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scsi: core: Make sure that hosts outlive targets

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Fix the race conditions between SCSI LLD kernel module unloading and SCSI
device and target removal by making sure that SCSI hosts are destroyed
after all associated target and device objects have been freed.

Link: https://lore.kernel.org/r/20220728221851.1822295-3-bvanassche@acm.org
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Mike Christie <michael.christie@oracle.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: John Garry <john.garry@huawei.com>
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
[ bvanassche: Reworked Ming's patch and split it ]
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Ming Lei 2022-07-28 15:18:49 -07:00 committed by Martin K. Petersen
parent fe44260419
commit 16728aaba6
3 changed files with 18 additions and 0 deletions
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8
drivers/scsi/hosts.c
View file

@ -190,6 +190,13 @@ void scsi_remove_host(struct Scsi_Host *shost)
transport_unregister_device(&shost->shost_gendev);
device_unregister(&shost->shost_dev);
device_del(&shost->shost_gendev);
/*
* After scsi_remove_host() has returned the scsi LLD module can be
* unloaded and/or the host resources can be released. Hence wait until
* the dependent SCSI targets and devices are gone before returning.
*/
wait_event(shost->targets_wq, atomic_read(&shost->target_count) == 0);
}
EXPORT_SYMBOL(scsi_remove_host);
@ -394,6 +401,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
INIT_LIST_HEAD(&shost->starved_list);
init_waitqueue_head(&shost->host_wait);
mutex_init(&shost->scan_mutex);
init_waitqueue_head(&shost->targets_wq);
index = ida_alloc(&host_index_ida, GFP_KERNEL);
if (index < 0) {

7
drivers/scsi/scsi_scan.c
View file

@ -406,9 +406,14 @@ static void scsi_target_destroy(struct scsi_target *starget)
static void scsi_target_dev_release(struct device *dev)
{
struct device *parent = dev->parent;
struct Scsi_Host *shost = dev_to_shost(parent);
struct scsi_target *starget = to_scsi_target(dev);
kfree(starget);
if (atomic_dec_return(&shost->target_count) == 0)
wake_up(&shost->targets_wq);
put_device(parent);
}
@ -523,6 +528,8 @@ static struct scsi_target *scsi_alloc_target(struct device *parent,
starget->max_target_blocked = SCSI_DEFAULT_TARGET_BLOCKED;
init_waitqueue_head(&starget->sdev_wq);
atomic_inc(&shost->target_count);
retry:
spin_lock_irqsave(shost->host_lock, flags);

3
include/scsi/scsi_host.h
View file

@ -689,6 +689,9 @@ struct Scsi_Host {
/* ldm bits */
struct device shost_gendev, shost_dev;
atomic_t target_count;
wait_queue_head_t targets_wq;
/*
* Points to the transport data (if any) which is allocated
* separately