Messages in this thread | | | Date | Tue, 1 Aug 2017 12:00:17 -0600 | From | Ross Zwisler <> | Subject | Re: [PATCH] nvdimm: avoid bogus -Wmaybe-uninitialized warning |
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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?
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