[PATCH RFC v2 1/5] nvme: add __always_inline for nvme_pci_npages_prp

[Chen Linxuan <chenlinxuan@uniontech.com>]

From: Winston Wen <wentao@uniontech.com>

On x86_64 with gcc version 13.3.0, I build drivers/nvme/host/pci.c
with:

  make defconfig
  ./scripts/kconfig/merge_config.sh .config <(
    echo CONFIG_BLK_DEV_NVME=m
  )
  make KCFLAGS="-fno-inline-small-functions -fno-inline-functions-called-once" \
    drivers/nvme/host/pci.o

Then I get a compile error:

    CALL    scripts/checksyscalls.sh
    DESCEND objtool
    INSTALL libsubcmd_headers
    CC      drivers/nvme/host/pci.o
  In file included from <command-line>:
  drivers/nvme/host/pci.c: In function 'nvme_init':
  ././include/linux/compiler_types.h:557:45: error: call to '__compiletime_assert_878' declared with attribute error: BUILD_BUG_ON failed: nvme_pci_npages_prp() > NVME_MAX_NR_ALLOCATIONS
    557 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
        |                                             ^
  ././include/linux/compiler_types.h:538:25: note: in definition of macro '__compiletime_assert'
    538 |                         prefix ## suffix();                             \
        |                         ^~~~~~
  ././include/linux/compiler_types.h:557:9: note: in expansion of macro '_compiletime_assert'
    557 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
        |         ^~~~~~~~~~~~~~~~~~~
  ./include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert'
     39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
        |                                     ^~~~~~~~~~~~~~~~~~
  ./include/linux/build_bug.h:50:9: note: in expansion of macro 'BUILD_BUG_ON_MSG'
     50 |         BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
        |         ^~~~~~~~~~~~~~~~
  drivers/nvme/host/pci.c:3804:9: note: in expansion of macro 'BUILD_BUG_ON'
   3804 |         BUILD_BUG_ON(nvme_pci_npages_prp() > NVME_MAX_NR_ALLOCATIONS);
        |         ^~~~~~~~~~~~

Mark nvme_pci_npages_prp() with __always_inline make it can be computed
at compile time.

Co-developed-by: Chen Linxuan <chenlinxuan@uniontech.com>
Signed-off-by: Chen Linxuan <chenlinxuan@uniontech.com>
Signed-off-by: Winston Wen <wentao@uniontech.com>
---
 drivers/nvme/host/pci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index b178d52eac1b7f7286e217226b9b3686d07b7b6c..9ab070a9f0372bc6595c29a884ee9f2ffe5ae8e9 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -390,7 +390,7 @@ static bool nvme_dbbuf_update_and_check_event(u16 value, __le32 *dbbuf_db,
  * as it only leads to a small amount of wasted memory for the lifetime of
  * the I/O.
  */
-static int nvme_pci_npages_prp(void)
+static __always_inline int nvme_pci_npages_prp(void)
 {
 	unsigned max_bytes = (NVME_MAX_KB_SZ * 1024) + NVME_CTRL_PAGE_SIZE;
 	unsigned nprps = DIV_ROUND_UP(max_bytes, NVME_CTRL_PAGE_SIZE);

-- 
2.48.1