[BUG REPORT] use of unreachable() masks uninitialized variables warnings

[Jeff Merkey]

Hi,

I noticed that the use of the function -- unreachable() -- inside of
the BUG() macro in arch/x86/include/asm/bug.h causes compiler output
to be suspect based on review of assembly output for quite a few
areas.

if as a test, you remove the call to unreachable() in the BUG() macro,
it seems to generate a large number of build warnings about the use of
uninitialized variables that are apparently masked by the compiler
since it believes this code is going to halt, even in the cases where
the BUG() macro is used conditionally, as in an if (condition) then
BUG() (which the compiler does not seem to understand).

This seems to indicate that the use of these built in macros telling
the compiler to create a bunch of infinite jump labels is masking
quite a few bugs lurking around in the regular code since gcc
apparently just throws out the checks for uninitialized variables in
any function if it sees this macro anywhere in the function.

Here are the sources of several bugs I have seen recently in ext4 I am
pretty sure with a null bh.  One good check is to set the BUG() macro
NOT TO call unreachable() as a build test since the compiler will
ignore uninitialized variables in a function if someone calls BUG()
even conditionally, and never report them during build.


The following are from v4.4.1 with a BUG() macro with the call to
unreachable() removed:

arch/x86/kernel/apic/x2apic_uv_x.c: In function âboot_pnode_to_bladeâ:
arch/x86/kernel/apic/x2apic_uv_x.c:443:1: warning: control reaches end
of non-void function [-Wreturn-type]
 }
 ^
arch/x86/kernel/apic/x2apic_uv_x.c: In function âuv_acpi_madt_oem_checkâ:
arch/x86/kernel/apic/x2apic_uv_x.c:201:1: warning: control reaches end
of non-void function [-Wreturn-type]
 }
 ^
arch/x86/kvm/x86.c: In function âemulator_cmpxchg_emulatedâ:
arch/x86/kvm/x86.c:4562:5: warning: âexchangedâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
  if (!exchanged)
     ^
In file included from kernel/locking/qspinlock.c:470:0:
kernel/locking/qspinlock_paravirt.h: In function âpv_unhashâ:
kernel/locking/qspinlock_paravirt.h:144:1: warning: control reaches
end of non-void function [-Wreturn-type]
 }
 ^
kernel/locking/qspinlock_paravirt.h: In function âpv_hashâ:
kernel/locking/qspinlock_paravirt.h:121:1: warning: control reaches
end of non-void function [-Wreturn-type]
 }
 ^
kernel/sched/core.c: In function âpick_next_taskâ:
kernel/sched/core.c:3064:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
kernel/seccomp.c: In function âseccomp_phase1â:
kernel/seccomp.c:672:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
mm/mmap.c: In function âvma_adjustâ:
mm/mmap.c:661:15: warning: ârb_parentâ may be used uninitialized in
this function [-Wmaybe-uninitialized]
  __vma_link_rb(mm, vma, rb_link, rb_parent);
               ^
mm/mmap.c:692:29: note: ârb_parentâ was declared here
  struct rb_node **rb_link, *rb_parent;
                             ^
mm/mmap.c:661:15: warning: ârb_linkâ may be used uninitialized in this
function [-Wmaybe-uninitialized]
  __vma_link_rb(mm, vma, rb_link, rb_parent);
               ^
mm/mmap.c:692:19: note: ârb_linkâ was declared here
  struct rb_node **rb_link, *rb_parent;
                   ^
mm/mmap.c:660:17: warning: âprevâ may be used uninitialized in this
function [-Wmaybe-uninitialized]
  __vma_link_list(mm, vma, prev, rb_parent);
                 ^
mm/mmap.c:691:25: note: âprevâ was declared here
  struct vm_area_struct *prev;
                         ^
mm/hugetlb.c: In function â__vma_reservation_commonâ:
mm/hugetlb.c:1815:3: warning: âretâ may be used uninitialized in this
function [-Wmaybe-uninitialized]
   return ret < 0 ? ret : 0;
   ^
mm/mempolicy.c: In function âmempolicy_slab_nodeâ:
mm/mempolicy.c:1731:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
mm/memcontrol.c: In function âmem_cgroup_read_u64â:
mm/memcontrol.c:2892:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
In file included from mm/memcontrol.c:34:0:
mm/memcontrol.c: In function âmem_cgroup_resetâ:
include/linux/page_counter.h:49:21: warning: âcounterâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
  counter->watermark = page_counter_read(counter);
                     ^
mm/memcontrol.c:3038:23: note: âcounterâ was declared here
  struct page_counter *counter;
                       ^
mm/memcontrol.c: In function â__mem_cgroup_usage_unregister_eventâ:
mm/memcontrol.c:3511:6: warning: âusageâ may be used uninitialized in
this function [-Wmaybe-uninitialized]
   if (new->entries[j].threshold <= usage) {
      ^
mm/memcontrol.c:3506:35: warning: âthresholdsâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
  for (i = 0, j = 0; i < thresholds->primary->size; i++) {
                                   ^
mm/memcontrol.c: In function â__mem_cgroup_usage_register_eventâ:
mm/memcontrol.c:3423:6: warning: âusageâ may be used uninitialized in
this function [-Wmaybe-uninitialized]
   if (new->entries[i].threshold <= usage) {
      ^
mm/memcontrol.c:3392:16: warning: âthresholdsâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
  if (thresholds->primary)
                ^
In file included from ./arch/x86/include/asm/atomic.h:4:0,
                 from include/linux/atomic.h:4,
                 from include/linux/page_counter.h:4,
                 from mm/memcontrol.c:34:
mm/memcontrol.c: In function âmem_cgroup_read_u64â:
include/linux/compiler.h:207:26: warning: âcounterâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
  case 8: *(__u64 *)res = *(volatile __u64 *)p; break;  \
                          ^
mm/memcontrol.c:2858:23: note: âcounterâ was declared here
  struct page_counter *counter;
                       ^
mm/hugetlb_cgroup.c: In function âhugetlb_cgroup_read_u64â:
mm/hugetlb_cgroup.c:268:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
fs/btrfs/inode.c: In function ârun_delalloc_nocowâ:
fs/btrfs/inode.c:1384:6: warning: âextent_endâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
   if (extent_end <= start) {
      ^
In file included from include/linux/sched.h:17:0,
                 from fs/btrfs/volumes.c:18:
fs/btrfs/volumes.c: In function â__btrfs_alloc_chunkâ:
include/linux/kernel.h:725:24: warning: âmax_chunk_sizeâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
  _min1 < _min2 ? _min1 : _min2; })
                        ^
fs/btrfs/volumes.c:4507:6: note: âmax_chunk_sizeâ was declared here
  u64 max_chunk_size;
      ^
fs/btrfs/volumes.c:4599:29: warning: âmax_stripe_sizeâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
   ret = find_free_dev_extent(trans, device,
                             ^
fs/btrfs/delayed-inode.c: In function â__btrfs_add_delayed_itemâ:
fs/btrfs/delayed-inode.c:407:18: warning: ârootâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
  struct rb_root *root;
                  ^
fs/btrfs/backref.c: In function â__add_delayed_refsâ:
fs/btrfs/backref.c:649:33: warning: âsgnâ may be used uninitialized in
this function [-Wmaybe-uninitialized]
   *total_refs += (node->ref_mod * sgn);
                                 ^
fs/btrfs/acl.c: In function âbtrfs_get_aclâ:
fs/btrfs/acl.c:49:25: warning: ânameâ may be used uninitialized in
this function [-Wmaybe-uninitialized]
  size = __btrfs_getxattr(inode, name, "", 0);
                         ^
fs/ceph/locks.c: In function âceph_lock_wait_for_completionâ:
fs/ceph/locks.c:140:40: warning: âlock_typeâ may be used uninitialized
in this function [-Wmaybe-uninitialized]
  intr_req->r_args.filelock_change.rule = lock_type;
                                        ^
In file included from fs/ext4/file.c:30:0:
fs/ext4/ext4_jbd2.h: In function âext4_inode_journal_modeâ:
fs/ext4/ext4_jbd2.h:409:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
In file included from fs/ext4/fsync.c:32:0:
fs/ext4/ext4_jbd2.h: In function âext4_inode_journal_modeâ:
fs/ext4/ext4_jbd2.h:409:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
In file included from fs/ext4/inode.c:41:0:
fs/ext4/ext4_jbd2.h: In function âext4_inode_journal_modeâ:
fs/ext4/ext4_jbd2.h:409:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
fs/ext4/inode.c: In function âext4_map_blocksâ:
fs/ext4/inode.c:548:5: warning: âretvalâ may be used uninitialized in
this function [-Wmaybe-uninitialized]
  if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
     ^
In file included from fs/ext4/super.c:48:0:
fs/ext4/ext4_jbd2.h: In function âext4_inode_journal_modeâ:
fs/ext4/ext4_jbd2.h:409:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
In file included from fs/ext4/extents.c:43:0:
fs/ext4/ext4_jbd2.h: In function âext4_inode_journal_modeâ:
fs/ext4/ext4_jbd2.h:409:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
fs/ext4/extents.c: In function âext4_ext_put_gap_in_cacheâ:
fs/ext4/extents.c:2306:14: warning: âlblockâ may be used uninitialized
in this function [-Wmaybe-uninitialized]
  ext4_lblk_t lblock;
              ^
fs/ext4/extents.c:2305:14: warning: âlenâ may be used uninitialized in
this function [-Wmaybe-uninitialized]
  ext4_lblk_t len;
              ^
In file included from fs/ext4/ext4_jbd2.c:5:0:
fs/ext4/ext4_jbd2.h: In function âext4_inode_journal_modeâ:
fs/ext4/ext4_jbd2.h:409:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
In file included from fs/ext4/mballoc.c:24:0:
fs/ext4/ext4_jbd2.h: In function âext4_inode_journal_modeâ:
fs/ext4/ext4_jbd2.h:409:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
In file included from fs/ext4/move_extent.c:19:0:
fs/ext4/ext4_jbd2.h: In function âext4_inode_journal_modeâ:
fs/ext4/ext4_jbd2.h:409:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
In file included from fs/ext4/indirect.c:23:0:
fs/ext4/ext4_jbd2.h: In function âext4_inode_journal_modeâ:
fs/ext4/ext4_jbd2.h:409:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
In file included from fs/ext4/inline.c:17:0:
fs/ext4/ext4_jbd2.h: In function âext4_inode_journal_modeâ:
fs/ext4/ext4_jbd2.h:409:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
fs/ext4/acl.c: In function âext4_get_aclâ:
fs/ext4/acl.c:160:9: warning: âname_indexâ may be used uninitialized
in this function [-Wmaybe-uninitialized]
  retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
         ^
fs/nfs/filelayout/filelayout.c: In function âfilelayout_get_dserver_offsetâ:
fs/nfs/filelayout/filelayout.c:86:1: warning: control reaches end of
non-void function [-Wreturn-type]
 }
 ^
fs/nfs/flexfilelayout/flexfilelayoutdev.c: In function
ânfs4_ff_find_or_create_ds_clientâ:
fs/nfs/flexfilelayout/flexfilelayoutdev.c:493:1: warning: control
reaches end of non-void function [-Wreturn-type]
 }
 ^
In file included from include/linux/sunrpc/svcsock.h:13:0,
                 from include/linux/sunrpc/svcauth_gss.h:16,
                 from fs/nfsd/nfs4state.c:42:
include/linux/sunrpc/svc_xprt.h: In function âsvc_addr_lenâ:
include/linux/sunrpc/svc_xprt.h:174:1: warning: control reaches end of
non-void function [-Wreturn-type]
 }
 ^
fs/notify/fanotify/fanotify.c: In function âfanotify_handle_eventâ:
fs/notify/fanotify/fanotify.c:143:32: warning: âmarks_ignored_maskâ
may be used uninitialized in this function [-Wmaybe-uninitialized]
      !(marks_mask & FS_ISDIR & ~marks_ignored_mask))
                                ^
fs/notify/fanotify/fanotify.c:106:20: note: âmarks_ignored_maskâ was
declared here
  __u32 marks_mask, marks_ignored_mask;
                    ^
fs/notify/fanotify/fanotify.c:143:30: warning: âmarks_maskâ may be
used uninitialized in this function [-Wmaybe-uninitialized]
      !(marks_mask & FS_ISDIR & ~marks_ignored_mask))
                              ^
fs/notify/fanotify/fanotify.c:106:8: note: âmarks_maskâ was declared here
  __u32 marks_mask, marks_ignored_mask;
        ^
fs/quota/kqid.c: In function âqid_eqâ:
fs/quota/kqid.c:26:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
fs/quota/kqid.c: In function âqid_ltâ:
fs/quota/kqid.c:52:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
fs/quota/kqid.c: In function âfrom_kqidâ:
fs/quota/kqid.c:79:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
fs/quota/kqid.c: In function âfrom_kqid_mungedâ:
fs/quota/kqid.c:112:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
fs/quota/kqid.c: In function âqid_validâ:
fs/quota/kqid.c:131:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
fs/udf/inode.c: In function âudf_setsizeâ:
fs/udf/inode.c:641:15: warning: âadsizeâ may be used uninitialized in
this function [-Wmaybe-uninitialized]
   epos.offset -= adsize;
               ^
fs/udf/inode.c:608:6: note: âadsizeâ was declared here
  int adsize;
      ^
fs/udf/truncate.c: In function âudf_truncate_tail_extentâ:
fs/udf/truncate.c:105:16: warning: âadsizeâ may be used uninitialized
in this function [-Wmaybe-uninitialized]
    epos.offset -= adsize;
                ^
fs/udf/truncate.c: In function âudf_truncate_extentsâ:
fs/udf/truncate.c:229:14: warning: âadsizeâ may be used uninitialized
in this function [-Wmaybe-uninitialized]
  epos.offset -= adsize;
              ^
fs/xfs/xfs_acl.c: In function âxfs_get_aclâ:
fs/xfs/xfs_acl.c:156:8: warning: âea_nameâ may be used uninitialized
in this function [-Wmaybe-uninitialized]
  error = xfs_attr_get(ip, ea_name, (unsigned char *)xfs_acl,
        ^
fs/posix_acl.c: In function âacl_by_typeâ:
fs/posix_acl.c:34:1: warning: control reaches end of non-void function
[-Wreturn-type]
 }
 ^
In file included from include/linux/async_tx.h:20:0,
                 from crypto/async_tx/async_pq.c:27:
include/linux/dmaengine.h: In function âdma_maxpqâ:
include/linux/dmaengine.h:955:1: warning: control reaches end of
non-void function [-Wreturn-type]
 }
 ^
block/cfq-iosched.c: In function âcfq_async_queue_prioâ:
block/cfq-iosched.c:3775:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
drivers/ata/pata_atiixp.c: In function âatiixp_set_dmamodeâ:
drivers/ata/pata_atiixp.c:195:24: warning: âwanted_pioâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
   atiixp_set_pio_timing(ap, adev, wanted_pio);
                        ^
drivers/gpu/drm/gma500/psb_irq.c: In function âpsb_pipestatâ:
drivers/gpu/drm/gma500/psb_irq.c:47:1: warning: control reaches end of
non-void function [-Wreturn-type]
 }
 ^
drivers/gpu/drm/gma500/psb_irq.c: In function âmid_pipe_eventâ:
drivers/gpu/drm/gma500/psb_irq.c:59:1: warning: control reaches end of
non-void function [-Wreturn-type]
 }
 ^
drivers/gpu/drm/gma500/psb_irq.c: In function âmid_pipeconfâ:
drivers/gpu/drm/gma500/psb_irq.c:83:1: warning: control reaches end of
non-void function [-Wreturn-type]
 }
 ^
drivers/gpu/drm/i915/i915_sysfs.c: In function âgt_rp_mhz_showâ:
drivers/gpu/drm/i915/i915_sysfs.c:492:17: warning: âvalâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
  return snprintf(buf, PAGE_SIZE, "%d\n", val);
                 ^
In file included from drivers/gpu/drm/i915/i915_trace.h:10:0,
                 from drivers/gpu/drm/i915/i915_drv.h:2636,
                 from drivers/gpu/drm/i915/intel_runtime_pm.c:32:
drivers/gpu/drm/i915/intel_drv.h: In function âvlv_dport_to_phyâ:
drivers/gpu/drm/i915/intel_drv.h:837:1: warning: control reaches end
of non-void function [-Wreturn-type]
 }
 ^
drivers/gpu/drm/i915/intel_drv.h: In function âvlv_dport_to_channelâ:
drivers/gpu/drm/i915/intel_drv.h:823:1: warning: control reaches end
of non-void function [-Wreturn-type]
 }
 ^
drivers/gpu/drm/i915/i915_cmd_parser.c: In function âi915_cmd_parser_init_ringâ:
drivers/gpu/drm/i915/i915_cmd_parser.c:563:2: warning:
âcmd_table_countâ may be used uninitialized in this function
[-Wmaybe-uninitialized]
  for (i = 0; i < cmd_table_count; i++) {
  ^
drivers/gpu/drm/i915/i915_cmd_parser.c:691:6: note: âcmd_table_countâ
was declared here
  int cmd_table_count;
      ^
drivers/gpu/drm/i915/i915_cmd_parser.c:690:35: warning: âcmd_tablesâ
may be used uninitialized in this function [-Wmaybe-uninitialized]
  const struct drm_i915_cmd_table *cmd_tables;
                                   ^
In file included from include/linux/list.h:8:0,
                 from include/linux/agp_backend.h:33,
                 from include/drm/drmP.h:35,
                 from drivers/gpu/drm/i915/i915_gem_context.c:88:
drivers/gpu/drm/i915/i915_gem_context.c: In function âi915_gem_context_initâ:
include/linux/kernel.h:63:30: warning: âretâ may be used uninitialized
in this function [-Wmaybe-uninitialized]
 #define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
                              ^
drivers/gpu/drm/i915/i915_gem_context.c:111:6: note: âretâ was declared here
  int ret;
      ^
In file included from drivers/gpu/drm/i915/intel_display.c:36:0:
drivers/gpu/drm/i915/intel_drv.h: In function âvlv_pipe_to_channelâ:
drivers/gpu/drm/i915/intel_drv.h:851:1: warning: control reaches end
of non-void function [-Wreturn-type]
 }
 ^
drivers/gpu/drm/i915/intel_display.c: In function âironlake_check_fdi_lanesâ:
drivers/gpu/drm/i915/intel_display.c:6564:1: warning: control reaches
end of non-void function [-Wreturn-type]
 }
 ^
drivers/gpu/drm/i915/intel_display.c: In function âvlv_wait_port_readyâ:
drivers/gpu/drm/i915/intel_display.c:1841:6: warning: âdpll_regâ may
be used uninitialized in this function [-Wmaybe-uninitialized]
  int dpll_reg;
      ^
drivers/gpu/drm/i915/intel_display.c:1861:36: warning: âport_maskâ may
be used uninitialized in this function [-Wmaybe-uninitialized]
  if (wait_for((I915_READ(dpll_reg) & port_mask) == expected_mask, 1000))
                                    ^
drivers/gpu/drm/i915/intel_ddi.c: In function âintel_prepare_ddiâ:
drivers/gpu/drm/i915/intel_ddi.c:441:30: warning: âddi_translationsâ
may be used uninitialized in this function [-Wmaybe-uninitialized]
  const struct ddi_buf_trans *ddi_translations;
                              ^
drivers/gpu/drm/i915/intel_ddi.c:435:6: warning: âsizeâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
      size;
      ^
In file included from drivers/gpu/drm/i915/intel_dp.c:38:0:
drivers/gpu/drm/i915/intel_drv.h: In function âvlv_pipe_to_channelâ:
drivers/gpu/drm/i915/intel_drv.h:851:1: warning: control reaches end
of non-void function [-Wreturn-type]
 }
 ^
drivers/gpu/drm/i915/intel_drv.h: In function âvlv_dport_to_channelâ:
drivers/gpu/drm/i915/intel_drv.h:823:1: warning: control reaches end
of non-void function [-Wreturn-type]
 }
 ^
In file included from drivers/gpu/drm/i915/intel_hdmi.c:37:0:
drivers/gpu/drm/i915/intel_drv.h: In function âvlv_dport_to_channelâ:
drivers/gpu/drm/i915/intel_drv.h:823:1: warning: control reaches end
of non-void function [-Wreturn-type]
 }
 ^
drivers/gpu/drm/nouveau/nvkm/subdev/clk/nv50.c: In function âread_pll_refâ:
drivers/gpu/drm/nouveau/nvkm/subdev/clk/nv50.c:118:5: warning: âMâ may
be used uninitialized in this function [-Wmaybe-uninitialized]
  if (M)
     ^
drivers/gpu/drm/nouveau/nvkm/subdev/clk/nv50.c:58:12: note: âMâ was
declared here
  int P, N, M, id;
            ^
drivers/gpu/drm/nouveau/nvkm/subdev/clk/nv50.c:119:15: warning: âNâ
may be used uninitialized in this function [-Wmaybe-uninitialized]
   return (ref * N / M) >> P;
               ^
drivers/gpu/drm/nouveau/nvkm/subdev/clk/nv50.c:58:9: note: âNâ was declared here
  int P, N, M, id;
         ^
drivers/gpu/drm/nouveau/nvkm/subdev/clk/nv50.c:119:3: warning: âPâ may
be used uninitialized in this function [-Wmaybe-uninitialized]
   return (ref * N / M) >> P;
   ^
drivers/gpu/drm/nouveau/nvkm/subdev/clk/nv50.c:58:6: note: âPâ was declared here
  int P, N, M, id;
      ^
drivers/gpu/drm/radeon/ni.c: In function âni_init_microcodeâ:
drivers/gpu/drm/radeon/ni.c:812:6: warning: âmc_req_sizeâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
   if (rdev->mc_fw->size != mc_req_size) {
      ^
drivers/gpu/drm/radeon/ni.c:799:5: warning: ârlc_req_sizeâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
  if (rdev->rlc_fw->size != rlc_req_size) {
     ^
drivers/gpu/drm/radeon/ni.c:788:5: warning: âme_req_sizeâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
  if (rdev->me_fw->size != me_req_size) {
     ^
drivers/gpu/drm/radeon/ni.c:776:5: warning: âpfp_req_sizeâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
  if (rdev->pfp_fw->size != pfp_req_size) {
     ^
drivers/gpu/drm/radeon/ni.c:795:10: warning: ârlc_chip_nameâ may be
used uninitialized in this function [-Wmaybe-uninitialized]
  snprintf(fw_name, sizeof(fw_name), "radeon/%s_rlc.bin", rlc_chip_name);
          ^
drivers/gpu/drm/radeon/ni.c:821:11: warning: âchip_nameâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
   snprintf(fw_name, sizeof(fw_name), "radeon/%s_smc.bin", chip_name);
           ^
drivers/gpu/drm/radeon/si.c: In function âsi_initâ:
drivers/gpu/drm/radeon/si.c:1830:42: warning: âmc2_req_sizeâ may be
used uninitialized in this function [-Wmaybe-uninitialized]
   if ((rdev->mc_fw->size != mc_req_size) &&
                                          ^
drivers/gpu/drm/radeon/si.c:1652:23: note: âmc2_req_sizeâ was declared here
  size_t smc_req_size, mc2_req_size;
                       ^
drivers/gpu/drm/radeon/si.c:1862:13: warning: âsmc_req_sizeâ may be
used uninitialized in this function [-Wmaybe-uninitialized]
   } else if (rdev->smc_fw->size != smc_req_size) {
             ^
drivers/gpu/drm/radeon/si.c:1652:9: note: âsmc_req_sizeâ was declared here
  size_t smc_req_size, mc2_req_size;
         ^
drivers/gpu/drm/radeon/si.c:1830:6: warning: âmc_req_sizeâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
   if ((rdev->mc_fw->size != mc_req_size) &&
      ^
drivers/gpu/drm/radeon/si.c:1651:63: note: âmc_req_sizeâ was declared here
  size_t pfp_req_size, me_req_size, ce_req_size, rlc_req_size, mc_req_size;
                                                               ^
drivers/gpu/drm/radeon/si.c:1850:10: warning: ânew_chip_nameâ may be
used uninitialized in this function [-Wmaybe-uninitialized]
  snprintf(fw_name, sizeof(fw_name), "radeon/%s_smc.bin", new_chip_name);
          ^
drivers/gpu/drm/radeon/si.c:1650:14: note: ânew_chip_nameâ was declared here
  const char *new_chip_name;
              ^
drivers/gpu/drm/radeon/si.c:1853:11: warning: âchip_nameâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
   snprintf(fw_name, sizeof(fw_name), "radeon/%s_smc.bin", chip_name);
           ^
drivers/gpu/drm/radeon/si.c:1649:14: note: âchip_nameâ was declared here
  const char *chip_name;
              ^
drivers/gpu/drm/radeon/cik.c: In function âcik_init_microcodeâ:
drivers/gpu/drm/radeon/cik.c:2295:12: warning: ânum_fwâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
  } else if (new_fw < num_fw) {
            ^
drivers/gpu/drm/radeon/cik.c:2186:6: warning: ârlc_req_sizeâ may be
used uninitialized in this function [-Wmaybe-uninitialized]
   if (rdev->rlc_fw->size != rlc_req_size) {
      ^
drivers/gpu/drm/radeon/cik.c:2262:11: warning: ânew_chip_nameâ may be
used uninitialized in this function [-Wmaybe-uninitialized]
   snprintf(fw_name, sizeof(fw_name), "radeon/%s_smc.bin", new_chip_name);
           ^
drivers/gpu/drm/radeon/cik.c:2265:12: warning: âchip_nameâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
    snprintf(fw_name, sizeof(fw_name), "radeon/%s_smc.bin", chip_name);
            ^
drivers/gpu/drm/radeon/rv770_smc.c: In function ârv770_load_smc_ucodeâ:
drivers/gpu/drm/radeon/rv770_smc.c:489:6: warning: âucode_sizeâ may be
used uninitialized in this function [-Wmaybe-uninitialized]
  u16 ucode_size;
      ^
drivers/gpu/drm/radeon/rv770_smc.c:384:70: warning: âint_vectâ may be
used uninitialized in this function [-Wmaybe-uninitialized]
   tmp = (src[i] << 24) | (src[i + 1] << 16) | (src[i + 2] << 8) | src[i + 3];
                                                                      ^
drivers/gpu/drm/radeon/rv770_smc.c:484:12: note: âint_vectâ was declared here
  const u8 *int_vect;
            ^
drivers/gpu/drm/radeon/si_smc.c: In function âsi_load_smc_ucodeâ:
drivers/gpu/drm/radeon/si_smc.c:215:6: warning: âucode_sizeâ may be
used uninitialized in this function [-Wmaybe-uninitialized]
  u32 ucode_size;
      ^
drivers/gpu/drm/drm_crtc.c: In function âdrm_crtc_indexâ:
drivers/gpu/drm/drm_crtc.c:755:1: warning: control reaches end of
non-void function [-Wreturn-type]
 }
 ^
drivers/gpu/drm/drm_crtc.c: In function âdrm_connector_indexâ:
drivers/gpu/drm/drm_crtc.c:1007:1: warning: control reaches end of
non-void function [-Wreturn-type]
 }
 ^
drivers/gpu/drm/drm_crtc.c: In function âdrm_plane_indexâ:
drivers/gpu/drm/drm_crtc.c:1299:1: warning: control reaches end of
non-void function [-Wreturn-type]
 }
 ^
drivers/iommu/dmar.c: In function âdmar_msi_regâ:
drivers/iommu/dmar.c:1510:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
drivers/md/raid0.c: In function âfind_zoneâ:
drivers/md/raid0.c:298:1: warning: control reaches end of non-void
function [-Wreturn-type]
 }
 ^
  CC [M]  drivers/md/raid1.o
  CC [M]  drivers/md/raid10.o
  CC [M]  drivers/md/raid5.o
In file included from ./arch/x86/include/asm/bug.h:48:0,
                 from include/linux/bug.h:4,
                 from include/linux/thread_info.h:11,
                 from ./arch/x86/include/asm/preempt.h:6,
                 from include/linux/preempt.h:59,
                 from include/linux/spinlock.h:50,
                 from include/linux/seqlock.h:35,
                 from include/linux/time.h:5,
                 from include/uapi/linux/timex.h:56,
                 from include/linux/timex.h:56,
                 from include/linux/sched.h:19,
                 from include/linux/blkdev.h:4,
                 from drivers/md/raid5.c:46:
drivers/md/raid5.c: In function âraid_run_opsâ:
include/asm-generic/bug.h:55:35: warning: âtargetâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
 #define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)
                                   ^
drivers/md/raid5.c:1383:6: note: âtargetâ was declared here
  int target;
      ^
drivers/media/common/saa7146/saa7146_fops.c: In function âfops_writeâ:
drivers/media/common/saa7146/saa7146_fops.c:425:1: warning: control
reaches end of non-void function [-Wreturn-type]
 }
 ^
drivers/media/common/saa7146/saa7146_fops.c: In function âfops_readâ:
drivers/media/common/saa7146/saa7146_fops.c:402:1: warning: control
reaches end of non-void function [-Wreturn-type]
 }
 ^
drivers/media/common/saa7146/saa7146_fops.c: In function âfops_mmapâ:
drivers/media/common/saa7146/saa7146_fops.c:318:6: warning: âqâ may be
used uninitialized in this function [-Wmaybe-uninitialized]
  res = videobuf_mmap_mapper(q, vma);
      ^
drivers/media/firewire/firedtv-avc.c: In function âavc_tuner_dsdâ:
drivers/media/firewire/firedtv-avc.c:591:6: warning: âposâ may be used
uninitialized in this function [-Wmaybe-uninitialized]
  int pos, ret;
      ^
drivers/media/pci/pt1/va1j5jf8007s.c: In function âva1j5jf8007s_read_statusâ:
drivers/media/pci/pt1/va1j5jf8007s.c:143:1: warning: control reaches
end of non-void function [-Wreturn-type]
 }
 ^
drivers/media/pci/pt1/va1j5jf8007s.c: In function âva1j5jf8007s_tuneâ:
drivers/media/pci/pt1/va1j5jf8007s.c:508:1: warning: control reaches
end of non-void function [-Wreturn-type]
 }
 ^
  CC [M]  drivers/media/pci/pt1/va1j5jf8007t.o
drivers/media/pci/pt1/va1j5jf8007t.c: In function âva1j5jf8007t_read_statusâ:
drivers/media/pci/pt1/va1j5jf8007t.c:127:1: warning: control reaches
end of non-void function [-Wreturn-type]
 }
 ^
drivers/media/pci/pt1/va1j5jf8007t.c: In function âva1j5jf8007t_tuneâ:
drivers/media/pci/pt1/va1j5jf8007t.c:354:1: warning: control reaches
end of non-void function [-Wreturn-type]
 }
 ^
drivers/media/pci/saa7164/saa7164-encoder.c: In function âsaa7164_s_frequencyâ:
drivers/media/pci/saa7164/saa7164-encoder.c:403:5: warning: âtsportâ
may be used uninitialized in this function [-Wmaybe-uninitialized]
  fe = tsport->dvb.frontend;
     ^