Re: [PATCH] scsi: lpfc: Fix a possible data race in lpfc_unregister_fcf_rescan()
From: Laurence Oberman
Date: Wed Jul 05 2023 - 10:36:01 EST
On Fri, 2023-06-30 at 10:47 +0800, Tuo Li wrote:
> The variable phba->fcf.fcf_flag is often protected by the lock
> phba->hbalock() when is accessed. Here is an example in
> lpfc_unregister_fcf_rescan():
>
> spin_lock_irq(&phba->hbalock);
> phba->fcf.fcf_flag |= FCF_INIT_DISC;
> spin_unlock_irq(&phba->hbalock);
>
> However, in the same function, phba->fcf.fcf_flag is assigned with 0
> without holding the lock, and thus can cause a data race:
>
> phba->fcf.fcf_flag = 0;
>
> To fix this possible data race, a lock and unlock pair is added when
> accessing the variable phba->fcf.fcf_flag.
>
> Reported-by: BassCheck <bass@xxxxxxxxxxx>
> Signed-off-by: Tuo Li <islituo@xxxxxxxxx>
> ---
> drivers/scsi/lpfc/lpfc_hbadisc.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/scsi/lpfc/lpfc_hbadisc.c
> b/drivers/scsi/lpfc/lpfc_hbadisc.c
> index 5ba3a9ad9501..9d2feb69cae7 100644
> --- a/drivers/scsi/lpfc/lpfc_hbadisc.c
> +++ b/drivers/scsi/lpfc/lpfc_hbadisc.c
> @@ -6961,7 +6961,9 @@ lpfc_unregister_fcf_rescan(struct lpfc_hba
> *phba)
> if (rc)
> return;
> /* Reset HBA FCF states after successful unregister FCF */
> + spin_lock_irq(&phba->hbalock);
> phba->fcf.fcf_flag = 0;
> + spin_unlock_irq(&phba->hbalock);
> phba->fcf.current_rec.flag = 0;
>
> /*
This makes sense and looks good to me
Reviewed-by: Laurence Oberman <loberman@xxxxxxxxxx>