On 2022/11/18 17:18, John Garry wrote:
On 18/11/2022 03:11, Yang Yingliang wrote:
);
There is a slight problem with doing this in that if
transport_device_add() ever fails it's likely because memory pressure
caused the allocation of the internal_container to fail. What that
means is that the visible sysfs attributes don't get added, but
otherwise the rphy is fully functional as far as the driver sees it, so
this condition doesn't have to be a fatal error which kills the device.
There are two ways of handling this:
1. The above to move the condition from an ignored to a fatal
error.
It's so rare that we almost never see it in practice and if it
ever happened, the machine is so low on memory that something
else is bound to fail an allocation and kill the device anyway,
so treating it as non-fatal likely serves no purpose.
2. Simply to make the assumption that transport_remove_device() is
idempotent true by adding a flag in the internal_class to
signify
removal is required. This would preserve current behaviour and
have the bonus that it only requires a single patch, not one
patch per transport class object that has this problem.
I'd probably prefer 2. since it's way less work, but others might have
different opinions.
Current some callers ignore the return value of
transport_add_device(), if it fails,
it will cause null-ptr-deref in transport_remove_device().
James suggested that add some check in transport_remove_device(), so
all can
be fix in one patch.
Do you have any suggestion for this ?
Personally I prefer 1. However did you develop a prototype patch for
how 2. would look? And how many changes are still required for 1.?
For 1, in total, there are 8 places need be checked
in drivers/scsi/scsi_transport_sas.c, 2 places
in drivers/scsi/scsi_sysfs.c, 3 places
in drivers/scsi/scsi_transport_fc.c, 2 places
in drivers/scsi/scsi_transport_srp.c, 1 place
For 2, I think we can use device_is_registered() to check if add
operation is successful, may be like this (not test yet):
diff --git a/drivers/base/transport_class.c b/drivers/base/transport_class.c
index ccc86206e508..ac41be7b724e 100644
--- a/drivers/base/transport_class.c
+++ b/drivers/base/transport_class.c
@@ -227,9 +227,11 @@ static int transport_remove_classdev(struct
attribute_container *cont,
tclass->remove(tcont, dev, classdev);
if (tclass->remove != anon_transport_dummy_function) {
- if (tcont->statistics)
- sysfs_remove_group(&classdev->kobj, tcont->statistics);
- attribute_container_class_device_del(classdev);
+ if (device_is_registered(classdev)) {
+ if (tcont->statistics)
+ sysfs_remove_group(&classdev->kobj, tcont->statistics);
+ attribute_container_class_device_del(classdev);
+ }
}
return 0;
Thanks,
Yang
Thanks,
John
.
