[PATCH 09/19] sd: use __register_blkdev to avoid a modprobe for an unregistered dev_t

Christoph Hellwig
2020-08-30T06:27:27Z

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@lst.de>
---
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 95018e650f2d0c..ece87b1aab1b78 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -596,13 +596,11 @@ 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;
}

/*
@@ -3479,9 +3477,6 @@ 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);
@@ -3671,11 +3666,9 @@ 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)
@@ -3748,10 +3741,8 @@ 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);
--
2.28.0