Re: [PATCH v2 2/2] rust: miscdevice: access the `struct miscdevice` from fops->open()

[kernel test robot <lkp@intel.com>]

Hi Alice,

kernel test robot noticed the following build errors:

[auto build test ERROR on 40384c840ea1944d7c5a392e8975ed088ecf0b37]

url:    https://github.com/intel-lab-lkp/linux/commits/Alice-Ryhl/rust-miscdevice-access-file-in-fops/20241209-153054
base:   40384c840ea1944d7c5a392e8975ed088ecf0b37
patch link:    https://lore.kernel.org/r/20241209-miscdevice-file-param-v2-2-83ece27e9ff6%40google.com
patch subject: [PATCH v2 2/2] rust: miscdevice: access the `struct miscdevice` from fops->open()
config: x86_64-rhel-9.4-rust (https://download.01.org/0day-ci/archive/20241209/202412092214.P4acQ6Rn-lkp@intel.com/config)
compiler: clang version 19.1.3 (https://github.com/llvm/llvm-project ab51eccf88f5321e7c60591c5546b254b6afab99)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241209/202412092214.P4acQ6Rn-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202412092214.P4acQ6Rn-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from arch/x86/kernel/asm-offsets.c:14:
   In file included from include/linux/suspend.h:5:
   In file included from include/linux/swap.h:9:
   In file included from include/linux/memcontrol.h:21:
   In file included from include/linux/mm.h:2223:
   include/linux/vmstat.h:504:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
   504 |         return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
   |                            ~~~~~~~~~~~~~~~~~~~~~ ^
   505 |                            item];
   |                            ~~~~
   include/linux/vmstat.h:511:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
   511 |         return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
   |                            ~~~~~~~~~~~~~~~~~~~~~ ^
   512 |                            NR_VM_NUMA_EVENT_ITEMS +
   |                            ~~~~~~~~~~~~~~~~~~~~~~
   include/linux/vmstat.h:518:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
   518 |         return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
   |                               ~~~~~~~~~~~ ^ ~~~
   include/linux/vmstat.h:524:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
   524 |         return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
   |                            ~~~~~~~~~~~~~~~~~~~~~ ^
   525 |                            NR_VM_NUMA_EVENT_ITEMS +
   |                            ~~~~~~~~~~~~~~~~~~~~~~
   4 warnings generated.
   ***
   *** Rust bindings generator 'bindgen' < 0.69.5 together with libclang >= 19.1
   *** may not work due to a bug (https://github.com/rust-lang/rust-bindgen/pull/2824),
   *** unless patched (like Debian's).
   ***   Your bindgen version:  0.65.1
   ***   Your libclang version: 19.1.3
   ***
   ***
   *** Please see Documentation/rust/quick-start.rst for details
   *** on how to set up the Rust support.
   ***
   In file included from rust/helpers/helpers.c:10:
   In file included from rust/helpers/blk.c:3:
   In file included from include/linux/blk-mq.h:5:
   In file included from include/linux/blkdev.h:9:
   In file included from include/linux/blk_types.h:10:
   In file included from include/linux/bvec.h:10:
   In file included from include/linux/highmem.h:8:
   In file included from include/linux/cacheflush.h:5:
   In file included from arch/x86/include/asm/cacheflush.h:5:
   In file included from include/linux/mm.h:2223:
   include/linux/vmstat.h:504:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
   504 |         return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
   |                            ~~~~~~~~~~~~~~~~~~~~~ ^
   505 |                            item];
   |                            ~~~~
   include/linux/vmstat.h:511:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
   511 |         return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
   |                            ~~~~~~~~~~~~~~~~~~~~~ ^
   512 |                            NR_VM_NUMA_EVENT_ITEMS +
   |                            ~~~~~~~~~~~~~~~~~~~~~~
   include/linux/vmstat.h:518:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
   518 |         return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
   |                               ~~~~~~~~~~~ ^ ~~~
   include/linux/vmstat.h:524:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
   524 |         return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
   |                            ~~~~~~~~~~~~~~~~~~~~~ ^
   525 |                            NR_VM_NUMA_EVENT_ITEMS +
   |                            ~~~~~~~~~~~~~~~~~~~~~~
   clang diag: include/linux/vmstat.h:504:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
   clang diag: include/linux/vmstat.h:511:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
   clang diag: include/linux/vmstat.h:518:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
   clang diag: include/linux/vmstat.h:524:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
   4 warnings generated.
   clang diag: include/linux/vmstat.h:504:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
   clang diag: include/linux/vmstat.h:511:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
   clang diag: include/linux/vmstat.h:518:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
   clang diag: include/linux/vmstat.h:524:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
   clang diag: include/linux/vmstat.h:504:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
   clang diag: include/linux/vmstat.h:511:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
   clang diag: include/linux/vmstat.h:518:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
   clang diag: include/linux/vmstat.h:524:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
>> error[E0277]: the size for values of type `Self` cannot be known at compilation time
   --> rust/kernel/miscdevice.rs:107:35
   |
   107 |     fn open(_file: &File, _misc: &MiscDeviceRegistration<Self>) -> Result<Self::Ptr>;
   |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
   |
   note: required by an implicit `Sized` bound in `MiscDeviceRegistration`
   --> rust/kernel/miscdevice.rs:52:35
   |
   52  | pub struct MiscDeviceRegistration<T> {
   |                                   ^ required by the implicit `Sized` requirement on this type parameter in `MiscDeviceRegistration`
   help: consider further restricting `Self`
   |
   107 |     fn open(_file: &File, _misc: &MiscDeviceRegistration<Self>) -> Result<Self::Ptr> where Self: Sized;
   |                                                                                      +++++++++++++++++
   help: consider relaxing the implicit `Sized` restriction
   |
   52  | pub struct MiscDeviceRegistration<T: ?Sized> {
   |                                    ++++++++
--
>> error[E0609]: no field `private_data` on type `File`
   --> rust/kernel/miscdevice.rs:215:22
   |
   215 |     unsafe { (*file).private_data = ptr.into_foreign().cast_mut() };
   |                      ^^^^^^^^^^^^ unknown field

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