| Message ID | 20220810114318.3220630-1-anders.roxell@linaro.org (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | d78c8e32890ef7eca79ffd67c96022c7f9d8cce4 |
| Headers | show |
| Series | [PATCHv3,resend] powerpc: mm: radix_tlb: rearrange the if-else block | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/github-powerpc_ppctests | success | Successfully ran 10 jobs. |
| snowpatch_ozlabs/github-powerpc_selftests | success | Successfully ran 10 jobs. |
| snowpatch_ozlabs/github-powerpc_sparse | success | Successfully ran 4 jobs. |
| snowpatch_ozlabs/github-powerpc_clang | success | Successfully ran 6 jobs. |
| snowpatch_ozlabs/github-powerpc_kernel_qemu | success | Successfully ran 23 jobs. |
Hi! On Wed, Aug 10, 2022 at 01:43:18PM +0200, Anders Roxell wrote: > Clang warns: > > arch/powerpc/mm/book3s64/radix_tlb.c:1191:23: error: variable 'hstart' is uninitialized when used here [-Werror,-Wuninitialized] > __tlbiel_va_range(hstart, hend, pid, > ^~~~~~ > arch/powerpc/mm/book3s64/radix_tlb.c:1175:23: note: initialize the variable 'hstart' to silence this warning This note often is bad advice: hiding problems instead of investigating and solving them. Bah. If silencing warnings is your goal, look no further than "-w" :-) > Rework the 'if (IS_ENABLE(CONFIG_TRANSPARENT_HUGEPAGE))' so hstart/hend > always gets initialized, this will silence the warnings. That will also > simplify the 'else' path. Clang is getting confused with these warnings, > but the warnings is a false-positive. If it is, please report that bug to clang? It says "*is* uninitialized when used here", there can not be false positives to statements like that. If the analysis was heutistical it should say "may be" or such. Segher
Anders Roxell <anders.roxell@linaro.org> writes: > Clang warns: > > arch/powerpc/mm/book3s64/radix_tlb.c:1191:23: error: variable 'hstart' is uninitialized when used here [-Werror,-Wuninitialized] > __tlbiel_va_range(hstart, hend, pid, > ^~~~~~ > arch/powerpc/mm/book3s64/radix_tlb.c:1175:23: note: initialize the variable 'hstart' to silence this warning > unsigned long hstart, hend; > ^ > = 0 > arch/powerpc/mm/book3s64/radix_tlb.c:1191:31: error: variable 'hend' is uninitialized when used here [-Werror,-Wuninitialized] > __tlbiel_va_range(hstart, hend, pid, > ^~~~ > arch/powerpc/mm/book3s64/radix_tlb.c:1175:29: note: initialize the variable 'hend' to silence this warning > unsigned long hstart, hend; > ^ > = 0 > 2 errors generated. Which version & config are you building? I don't see this warning in my test builds. cheers
On Thu, 11 Aug 2022 at 11:41, Michael Ellerman <mpe@ellerman.id.au> wrote: > > Anders Roxell <anders.roxell@linaro.org> writes: > > Clang warns: > > > > arch/powerpc/mm/book3s64/radix_tlb.c:1191:23: error: variable 'hstart' is uninitialized when used here [-Werror,-Wuninitialized] > > __tlbiel_va_range(hstart, hend, pid, > > ^~~~~~ > > arch/powerpc/mm/book3s64/radix_tlb.c:1175:23: note: initialize the variable 'hstart' to silence this warning > > unsigned long hstart, hend; > > ^ > > = 0 > > arch/powerpc/mm/book3s64/radix_tlb.c:1191:31: error: variable 'hend' is uninitialized when used here [-Werror,-Wuninitialized] > > __tlbiel_va_range(hstart, hend, pid, > > ^~~~ > > arch/powerpc/mm/book3s64/radix_tlb.c:1175:29: note: initialize the variable 'hend' to silence this warning > > unsigned long hstart, hend; > > ^ > > = 0 > > 2 errors generated. > > Which version & config are you building? clang-13, clang-14 and clang-nightly, configs are cell_defconfig and maple_defconfig I'm building with tuxmake [1] like this: $ tuxmake --runtime podman --target-arch powerpc --toolchain clang-14 --kconfig cell_defconfig Cheers, Anders [1] https://tuxmake.org/
On Wed, 10 Aug 2022 13:43:18 +0200, Anders Roxell wrote: > Clang warns: > > arch/powerpc/mm/book3s64/radix_tlb.c:1191:23: error: variable 'hstart' is uninitialized when used here [-Werror,-Wuninitialized] > __tlbiel_va_range(hstart, hend, pid, > ^~~~~~ > arch/powerpc/mm/book3s64/radix_tlb.c:1175:23: note: initialize the variable 'hstart' to silence this warning > unsigned long hstart, hend; > ^ > = 0 > arch/powerpc/mm/book3s64/radix_tlb.c:1191:31: error: variable 'hend' is uninitialized when used here [-Werror,-Wuninitialized] > __tlbiel_va_range(hstart, hend, pid, > ^~~~ > arch/powerpc/mm/book3s64/radix_tlb.c:1175:29: note: initialize the variable 'hend' to silence this warning > unsigned long hstart, hend; > ^ > = 0 > 2 errors generated. > > [...] Applied to powerpc/next. [1/1] powerpc: mm: radix_tlb: rearrange the if-else block https://git.kernel.org/powerpc/c/d78c8e32890ef7eca79ffd67c96022c7f9d8cce4 cheers
diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c index 4e29b619578c..6d7a1ef723e6 100644 --- a/arch/powerpc/mm/book3s64/radix_tlb.c +++ b/arch/powerpc/mm/book3s64/radix_tlb.c @@ -1179,15 +1179,12 @@ static inline void __radix__flush_tlb_range(struct mm_struct *mm, } } } else { - bool hflush = false; + bool hflush; unsigned long hstart, hend; - if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) { - hstart = (start + PMD_SIZE - 1) & PMD_MASK; - hend = end & PMD_MASK; - if (hstart < hend) - hflush = true; - } + hstart = (start + PMD_SIZE - 1) & PMD_MASK; + hend = end & PMD_MASK; + hflush = IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && hstart < hend; if (type == FLUSH_TYPE_LOCAL) { asm volatile("ptesync": : :"memory");
Clang warns: arch/powerpc/mm/book3s64/radix_tlb.c:1191:23: error: variable 'hstart' is uninitialized when used here [-Werror,-Wuninitialized] __tlbiel_va_range(hstart, hend, pid, ^~~~~~ arch/powerpc/mm/book3s64/radix_tlb.c:1175:23: note: initialize the variable 'hstart' to silence this warning unsigned long hstart, hend; ^ = 0 arch/powerpc/mm/book3s64/radix_tlb.c:1191:31: error: variable 'hend' is uninitialized when used here [-Werror,-Wuninitialized] __tlbiel_va_range(hstart, hend, pid, ^~~~ arch/powerpc/mm/book3s64/radix_tlb.c:1175:29: note: initialize the variable 'hend' to silence this warning unsigned long hstart, hend; ^ = 0 2 errors generated. Rework the 'if (IS_ENABLE(CONFIG_TRANSPARENT_HUGEPAGE))' so hstart/hend always gets initialized, this will silence the warnings. That will also simplify the 'else' path. Clang is getting confused with these warnings, but the warnings is a false-positive. Suggested-by: Arnd Bergmann <arnd@arndb.de> Suggested-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Anders Roxell <anders.roxell@linaro.org> --- arch/powerpc/mm/book3s64/radix_tlb.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-)