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SubjectRe: [PATCH v2] PCI: rpaphp: Avoid a sometimes-uninitialized warning
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Bjorn Helgaas <helgaas@kernel.org> writes:
> On Mon, Jul 22, 2019 at 02:05:12PM +1000, Michael Ellerman wrote:
>> Nathan Chancellor <natechancellor@gmail.com> writes:
>> > On Mon, Jun 03, 2019 at 03:11:58PM -0700, Nathan Chancellor wrote:
>> >> When building with -Wsometimes-uninitialized, clang warns:
>> >>
>> >> drivers/pci/hotplug/rpaphp_core.c:243:14: warning: variable 'fndit' is
>> >> used uninitialized whenever 'for' loop exits because its condition is
>> >> false [-Wsometimes-uninitialized]
>> >> for (j = 0; j < entries; j++) {
>> >> ^~~~~~~~~~~
>> >> drivers/pci/hotplug/rpaphp_core.c:256:6: note: uninitialized use occurs
>> >> here
>> >> if (fndit)
>> >> ^~~~~
>> >> drivers/pci/hotplug/rpaphp_core.c:243:14: note: remove the condition if
>> >> it is always true
>> >> for (j = 0; j < entries; j++) {
>> >> ^~~~~~~~~~~
>> >> drivers/pci/hotplug/rpaphp_core.c:233:14: note: initialize the variable
>> >> 'fndit' to silence this warning
>> >> int j, fndit;
>> >> ^
>> >> = 0
>> >>
>> >> fndit is only used to gate a sprintf call, which can be moved into the
>> >> loop to simplify the code and eliminate the local variable, which will
>> >> fix this warning.
>> >>
>> >> Link: https://github.com/ClangBuiltLinux/linux/issues/504
>> >> Fixes: 2fcf3ae508c2 ("hotplug/drc-info: Add code to search ibm,drc-info property")
>> >> Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
>> >> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
>> >> ---
>> >>
>> >> v1 -> v2:
>> >>
>> >> * Eliminate fndit altogether by shuffling the sprintf call into the for
>> >> loop and changing the if conditional, as suggested by Nick.
>> >>
>> >> drivers/pci/hotplug/rpaphp_core.c | 18 +++++++-----------
>> >> 1 file changed, 7 insertions(+), 11 deletions(-)
>> >>
>> >> diff --git a/drivers/pci/hotplug/rpaphp_core.c b/drivers/pci/hotplug/rpaphp_core.c
>> >> index bcd5d357ca23..c3899ee1db99 100644
>> >> --- a/drivers/pci/hotplug/rpaphp_core.c
>> >> +++ b/drivers/pci/hotplug/rpaphp_core.c
>> >> @@ -230,7 +230,7 @@ static int rpaphp_check_drc_props_v2(struct device_node *dn, char *drc_name,
>> >> struct of_drc_info drc;
>> >> const __be32 *value;
>> >> char cell_drc_name[MAX_DRC_NAME_LEN];
>> >> - int j, fndit;
>> >> + int j;
>> >>
>> >> info = of_find_property(dn->parent, "ibm,drc-info", NULL);
>> >> if (info == NULL)
>> >> @@ -245,17 +245,13 @@ static int rpaphp_check_drc_props_v2(struct device_node *dn, char *drc_name,
>> >>
>> >> /* Should now know end of current entry */
>> >>
>> >> - if (my_index > drc.last_drc_index)
>> >> - continue;
>> >> -
>> >> - fndit = 1;
>> >> - break;
>> >> + /* Found it */
>> >> + if (my_index <= drc.last_drc_index) {
>> >> + sprintf(cell_drc_name, "%s%d", drc.drc_name_prefix,
>> >> + my_index);
>> >> + break;
>> >> + }
>> >> }
>> >> - /* Found it */
>> >> -
>> >> - if (fndit)
>> >> - sprintf(cell_drc_name, "%s%d", drc.drc_name_prefix,
>> >> - my_index);
>> >>
>> >> if (((drc_name == NULL) ||
>> >> (drc_name && !strcmp(drc_name, cell_drc_name))) &&
>> >> --
>> >> 2.22.0.rc3
>> >>
>> >
>> > Hi all,
>> >
>> > Could someone please pick this up?
>>
>> I'll take it.
>>
>> I was expecting Bjorn to take it as a PCI patch, but I realise now that
>> I merged that code in the first place so may as well take this too.
>>
>> I'll put it in my next branch once that opens next week.
>
> Sorry, I should have done something with this. Did you take it,
> Michael? I don't see it in -next and haven't figured out where to
> look in your git tree, so I can't tell. Just let me know either way
> so I know whether to drop this or apply it.

Yes I have it in my next-test, which will eventually become my next when
I get time to rebase it, test and push etc:

https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/log/?h=next-test

So no further action required on your part.

cheers

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