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SubjectRe: [PATCH] scsi: shost->async_scan should be protected by mutex_lock
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On 09/07/2017 11:54 PM, Ouyangzhaowei (Charles) wrote:
> shost->async_scan should be protected by mutex_lock, otherwise the check
> of "called twice" won't work.
>
> Signed-off-by: Ouyang Zhaowei <ouyangzhaowei@huawei.com>
> ---
> drivers/scsi/scsi_scan.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
> index fd88dab..1d1df51 100644
> --- a/drivers/scsi/scsi_scan.c
> +++ b/drivers/scsi/scsi_scan.c
> @@ -1722,6 +1722,7 @@ static struct async_scan_data
> *scsi_prep_async_scan(struct Scsi_Host *shost)
> if (strncmp(scsi_scan_type, "sync", 4) == 0)
> return NULL;
>
> + mutex_lock(&shost->scan_mutex);

The mutex will not be unlocked in the event that either the host has called
scsi_prep_async_scan() twice, or a condition is meet the branches to the "err" label prior
to where the original mutex_lock() was located below.

-Tyrel

> if (shost->async_scan) {
> shost_printk(KERN_DEBUG, shost, "%s called twice\n",
> __func__);
> return NULL;
> @@ -1735,7 +1736,6 @@ static struct async_scan_data
> *scsi_prep_async_scan(struct Scsi_Host *shost)
> goto err;
> init_completion(&data->prev_finished);
>
> - mutex_lock(&shost->scan_mutex);
> spin_lock_irqsave(shost->host_lock, flags);
> shost->async_scan = 1;
> spin_unlock_irqrestore(shost->host_lock, flags);
>

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