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authorMing Lei <ming.lei@redhat.com>2020-10-10 11:25:39 +0800
committerMartin K. Petersen <martin.petersen@oracle.com>2020-10-26 16:05:34 -0400
commit831e3405c2a344018a18fcc2665acc5a38c3a707 (patch)
tree55edf7cfc12446727e86994b307d4c4b413f828d
parent3650b228f83adda7e5ee532e2b90429c03f7b9ec (diff)
downloadlinux-831e3405c2a344018a18fcc2665acc5a38c3a707.tar.bz2
scsi: core: Don't start concurrent async scan on same host
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>
-rw-r--r--drivers/scsi/scsi_scan.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index f2437a7570ce..9af50e6f94c4 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -1714,15 +1714,16 @@ 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);
@@ -1733,7 +1734,6 @@ 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);
@@ -1748,6 +1748,7 @@ 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;
}