On Tue, 18 Oct 2016 00:16:13 +0200 Arnd Bergmann <a...@arndb.de> wrote:
> gcc correctly warns about an incorrect use of the 'pa' variable > in case we pass an empty scatterlist to __s390_dma_map_sg: > > arch/s390/pci/pci_dma.c: In function '__s390_dma_map_sg': > arch/s390/pci/pci_dma.c:309:13: warning: 'pa' may be used uninitialized in > this function [-Wmaybe-uninitialized] > > This adds a bogus initialization to the function to sanitize > the debug output. I would have preferred a solution without > the initialization, but I only got the report from the > kbuild bot after turning on the warning again, and didn't > manage to reproduce it myself. > > Signed-off-by: Arnd Bergmann <a...@arndb.de> > --- > arch/s390/pci/pci_dma.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/s390/pci/pci_dma.c b/arch/s390/pci/pci_dma.c > index 7350c8b..6b2f72f 100644 > --- a/arch/s390/pci/pci_dma.c > +++ b/arch/s390/pci/pci_dma.c > @@ -423,7 +423,7 @@ static int __s390_dma_map_sg(struct device *dev, struct > scatterlist *sg, > dma_addr_t dma_addr_base, dma_addr; > int flags = ZPCI_PTE_VALID; > struct scatterlist *s; > - unsigned long pa; > + unsigned long pa = 0; > int ret; > > size = PAGE_ALIGN(size); The compiler is right. pa is set in the for-loop. If "dma_addr < dma_addr_base + size" is never true and __dma_purge_tlb() returns with an error, pa *is* uninitialized. The fix seems sensible to me. -- blue skies, Martin. "Reality continues to ruin my life." - Calvin.
