On 9/26/19 4:29 PM, Ard Biesheuvel wrote:
On Thu, 26 Sep 2019 at 16:12, Ross Lagerwall <ross.lagerwall@xxxxxxxxxx> wrote:
If a backend does not implement non-blocking EFI operations, it implies
that the normal operations are non-blocking.
Is that documented anywhere?
Sort of. From commit 6d80dba1c9fe "efi: Provide a non-blocking
SetVariable() operation"
"""
Introduce ->set_variable_nonblocking() for this use case. It is an
optional EFI backend operation, and need only be implemented by those
backends that usually acquire locks to serialize access to EFI
variables, as is the case for virt_efi_set_variable() where we now grab
the EFI runtime spinlock.
"""
Instead of crashing
dereferencing a NULL pointer, fallback to the normal operations since it
is safe to do so.
I agree that crashing is never the right thing to do, but I wonder
whether we shouldn't just bail instead. If the provided default
operation is non-blocking, the platform can populate the function
pointer with a reference to the default implementation.
If you would prefer it that platforms are always required to implement
the non-blocking functions, then I will just send a simple patch fixing
up the Xen implementation.
Thanks,
--
Ross Lagerwall
