Re: [PATCH 3.12-rc7] KVM: Fix modprobe failure for kvm_intel/kvm_amd

[Paolo Bonzini <pbonzini@redhat.com>]

Il 30/10/2013 16:59, Greg KH ha scritto:
>> > Even if it is okay to exit and not create the files (and I think it's a
>> > bit surprising), I'd like at least a printk to signal what's happening.
>> >  But there should be no reason for debugfs directory creation to fail in
>> > the end, except for basic mistakes such as the one that Tim reported, so
>> > I think it's better to report the failure.
> Creation will "fail" if debugfs is not enabled, so spiting out printk
> messages in that case is not a good idea.

Interestingly, if debugfs is not enabled we are already returning an
error-valued pointer:

static inline struct dentry *debugfs_create_dir(const char *name,
                                                struct dentry *parent)
{
        return ERR_PTR(-ENODEV);
}

which would oops a lot of the current callers.  Very few places use the
currently correct idiom

	if (IS_ERR(root) || !root)

but it's very ugly...  Perhaps debugfs_create_dir *should* return an
error-valued pointer after all.

Paolo