scsi: core: Fix the scsi_device_put() might_sleep annotation

Although most calls of scsi_device_put() happen from non-atomic context,
alua_rtpg_queue() calls this function from atomic context if
alua_rtpg_queue() itself is called from atomic context. alua_rtpg_queue()
is always called from contexts where the caller must hold at least one
reference to the scsi device in question. This means that the reference
taken by alua_rtpg_queue() itself can't be the last one, and thus can be
dropped without entering the code path in which scsi_device_put() might
actually sleep. Hence move the might_sleep() annotation from
scsi_device_put() into scsi_device_dev_release().

[1] https://lore.kernel.org/linux-scsi/b49e37d5-edfb-4c56-3eeb-62c7d5855c00@linux.ibm.com/
[2] https://lore.kernel.org/linux-scsi/55c35e64-a7d4-9072-46fd-e8eae6a90e96@linux.ibm.com/

Note: a significant part of the above description was written by Martin
Wilck.

Fixes: f93ed747e2c7 ("scsi: core: Release SCSI devices synchronously")
Cc: Martin Wilck <mwilck@suse.com>
Cc: Steffen Maier <maier@linux.ibm.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Sachin Sant <sachinp@linux.ibm.com>
Cc: Benjamin Block <bblock@linux.ibm.com>
Reported-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Martin Wilck <mwilck@suse.com>
Link: https://lore.kernel.org/r/20230125194311.249553-1-bvanassche@acm.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 1426b9b03612f9628e6e85af0484675ab8147f3a..9feb0323bc44a536703faa5801ccd587bcc1e5ab 100644 (file)
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -588,8 +588,6 @@ void scsi_device_put(struct scsi_device *sdev)
 {
        struct module *mod = sdev->host->hostt->module;
 
-       might_sleep();
-
        put_device(&sdev->sdev_gendev);
        module_put(mod);
 }

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 981d1bab21207166b97f0003830d069bb01ff615..8ef9a54943403a8c717ed64bbe44181a6bed1ece 100644 (file)
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -451,6 +451,8 @@ static void scsi_device_dev_release(struct device *dev)
        struct scsi_vpd *vpd_pgb0 = NULL, *vpd_pgb1 = NULL, *vpd_pgb2 = NULL;
        unsigned long flags;
 
+       might_sleep();
+
        scsi_dh_release_device(sdev);
 
        parent = sdev->sdev_gendev.parent;