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-Wself-assign in drivers/net/fddi/skfp/pcmplc.c #128

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tpimh opened this issue Sep 20, 2018 · 3 comments
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-Wself-assign in drivers/net/fddi/skfp/pcmplc.c #128

tpimh opened this issue Sep 20, 2018 · 3 comments
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@nathanchance
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-Wself-assign [BUG] linux A bug that should be fixed in the mainline kernel. [FIXED][LINUX] 4.20 This bug was fixed in Linux 4.20

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@tpimh
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tpimh commented Sep 20, 2018 

drivers/net/fddi/skfp/pcmplc.c:1257:6: warning: explicitly assigning value of variable
      of type 'int' to itself [-Wself-assign]
        phy = phy ; on_off = on_off ;
        ~~~ ^ ~~~
drivers/net/fddi/skfp/pcmplc.c:1257:21: warning: explicitly assigning value of variable
      of type 'int' to itself [-Wself-assign]
        phy = phy ; on_off = on_off ;
                    ~~~~~~ ^ ~~~~~~
2 warnings generated.
@tpimh tpimh added [BUG] linux A bug that should be fixed in the mainline kernel. low priority This bug is not critical and not a priority labels Sep 20, 2018
@nathanchance
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Patch sent: https://lore.kernel.org/lkml/20180920223632.14113-1-natechancellor@gmail.com/

@nathanchance nathanchance self-assigned this Sep 20, 2018
@nathanchance nathanchance added [PATCH] Exists There is a patch that fixes this issue [PATCH] Submitted A patch has been submitted for review and removed [PATCH] Exists There is a patch that fixes this issue labels Sep 20, 2018
fengguang pushed a commit to 0day-ci/linux that referenced this issue Sep 21, 2018
@nathanchance @intel-lab-lkp
net: fddi: skfp: Remove unused function
fb52756 
Clang warns when a variable is assigned to itself.

drivers/net/fddi/skfp/pcmplc.c:1257:6: warning: explicitly assigning
value of variable of type 'int' to itself [-Wself-assign]
        phy = phy ; on_off = on_off ;
        ~~~ ^ ~~~
drivers/net/fddi/skfp/pcmplc.c:1257:21: warning: explicitly assigning
value of variable of type 'int' to itself [-Wself-assign]
        phy = phy ; on_off = on_off ;
                    ~~~~~~ ^ ~~~~~~
2 warnings generated.

Turns out this entire function doesn't actually do anything since
SK_UNUSED is just casting the pointer to void. Remove it to silence
this Clang warning.

Link: ClangBuiltLinux#128
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
alaahl pushed a commit to alaahl/linux that referenced this issue Sep 22, 2018
@nathanchance @davem330
net: fddi: skfp: Remove unused function
6b8e327 
Clang warns when a variable is assigned to itself.

drivers/net/fddi/skfp/pcmplc.c:1257:6: warning: explicitly assigning
value of variable of type 'int' to itself [-Wself-assign]
        phy = phy ; on_off = on_off ;
        ~~~ ^ ~~~
drivers/net/fddi/skfp/pcmplc.c:1257:21: warning: explicitly assigning
value of variable of type 'int' to itself [-Wself-assign]
        phy = phy ; on_off = on_off ;
                    ~~~~~~ ^ ~~~~~~
2 warnings generated.

Turns out this entire function doesn't actually do anything since
SK_UNUSED is just casting the pointer to void. Remove it to silence
this Clang warning.

Link: ClangBuiltLinux#128
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
@nathanchance
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Patch accepted: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/commit/?id=6b8e327cfa2dfb9da2bd70326494a1f5ca9968f7

@nathanchance nathanchance added [PATCH] Accepted A submitted patch has been accepted upstream and removed [PATCH] Submitted A patch has been submitted for review labels Sep 23, 2018
@nathanchance
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Merged into mainline: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6b8e327cfa2dfb9da2bd70326494a1f5ca9968f7

@nathanchance nathanchance added [FIXED][LINUX] 4.20 This bug was fixed in Linux 4.20 and removed [PATCH] Accepted A submitted patch has been accepted upstream labels Oct 25, 2018
@tpimh tpimh removed the low priority This bug is not critical and not a priority label Oct 26, 2018
nathanchance pushed a commit that referenced this issue Apr 5, 2020
@kvaneesh @mpe
powerpc/hash64/devmap: Use H_PAGE_THP_HUGE when setting up huge devma…
36b7840 
…p PTE entries

H_PAGE_THP_HUGE is used to differentiate between a THP hugepage and
hugetlb hugepage entries. The difference is WRT how we handle hash
fault on these address. THP address enables MPSS in segments. We want
to manage devmap hugepage entries similar to THP pt entries. Hence use
H_PAGE_THP_HUGE for devmap huge PTE entries.

With current code while handling hash PTE fault, we do set is_thp =
true when finding devmap PTE huge PTE entries.

Current code also does the below sequence we setting up huge devmap
entries.

	entry = pmd_mkhuge(pfn_t_pmd(pfn, prot));
	if (pfn_t_devmap(pfn))
		entry = pmd_mkdevmap(entry);

In that case we would find both H_PAGE_THP_HUGE and PAGE_DEVMAP set
for huge devmap PTE entries. This results in false positive error like
below.

  kernel BUG at /home/kvaneesh/src/linux/mm/memory.c:4321!
  Oops: Exception in kernel mode, sig: 5 [#1]
  LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
  Modules linked in:
  CPU: 56 PID: 67996 Comm: t_mmap_dio Not tainted 5.6.0-rc4-59640-g371c804dedbc #128
  ....
  NIP [c00000000044c9e4] __follow_pte_pmd+0x264/0x900
  LR [c0000000005d45f8] dax_writeback_one+0x1a8/0x740
  Call Trace:
    str_spec.74809+0x22ffb4/0x2d116c (unreliable)
    dax_writeback_one+0x1a8/0x740
    dax_writeback_mapping_range+0x26c/0x700
    ext4_dax_writepages+0x150/0x5a0
    do_writepages+0x68/0x180
    __filemap_fdatawrite_range+0x138/0x180
    file_write_and_wait_range+0xa4/0x110
    ext4_sync_file+0x370/0x6e0
    vfs_fsync_range+0x70/0xf0
    sys_msync+0x220/0x2e0
    system_call+0x5c/0x68

This is because our pmd_trans_huge check doesn't exclude _PAGE_DEVMAP.

To make this all consistent, update pmd_mkdevmap to set
H_PAGE_THP_HUGE and pmd_trans_huge check now excludes _PAGE_DEVMAP
correctly.

Fixes: ebd3119 ("powerpc/mm: Add devmap support for ppc64")
Cc: stable@vger.kernel.org # v4.13+
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200313094842.351830-1-aneesh.kumar@linux.ibm.com
nathanchance pushed a commit that referenced this issue Oct 15, 2020
@bebarino @robclark
drm/msm: Avoid div-by-zero in dpu_crtc_atomic_check()
22f7609 
The cstate->num_mixers member is only set to a non-zero value once
dpu_encoder_virt_mode_set() is called, but the atomic check function can
be called by userspace before that. Let's avoid the div-by-zero here and
inside _dpu_crtc_setup_lm_bounds() by skipping this part of the atomic
check if dpu_encoder_virt_mode_set() hasn't been called yet. This fixes
an UBSAN warning:

 UBSAN: Undefined behaviour in drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c:860:31
 division by zero
 CPU: 7 PID: 409 Comm: frecon Tainted: G S                5.4.31 #128
 Hardware name: Google Trogdor (rev0) (DT)
 Call trace:
  dump_backtrace+0x0/0x14c
  show_stack+0x20/0x2c
  dump_stack+0xa0/0xd8
  __ubsan_handle_divrem_overflow+0xec/0x110
  dpu_crtc_atomic_check+0x97c/0x9d4
  drm_atomic_helper_check_planes+0x160/0x1c8
  drm_atomic_helper_check+0x54/0xbc
  drm_atomic_check_only+0x6a8/0x880
  drm_atomic_commit+0x20/0x5c
  drm_atomic_helper_set_config+0x98/0xa0
  drm_mode_setcrtc+0x308/0x5dc
  drm_ioctl_kernel+0x9c/0x114
  drm_ioctl+0x2ac/0x4b0
  drm_compat_ioctl+0xe8/0x13c
  __arm64_compat_sys_ioctl+0x184/0x324
  el0_svc_common+0xa4/0x154
  el0_svc_compat_handler+0x

Cc: Abhinav Kumar <abhinavk@codeaurora.org>
Cc: Jeykumar Sankaran <jsanka@codeaurora.org>
Cc: Jordan Crouse <jcrouse@codeaurora.org>
Cc: Sean Paul <seanpaul@chromium.org>
Fixes: 25fdd59 ("drm/msm: Add SDM845 DPU support")
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Abhinav Kumar <abhinavk@codeaurora.org>
Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>
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-Wself-assign [BUG] linux A bug that should be fixed in the mainline kernel. [FIXED][LINUX] 4.20 This bug was fixed in Linux 4.20
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