If removal of a SCSI device has been triggered via sysfs that
device may still be in state SDEV_CANCEL if scsi_remove_host()
is invoked later on and after scsi_remove_host() returns.
SCSI LLDs may start cleaning up host resources needed by their
queuecommand() callback as soon as scsi_remove_host() finished.
Hence scsi_remove_host() must wait until blk_cleanup_queue()
for all devices associated with the host has finished. That
avoids that queuecommand() gets invoked after scsi_remove_host()
finished.
Signed-off-by: Bart Van Assche <bvanass...@acm.org>
Cc: Tejun Heo <t...@kernel.org>
Cc: James Bottomley <jbottom...@parallels.com>
Cc: Mike Christie <micha...@cs.wisc.edu>
Cc: Hannes Reinecke <h...@suse.de>
---
drivers/scsi/hosts.c | 30 ++++++++++++++++++++++++++++++
drivers/scsi/scsi_priv.h | 1 +
drivers/scsi/scsi_sysfs.c | 1 +
include/scsi/scsi_host.h | 1 +
4 files changed, 33 insertions(+)
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 6ae16cd..b68a013 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -150,12 +150,31 @@ int scsi_host_set_state(struct Scsi_Host *shost, enum
scsi_host_state state)
}
EXPORT_SYMBOL(scsi_host_set_state);
+/* Return true if and only if scsi_remove_host() is allowed to finish. */
+static bool scsi_remove_host_done(struct Scsi_Host *shost)
+{
+ lockdep_assert_held(shost->host_lock);
+
+ return list_empty(&shost->__devices);
+}
+
+/* Test whether scsi_remove_host() may finish, and if so, wake it up. */
+void scsi_check_remove_host_done(struct Scsi_Host *shost)
+{
+ lockdep_assert_held(shost->host_lock);
+
+ if (scsi_remove_host_done(shost))
+ wake_up(&shost->remove_host);
+}
+
/**
* scsi_remove_host - remove a scsi host
* @shost: a pointer to a scsi host to remove
**/
void scsi_remove_host(struct Scsi_Host *shost)
{
+ DEFINE_WAIT(wait);
+
mutex_lock(&shost->scan_mutex);
spin_lock_irq(shost->host_lock);
if (scsi_host_set_state(shost, SHOST_CANCEL))
@@ -174,6 +193,16 @@ void scsi_remove_host(struct Scsi_Host *shost)
spin_lock_irq(shost->host_lock);
if (scsi_host_set_state(shost, SHOST_DEL))
BUG_ON(scsi_host_set_state(shost, SHOST_DEL_RECOVERY));
+ while (!scsi_remove_host_done(shost)) {
+ prepare_to_wait_exclusive(&shost->remove_host, &wait,
+ TASK_INTERRUPTIBLE);
+ if (scsi_remove_host_done(shost))
+ break;
+ spin_unlock_irq(shost->host_lock);
+ schedule();
+ spin_lock_irq(shost->host_lock);
+ }
+ finish_wait(&shost->remove_host, &wait);
spin_unlock_irq(shost->host_lock);
transport_unregister_device(&shost->shost_gendev);
@@ -349,6 +378,7 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template
*sht, int privsize)
shost->shost_state = SHOST_CREATED;
INIT_LIST_HEAD(&shost->__devices);
INIT_LIST_HEAD(&shost->__targets);
+ init_waitqueue_head(&shost->remove_host);
INIT_LIST_HEAD(&shost->eh_cmd_q);
INIT_LIST_HEAD(&shost->starved_list);
init_waitqueue_head(&shost->host_wait);
diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h
index 8f9a0ca..882c823 100644
--- a/drivers/scsi/scsi_priv.h
+++ b/drivers/scsi/scsi_priv.h
@@ -26,6 +26,7 @@ struct scsi_nl_hdr;
/* hosts.c */
extern int scsi_init_hosts(void);
extern void scsi_exit_hosts(void);
+extern void scsi_check_remove_host_done(struct Scsi_Host *shost);
/* scsi.c */
extern int scsi_dispatch_cmd(struct scsi_cmnd *cmd);
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 7c1935b..bd51d65 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -345,6 +345,7 @@ static void scsi_device_dev_release_usercontext(struct
work_struct *work)
starget->reap_ref++;
list_del(&sdev->siblings);
list_del(&sdev->same_target_siblings);
+ scsi_check_remove_host_done(sdev->host);
spin_unlock_irqrestore(sdev->host->host_lock, flags);
cancel_work_sync(&sdev->event_work);
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 4908480..1b7fd89 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -577,6 +577,7 @@ struct Scsi_Host {
struct completion * eh_action; /* Wait for specific actions on the
host. */
wait_queue_head_t host_wait;
+ wait_queue_head_t remove_host;
struct scsi_host_template *hostt;
struct scsi_transport_template *transportt;
--
1.7.10.4
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