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[RFC,v2,3/5] vfio/virtio: add __always_inline for virtiovf_get_device_config_size

Message ID 20250416-noautoinline-v2-3-e69a2717530f@uniontech.com (mailing list archive)
State New
Headers show
Series kernel-hacking: introduce CONFIG_NO_AUTO_INLINE | expand

Commit Message

Chen Linxuan April 16, 2025, 9:44 a.m. UTC 
From: Winston Wen <wentao@uniontech.com>

Presume that kernel is compiled for x86_64 with gcc version 13.3.0:

  make defconfig
  ./scripts/kconfig/merge_config.sh .config <(
    echo CONFIG_VFIO=m
    echo CONFIG_VIRTIO_PCI=y
    echo CONFIG_VIRTIO_PCI_LIB_LEGACY=y
    echo CONFIG_VIRTIO_VFIO_PCI=m
    echo CONFIG_VIRTIO_VFIO_PCI_ADMIN_LEGACY=y
  )
  make KCFLAGS="-fno-inline-small-functions -fno-inline-functions-called-once" \
    drivers/vfio/pci/virtio/legacy_io.o

This results a compile error:

    CALL    scripts/checksyscalls.sh
    DESCEND objtool
    INSTALL libsubcmd_headers
    CC      drivers/vfio/pci/virtio/legacy_io.o
  In file included from <command-line>:
  drivers/vfio/pci/virtio/legacy_io.c: In function 'virtiovf_init_legacy_io':
  ././include/linux/compiler_types.h:557:45: error: call to '__compiletime_assert_889' declared with attribute error: BUILD_BUG_ON failed: !is_power_of_2(virtvdev->bar0_virtual_buf_size)
    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/vfio/pci/virtio/legacy_io.c:401:9: note: in expansion of macro 'BUILD_BUG_ON'
    401 |         BUILD_BUG_ON(!is_power_of_2(virtvdev->bar0_virtual_buf_size));
        |         ^~~~~~~~~~~~

BUILD_BUG_ON needs virtvdev->bar0_virtual_buf_size to be computed at
compile time. So we should mark virtiovf_get_device_config_size() with
__always_inline here.

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/vfio/pci/virtio/legacy_io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/vfio/pci/virtio/legacy_io.c b/drivers/vfio/pci/virtio/legacy_io.c
index 832af5ba267c49a079009cfe0fa93c15ba7a490f..b6871d50b9f9e278ef3c49a9cb2baf474b8271c6 100644
--- a/drivers/vfio/pci/virtio/legacy_io.c
+++ b/drivers/vfio/pci/virtio/legacy_io.c
@@ -350,7 +350,7 @@  int virtiovf_open_legacy_io(struct virtiovf_pci_core_device *virtvdev)
 	return virtiovf_set_notify_addr(virtvdev);
 }
 
-static int virtiovf_get_device_config_size(unsigned short device)
+static __always_inline int virtiovf_get_device_config_size(unsigned short device)
 {
 	/* Network card */
 	return offsetofend(struct virtio_net_config, status);