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authorHannes Reinecke <hare@suse.de>2020-09-24 12:45:59 +0200
committerMartin K. Petersen <martin.petersen@oracle.com>2020-11-02 18:09:49 -0500
commit5faf50e9e9fdc2117c61ff7e20da49cd6a29e0ca (patch)
treeabbe157a8252e3270e0569fe61c3bab1a7735998 /drivers/scsi/device_handler
parentaf61bc1e33d2c0ec22612b46050f5b58ac56a962 (diff)
scsi: scsi_dh_alua: Avoid crash during alua_bus_detach()
alua_bus_detach() might be running concurrently with alua_rtpg_work(), so we might trip over h->sdev == NULL and call BUG_ON(). The correct way of handling it is to not set h->sdev to NULL in alua_bus_detach(), and call rcu_synchronize() before the final delete to ensure that all concurrent threads have left the critical section. Then we can get rid of the BUG_ON() and replace it with a simple if condition. Link: https://lore.kernel.org/r/1600167537-12509-1-git-send-email-jitendra.khasdev@oracle.com Link: https://lore.kernel.org/r/20200924104559.26753-1-hare@suse.de Cc: Brian Bunker <brian@purestorage.com> Acked-by: Brian Bunker <brian@purestorage.com> Tested-by: Jitendra Khasdev <jitendra.khasdev@oracle.com> Reviewed-by: Jitendra Khasdev <jitendra.khasdev@oracle.com> Signed-off-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi/device_handler')
-rw-r--r--drivers/scsi/device_handler/scsi_dh_alua.c9
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index f32da0ca529e..308bda2e9c00 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -658,8 +658,8 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
rcu_read_lock();
list_for_each_entry_rcu(h,
&tmp_pg->dh_list, node) {
- /* h->sdev should always be valid */
- BUG_ON(!h->sdev);
+ if (!h->sdev)
+ continue;
h->sdev->access_state = desc[0];
}
rcu_read_unlock();
@@ -705,7 +705,8 @@ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg)
pg->expiry = 0;
rcu_read_lock();
list_for_each_entry_rcu(h, &pg->dh_list, node) {
- BUG_ON(!h->sdev);
+ if (!h->sdev)
+ continue;
h->sdev->access_state =
(pg->state & SCSI_ACCESS_STATE_MASK);
if (pg->pref)
@@ -1147,7 +1148,6 @@ static void alua_bus_detach(struct scsi_device *sdev)
spin_lock(&h->pg_lock);
pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock));
rcu_assign_pointer(h->pg, NULL);
- h->sdev = NULL;
spin_unlock(&h->pg_lock);
if (pg) {
spin_lock_irq(&pg->lock);
@@ -1156,6 +1156,7 @@ static void alua_bus_detach(struct scsi_device *sdev)
kref_put(&pg->kref, release_port_group);
}
sdev->handler_data = NULL;
+ synchronize_rcu();
kfree(h);
}