diff options
| author | Ming Lei <ming.lei@redhat.com> | 2020-10-10 11:25:39 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-11-10 10:22:20 +0100 |
| commit | cba7a192c1e17ae7e74e2d7ecc73e9ea5a48faaf (patch) | |
| tree | f3c83398fe479075d9cc7cffdf9e9a031da45e58 /drivers/scsi/scsi_scan.c | |
| parent | 9c9fab488cf7364df658e9accb4ec0d34906b603 (diff) | |
scsi: core: Don't start concurrent async scan on same host
[ Upstream commit 831e3405c2a344018a18fcc2665acc5a38c3a707 ]
The current scanning mechanism is supposed to fall back to a synchronous
host scan if an asynchronous scan is in progress. However, this rule isn't
strictly respected, scsi_prep_async_scan() doesn't hold scan_mutex when
checking shost->async_scan. When scsi_scan_host() is called concurrently,
two async scans on same host can be started and a hang in do_scan_async()
is observed.
Fixes this issue by checking & setting shost->async_scan atomically with
shost->scan_mutex.
Link: https://lore.kernel.org/r/20201010032539.426615-1-ming.lei@redhat.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Lee Duncan <lduncan@suse.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/scsi/scsi_scan.c')
| -rw-r--r-- | drivers/scsi/scsi_scan.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c index 3e2288af56bc..647a057a9b6c 100644 --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -1710,15 +1710,16 @@ static void scsi_sysfs_add_devices(struct Scsi_Host *shost) */ static struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost) { - struct async_scan_data *data; + struct async_scan_data *data = NULL; unsigned long flags; if (strncmp(scsi_scan_type, "sync", 4) == 0) return NULL; + mutex_lock(&shost->scan_mutex); if (shost->async_scan) { shost_printk(KERN_DEBUG, shost, "%s called twice\n", __func__); - return NULL; + goto err; } data = kmalloc(sizeof(*data), GFP_KERNEL); @@ -1729,7 +1730,6 @@ 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); @@ -1744,6 +1744,7 @@ static struct async_scan_data *scsi_prep_async_scan(struct Scsi_Host *shost) return data; err: + mutex_unlock(&shost->scan_mutex); kfree(data); return NULL; } |