With CONFIG_DEBUG_KOBJECT_RELEASE=y, kobject release is delayed even after
the last reference to the object is dropped.
With this turned on, Veaceslav and Zdenek noticed that when we enable,
disable, and re-enable MSIs, we often see errors like "sysfs: cannot create
duplicate filename '/devices/pci0000:00/.../msi_irqs'". This happens
when we unload and reload drivers that use MSI.
The reason is that the MSI disable path uses kset_unregister(dev->msi_kset),
which doesn't remove the kset from sysfs until the the kobject release
function is called. With CONFIG_DEBUG_KOBJECT_RELEASE, the release is
obviously delayed, but even without it, the release will be delayed if
somebody has the kset sysfs file open when kset_unregister() is called.
We could work around this by explicitly calling
"kobject_del(&dev->msi_kset->kobj)", but that seems clunky and other
kset_unregister() users are likely to have similar problems.
The idea of this patch is to make kset_unregister() unlink the kset from
sysfs immediately, before dropping the kset reference.
---
Bjorn Helgaas (2):
kobject: remove kset from sysfs immediately in kset_unregister()
kobject: fix kset sample error path
Documentation/kobject.txt | 3 ++-
lib/kobject.c | 1 +
samples/kobject/kset-example.c | 1 +
3 files changed, 4 insertions(+), 1 deletion(-)
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