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scsi: core: Revert "Simplify LLD module reference counting" 

Revert the patch series "Call blk_mq_free_tag_set() earlier" because it
introduces a deadlock if the scsi_remove_host() caller holds a reference on
a device, target or host.

Link: https://lore.kernel.org/r/20220821220502.13685-3-bvanassche@acm.org
Fixes: 1a9283782d ("scsi: core: Simplify LLD module reference counting")
Reported-by: syzbot+bafeb834708b1bb750bc@syzkaller.appspotmail.com
Tested-by: Kenneth R. Crudup <kenny@panix.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Bart Van Assche 2022-08-21 15:05:00 -07:00 committed by Martin K. Petersen
parent 2b36209ca8
commit 70e8d057be
2 changed files with 12 additions and 6 deletions
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9
drivers/scsi/scsi.c
View File

@ -586,13 +586,10 @@ EXPORT_SYMBOL(scsi_device_get);
*/
void scsi_device_put(struct scsi_device *sdev)
{
/*
* Decreasing the module reference count before the device reference
* count is safe since scsi_remove_host() only returns after all
* devices have been removed.
*/
module_put(sdev->host->hostt->module);
struct module *mod = sdev->host->hostt->module;
put_device(&sdev->sdev_gendev);
module_put(mod);
}
EXPORT_SYMBOL(scsi_device_put);

9
drivers/scsi/scsi_sysfs.c
View File

@ -452,6 +452,9 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
struct scsi_vpd *vpd_pg0 = NULL, *vpd_pg89 = NULL;
struct scsi_vpd *vpd_pgb0 = NULL, *vpd_pgb1 = NULL, *vpd_pgb2 = NULL;
unsigned long flags;
struct module *mod;
mod = sdev->host->hostt->module;
scsi_dh_release_device(sdev);
@ -518,11 +521,17 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
if (parent)
put_device(parent);
module_put(mod);
}
static void scsi_device_dev_release(struct device *dev)
{
struct scsi_device *sdp = to_scsi_device(dev);
/* Set module pointer as NULL in case of module unloading */
if (!try_module_get(sdp->host->hostt->module))
sdp->host->hostt->module = NULL;
execute_in_process_context(scsi_device_dev_release_usercontext,
&sdp->ew);
}