> -----Original Message----- > From: Chengfeng Ye <dg573847474@xxxxxxxxx> > Sent: Wednesday, July 26, 2023 6:27 PM > To: Nilesh Javali <njavali@xxxxxxxxxxx>; Manish Rangankar > <mrangankar@xxxxxxxxxxx>; GR-QLogic-Storage-Upstream <GR-QLogic- > Storage-Upstream@xxxxxxxxxxx>; jejb@xxxxxxxxxxxxx; > martin.petersen@xxxxxxxxxx > Cc: linux-scsi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Chengfeng Ye > <dg573847474@xxxxxxxxx> > Subject: [EXT] [PATCH] scsi: qedi: Fix potential deadlock on &qedi_percpu- > >p_work_lock > > External Email > > ---------------------------------------------------------------------- > As &qedi_percpu->p_work_lock is acquired by hard irq qedi_msix_handler(), > other acquisition of the same lock under process context should disable irq, > otherwise deadlock could happen if the irq preempt the execution while the > lock is held in process context on the same CPU. > > qedi_cpu_offline() is one such function acquires the lock on process context. > > [Deadlock Scenario] > qedi_cpu_offline() > ->spin_lock(&p->p_work_lock) > <irq> > ->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 deadlock. > > The tentative patch fix the potential deadlock by spin_lock_irqsave() under > process context. > > Signed-off-by: Chengfeng Ye <dg573847474@xxxxxxxxx> > --- > drivers/scsi/qedi/qedi_main.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > 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; > -- > 2.17.1 Thanks for the patch, Acked-by: Manish Rangankar <mrangankar@xxxxxxxxxxx>
