[PATCH 42/78] sd: use __register_blkdev to avoid a modprobe for an unregistered dev_t

[Christoph Hellwig <hch@xxxxxx>]

Switch from using blk_register_region to the probe callback passed to
__register_blkdev to disable the request_module call for an unclaimed
dev_t in the SD majors.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
---
 drivers/scsi/sd.c | 19 +++++--------------
 1 file changed, 5 insertions(+), 14 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index a2a4f385833d6c..679c2c02504763 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -630,13 +630,11 @@ static struct scsi_driver sd_template = {
 };
 
 /*
- * Dummy kobj_map->probe function.
- * The default ->probe function will call modprobe, which is
- * pointless as this module is already loaded.
+ * Don't request a new module, as that could deadlock in multipath
+ * environment.
  */
-static struct kobject *sd_default_probe(dev_t devt, int *partno, void *data)
+static void sd_default_probe(dev_t devt)
 {
-       return NULL;
 }
 
 /*
@@ -3525,9 +3523,6 @@ static int sd_remove(struct device *dev)
 
        free_opal_dev(sdkp->opal_dev);
 
-       blk_register_region(devt, SD_MINORS, NULL,
-                           sd_default_probe, NULL, NULL);
-
        mutex_lock(&sd_ref_mutex);
        dev_set_drvdata(dev, NULL);
        put_device(&sdkp->dev);
@@ -3717,11 +3712,9 @@ static int __init init_sd(void)
        SCSI_LOG_HLQUEUE(3, printk("init_sd: sd driver entry point\n"));
 
        for (i = 0; i < SD_MAJORS; i++) {
-               if (register_blkdev(sd_major(i), "sd") != 0)
+               if (__register_blkdev(sd_major(i), "sd", sd_default_probe))
                        continue;
                majors++;
-               blk_register_region(sd_major(i), SD_MINORS, NULL,
-                                   sd_default_probe, NULL, NULL);
        }
 
        if (!majors)
@@ -3794,10 +3787,8 @@ static void __exit exit_sd(void)
 
        class_unregister(&sd_disk_class);
 
-       for (i = 0; i < SD_MAJORS; i++) {
-               blk_unregister_region(sd_major(i), SD_MINORS);
+       for (i = 0; i < SD_MAJORS; i++)
                unregister_blkdev(sd_major(i), "sd");
-       }
 }
 
 module_init(init_sd);
-- 
2.29.2