Messages in this thread | | | From | Dan Williams <> | Date | Tue, 1 Aug 2017 11:07:48 -0700 | Subject | Re: [PATCH] nvdimm: avoid bogus -Wmaybe-uninitialized warning |
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On Tue, Aug 1, 2017 at 11:00 AM, Ross Zwisler <ross.zwisler@linux.intel.com> wrote: > On Tue, Aug 01, 2017 at 01:48:48PM +0200, Arnd Bergmann wrote: >> Removing the btt_rw_page/pmem_rw_page functions had a surprising >> side-effect of introducing a false-positive warning in another >> function, due to changed inlining decisions in gcc: >> >> In file included from drivers/nvdimm/pmem.c:36:0: >> drivers/nvdimm/pmem.c: In function 'pmem_make_request': >> drivers/nvdimm/nd.h:407:2: error: 'start' may be used uninitialized in this function [-Werror=maybe-uninitialized] >> drivers/nvdimm/pmem.c:174:16: note: 'start' was declared here >> In file included from drivers/nvdimm/btt.c:27:0: >> drivers/nvdimm/btt.c: In function 'btt_make_request': >> drivers/nvdimm/nd.h:407:2: error: 'start' may be used uninitialized in this function [-Werror=maybe-uninitialized] >> drivers/nvdimm/btt.c:1202:16: note: 'start' was declared here >> >> The problem is that gcc fails to track the value of the 'do_acct' >> variable here and has to read it back from stack, but it does >> remember that 'start' may be uninitialized sometimes. >> >> This shuts up the warning by making nd_iostat_start() always >> initialize the 'start' variable. In those cases that gcc successfully >> tracks the state of the variable, this will have no effect. >> >> Fixes: 503a5e89b1de ("drivers/nvdimm/btt.c: remove btt_rw_page()") >> Fixes: 58100d6e735e ("drivers/nvdimm/pmem.c: remove pmem_rw_page()") >> Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > This change looks fine: > > Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> > > I believe the patches removing the btt_rw_page() and btt_rw_page() are on hold > until I can get some performance numbers to justify them. > > Dan, do you want to take this as is, or do you want me to include it in my > larger rw_page() series if/when that gets revived?
I'd say include it with your set.
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