[PATCH v2 0/5] treewide: remove unreachable memblock_reserve() return value checks in early boot

[PATCH v2 0/5] treewide: remove unreachable memblock_reserve() return value checks in early boot

[Sang-Heon Jeon]

memblock_reserve() can only return an error after memblock_allow_resize()
has been called. Before that it either succeeds or panics, never returning
an error.

Before memblock_allow_resize() is called, the return value checks of
memblock_reserve() are unreachable and can be removed.

All the call sites are in different trees, so I split the change into one
patch per arch/subsystem. The patches are independent and can be applied
separately.

---
Changes from v1 [1]
- add reviewed-by tag
- rebased onto latest memblock for-next

[1] https://lore.kernel.org/all/20260616182959.2429774-1-ekffu200098@gmail.com/
---
Hello Mike,

Like the previous memblock cleanup series, could you review and take this patch series to the memblock tree?

Thank you for taking valuable time.

Best Regards,
Sang-Heon Jeon
---

Sang-Heon Jeon (5):
  x86/setup: remove unreachable memblock_reserve() return value check
  sh: remove unreachable memblock_reserve() return value check
  powerpc/fadump: remove unreachable memblock_reserve() return value
    checks
  xtensa: remove unreachable memblock_reserve() return value checks
  Revert "tpm: do not ignore memblock_reserve return value"

 arch/powerpc/kernel/fadump.c   | 14 +++-----------
 arch/sh/kernel/machine_kexec.c |  7 +------
 arch/x86/kernel/setup.c        |  7 ++-----
 arch/xtensa/kernel/setup.c     | 13 +++++++------
 drivers/firmware/efi/tpm.c     |  7 +------
 5 files changed, 14 insertions(+), 34 deletions(-)

-- 
2.43.0

[PATCH v2 5/5] Revert "tpm: do not ignore memblock_reserve return value"

[Sang-Heon Jeon]

This reverts commit c33c28f9f6e017702374e1ab907dfa5a63db5301.

efi_tpm_eventlog_init() runs from efi_config_parse_tables() during early
EFI initialization, before memblock_allow_resize(). At that point
memblock_reserve() either succeeds or panics, never returning an error.

Therefore the return value check is unreachable, so restore the original
unconditional memblock_reserve().

No functional change.

Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
---
 drivers/firmware/efi/tpm.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/firmware/efi/tpm.c b/drivers/firmware/efi/tpm.c
index cdd431027065..288bcf7a5b99 100644
--- a/drivers/firmware/efi/tpm.c
+++ b/drivers/firmware/efi/tpm.c
@@ -61,12 +61,7 @@ int __init efi_tpm_eventlog_init(void)
 	}
 
 	tbl_size = sizeof(*log_tbl) + log_tbl->size;
-	if (memblock_reserve(efi.tpm_log, tbl_size)) {
-		pr_err("TPM Event Log memblock reserve fails (0x%lx, 0x%x)\n",
-		       efi.tpm_log, tbl_size);
-		ret = -ENOMEM;
-		goto out;
-	}
+	memblock_reserve(efi.tpm_log, tbl_size);
 
 	if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR) {
 		pr_info("TPM Final Events table not present\n");
-- 
2.43.0

Re: [PATCH v2 0/5] treewide: remove unreachable memblock_reserve() return value checks in early boot

[Mike Rapoport]

Hi Sang-Heon,

On Tue, Jul 07, 2026 at 01:37:48AM +0900, Sang-Heon Jeon wrote:
> memblock_reserve() can only return an error after memblock_allow_resize()
> has been called. Before that it either succeeds or panics, never returning
> an error.
> 
> Before memblock_allow_resize() is called, the return value checks of
> memblock_reserve() are unreachable and can be removed.

I'd rather keep these checks.

Removing them relies on internal details of memblock_reserve() implementation
and the existing event sequence. If the code would move around relying on
panic in memblock_reserve() may not be correct.

And the few bytes and cycles the change saves do not worth the churn.

-- 
Sincerely yours,
Mike.