Note: cc'ing the code's author.
Marc-André Lureau <marcandre.lur...@redhat.com> writes:
> Make be_drivers[n] match order of TpmType enum.
>
> Use qapi_enum_parse() in tpm_get_backend_driver.
>
> Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
> ---
> include/sysemu/tpm_backend.h | 2 +-
> tpm.c | 42 ++++++++++++------------------------------
> 2 files changed, 13 insertions(+), 31 deletions(-)
Before the patch, we have a strict separation between enum TpmModel /
tpm_models[] and enum TpmType / be_drivers[]:
* TpmModel may have any number of members. It just happens to have one.
* Same for TpmType.
* tpm_models[] may have any number of elements. It just happens to have
the same number of elements as TpmModel has members.
If it had more, they'd be wasted: tpm_register_model() can't use more
than one per TpmModel member. If it had fewer, tpm_register_model()
could fail. Its caller ignores failure.
* be_drivers[] is different: tpm_register_driver() happily adds drivers
as long as be_drivers[] has space. Its caller ignores failure.
If you register more than one with a given TpmType,
tpm_driver_find_by_type(), tpm_get_backend_driver() will find only the
one one that registered first. tpm_display_backend_drivers() happily
shows all of them.
* The order of TpmModel members and tpm_models[] elements is
independent. The former is fixed in the QAPI schema, the latter is
determined by registration order, which is unspecified.
Corollary: using a TpmModel to subscript tpm_models[] is wrong.
* Same for TpmType and be_drivers[]: using a TpmType to subscript
be_drivers[] is wrong.
Hard to tell whether this is / has become more a case of overengineering
or more a case of under-make-sense-ing.
> diff --git a/include/sysemu/tpm_backend.h b/include/sysemu/tpm_backend.h
> index b58f52d39f..1d21c6b19b 100644
> --- a/include/sysemu/tpm_backend.h
> +++ b/include/sysemu/tpm_backend.h
> @@ -227,6 +227,6 @@ TPMBackend *qemu_find_tpm(const char *id);
>
> const TPMDriverOps *tpm_get_backend_driver(const char *type);
> int tpm_register_model(enum TpmModel model);
> -int tpm_register_driver(const TPMDriverOps *tdo);
> +void tpm_register_driver(const TPMDriverOps *tdo);
>
> #endif
> diff --git a/tpm.c b/tpm.c
> index c3b731b3f2..f175661bfe 100644
> --- a/tpm.c
> +++ b/tpm.c
> @@ -26,9 +26,8 @@ static QLIST_HEAD(, TPMBackend) tpm_backends =
>
>
> #define TPM_MAX_MODELS 1
> -#define TPM_MAX_DRIVERS 1
>
> -static TPMDriverOps const *be_drivers[TPM_MAX_DRIVERS] = {
> +static TPMDriverOps const *be_drivers[TPM_TYPE__MAX] = {
> NULL,
> };
>
> @@ -64,31 +63,18 @@ static bool tpm_model_is_registered(enum TpmModel model)
>
> const TPMDriverOps *tpm_get_backend_driver(const char *type)
> {
> - int i;
> + int i = qapi_enum_parse(TpmType_lookup, type, TPM_TYPE__MAX, -1, NULL);
>
> - for (i = 0; i < TPM_MAX_DRIVERS && be_drivers[i] != NULL; i++) {
> - if (!strcmp(TpmType_lookup[be_drivers[i]->type], type)) {
> - return be_drivers[i];
> - }
> - }
> -
> - return NULL;
> + return i >= 0 ? be_drivers[i] : NULL;
> }
>
> #ifdef CONFIG_TPM
>
> -int tpm_register_driver(const TPMDriverOps *tdo)
> +void tpm_register_driver(const TPMDriverOps *tdo)
> {
> - int i;
> + assert(!be_drivers[tdo->type]);
>
> - for (i = 0; i < TPM_MAX_DRIVERS; i++) {
> - if (!be_drivers[i]) {
> - be_drivers[i] = tdo;
> - return 0;
> - }
> - }
> - error_report("Could not register TPM driver");
> - return 1;
> + be_drivers[tdo->type] = tdo;
> }
>
> /*
> @@ -101,9 +87,12 @@ static void tpm_display_backend_drivers(void)
>
> fprintf(stderr, "Supported TPM types (choose only one):\n");
>
> - for (i = 0; i < TPM_MAX_DRIVERS && be_drivers[i] != NULL; i++) {
> + for (i = 0; i < TPM_TYPE__MAX; i++) {
> + if (be_drivers[i] == NULL) {
> + continue;
> + }
> fprintf(stderr, "%12s %s\n",
> - qapi_enum_lookup(TpmType_lookup, be_drivers[i]->type),
> + qapi_enum_lookup(TpmType_lookup, i),
> be_drivers[i]->desc());
> }
> fprintf(stderr, "\n");
> @@ -241,14 +230,7 @@ int tpm_config_parse(QemuOptsList *opts_list, const char
> *optarg)
>
> static const TPMDriverOps *tpm_driver_find_by_type(enum TpmType type)
> {
> - int i;
> -
> - for (i = 0; i < TPM_MAX_DRIVERS && be_drivers[i] != NULL; i++) {
> - if (be_drivers[i]->type == type) {
> - return be_drivers[i];
> - }
> - }
> - return NULL;
> + return be_drivers[type];
> }
>
> static TPMInfo *qmp_query_tpm_inst(TPMBackend *drv)
You kill the separation of TpmType and be_drivers[]: TpmType values
become valid subscripts of be_drivers[]. Good!
You don't touch TpmModel and tpm_models[]. Half of the mess remains in
place to confuse the next reader (it certainly confused me, thus the
long "before the patch" treatise). Not wrong, therefore
Reviewed-by: Markus Armbruster <arm...@redhat.com>
but could you complete the cleanup job? Pretty-please?
Also: since I wrote the "before the patch" treatise already, could (some
of) it be worked into the commit message?
