when a scsi_device is unpluged from scsi controller, if the
scsi_device is still be used by application layer,it won't be
released until users release it. In this case, scsi_device_remove just set
the scsi_device's state to be SDEV_DEL. But if you plug the disk
just before the old scsi_device is released, then there will be two
scsi_device structures in scsi_host->__devices. when the next unpluging
event happens,some low-level drivers will check whether the scsi_device
has been added to host (for example, the megaraid sas series controller)
by calling scsi_device_lookup(call __scsi_device_lookup).
__scsi_device_lookup will return the first scsi_device. Because its
state is SDEV_DEL, the scsi_device_lookup will return NULL finally,
making the low-level driver assume that the scsi_device has been
removed,and won't call scsi_device_remove,which will lead the
failure of hot swap.
Signed-off-by: Zhengping Zhou <johnzzpcrystal@xxxxxxxxx>
---
Hi all:
I find a bug about the failure of hot swap when I am using
megaraid sas series controller. Finally I have found that
when controller receives the event of hot swap, it will firstly
check whether the device is added to the system/host by calling
scsi_device_lookup.The logics in function megasas_aen_polling
is as follows:
case MR_EVT_PD_REMOVED:
if (megasas_get_pd_list(instance) == 0) {
for (i = 0; i < MEGASAS_MAX_PD_CHANNELS; i++) {
for (j = 0;
j < MEGASAS_MAX_DEV_PER_CHANNEL;
j++) {
pd_index =
(i * MEGASAS_MAX_DEV_PER_CHANNEL) + j;
sdev1 = scsi_device_lookup(host, i, j, 0);
if (instance->pd_list[pd_index].driveState
== MR_PD_STATE_SYSTEM) {
if (sdev1)
scsi_device_put(sdev1);
} else {
if (sdev1) {
scsi_remove_device(sdev1);
scsi_device_put(sdev1);
}
}
}
}
}
If the previous scsi_device is not released, this will lead the
appearance of two scsi_devices which correspond with the same disk.
And when the disk is unpluged afterwards, the controller will assume
that this disk has never been added into the system/host. Thus it won't
call scsi_device_remove. When I finish this modification, this problem
is fixed.So far, I have successfully test PCI_DEVICE_ID_LSI_SAS0073SKINNY
and PCI_DEVICE_ID_LSI_FURY.
Thanks
Zhengping
---
drivers/scsi/scsi.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 207d6a7..5251d6d 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -1118,6 +1118,8 @@ struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
struct scsi_device *sdev;
list_for_each_entry(sdev, &shost->__devices, siblings) {
+ if (sdev->sdev_state == SDEV_DEL)
+ continue;
if (sdev->channel == channel && sdev->id == id &&
sdev->lun ==lun)
return sdev;
--
1.8.3.1
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