r/20230726125655.4197-1-dg573847474@gmail.com Acked-by: Manish Rangankar Signed-off-by: Martin K. Petersen --- drivers/scsi/qedi/qedi_main.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'drivers/scsi/qedi') diff --git a/drivers/scsi/qedi/qedi_main.c b/drivers/scsi/qedi/qedi_main.c index 450522b204d6..77a56a136678 100644 --- a/drivers/scsi/qedi/qedi_main.c +++ b/drivers/scsi/qedi/qedi_main.c @@ -1976,8 +1976,9 @@ static int qedi_cpu_offline(unsigned int cpu) struct qedi_percpu_s *p = this_cpu_ptr(&qedi_percpu); struct qedi_work *work, *tmp; struct task_struct *thread; + unsigned long flags; - spin_lock_bh(&p->p_work_lock); + spin_lock_irqsave(&p->p_work_lock, flags); thread = p->iothread; p->iothread = NULL; @@ -1988,7 +1989,7 @@ static int qedi_cpu_offline(unsigned int cpu) kfree(work); } - spin_unlock_bh(&p->p_work_lock); + spin_unlock_irqrestore(&p->p_work_lock, flags); if (thread) kthread_stop(thread); return 0; -- cgit