On Thu, Jun 26, 2025 at 01:19:33PM +0300, Jarkko Sakkinen wrote:
> From: Jarkko Sakkinen <jarkko.sakki...@opinsys.com>
>
> Create a cleanup class for struct tpm_buf using DEFINE_CLASS(), which will
> guarantee that the heap allocated memory will be freed automatically for
> the transient instances of this structure, when they go out of scope.
>
> Wrap this all into help macro CLASS_TPM_BUF().
>
> A TPM buffer can now be declared trivially:
>
> CLASS_TPM_BUF(buf, buf_size);
Right, so learning this while doing and probably DEFINE_CLASS() would be
a bad idea :-) There's a better fit in cleanup.h: DEFINE_FREE() and
__free().
Given thatintroduction of tpm_buf_alloc() wipes out tpm_buf_destroy(),
we don't need to create any new wrappers with DEFINE_FREE() as
linux/slab.h has kfree() covered already.
This leads up to "one step backwards" solution i.e., explicitly call
tpm_buf_alloc() and implictly destroy (null checks are left out from
examples):
struct tpm_buf *buf __free(kfree) = tpm_buf_alloc();
/*
* I dropped buf_size as it will be gone in v3 as requested by
* James earlier.
*/
/* Or: */
struct tpm_buf *buf2 __free(kfree) = NULL;
/* ... */
buf2 = tpm_buf_alloc();
OFF-TOPIC: while doing this patch I noticed maybe 3-5 location where
we have do this:
1. Init something that is more complex to rollback than rolling back
tpm_buf (which is kfree).
2. Init tpm_buf.
3. After this guaranteed success.
Only reason for doing the rollback for the "more complex to rollback
thing" is that stupid placement of tpm_buf_init(). There's no additional
conditionally failing steps after it.
I need to relocate these code blocks and do a reorders as split patches
and place them to the head of the patch set.
This was mostly reminder for myself :-)
BR, Jarkko
