On Fri, Mar 08, 2019 at 01:14:25PM -0800, Nick Desaulniers wrote: > On Thu, Mar 7, 2019 at 3:19 PM Nathan Chancellor > <natechancellor@xxxxxxxxx> wrote: > > > > When building with -Wsometimes-uninitialized, Clang warns: > > > > drivers/scsi/gdth.c:3662:6: warning: variable 'paddr' is used > > uninitialized whenever 'if' condition is false > > [-Wsometimes-uninitialized] > > > > Don't attempt to call dma_free_coherent when buf is NULL (meaning that > > we never called dma_alloc_coherent and initialized paddr), which avoids > > this warning. > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/402 > > Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx> > > --- > > drivers/scsi/gdth.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/scsi/gdth.c b/drivers/scsi/gdth.c > > index e7f1dd4f3b66..0ca9b4393770 100644 > > --- a/drivers/scsi/gdth.c > > +++ b/drivers/scsi/gdth.c > > @@ -3697,8 +3697,9 @@ static int ioc_general(void __user *arg, char *cmnd) > > > > rval = 0; > > out_free_buf: > > - dma_free_coherent(&ha->pdev->dev, gen.data_len + gen.sense_len, buf, > > - paddr); > > + if (buf) > > + dma_free_coherent(&ha->pdev->dev, gen.data_len + gen.sense_len, > > + buf, paddr); > > return rval; > > } > > > > -- > > 2.21.0 > > > > Alternatively, paddr is a dma_addr_t defined in include/linux/types.h: > > #ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT > typedef u64 dma_addr_t; > #else > typedef u32 dma_addr_t; > #endif > > Just initializing it to zero might be simpler than complicating the > control flow of this function further. Thoughts? > > diff --git a/drivers/scsi/gdth.c b/drivers/scsi/gdth.c > index e7f1dd4f3b66..5a3f849ebf64 100644 > --- a/drivers/scsi/gdth.c > +++ b/drivers/scsi/gdth.c > @@ -3643,7 +3643,7 @@ static int ioc_general(void __user *arg, char *cmnd) > gdth_ioctl_general gen; > gdth_ha_str *ha; > char *buf = NULL; > - dma_addr_t paddr; > + dma_addr_t paddr = 0U; > int rval; > > if (copy_from_user(&gen, arg, sizeof(gdth_ioctl_general))) > -- > Thanks, > ~Nick Desaulniers I suppose it depends on if it's okay to call dma_free_coherent without dma_alloc_coherent. I did a scan of the tree before sending this out and pretty much all sites that have error handling check that the third parameter is not NULL before calling it. I should have added Christoph to this thread when I initially sent it out since commit 9f475ebff8e4 ("scsi: gdth: refactor ioc_general") introduced this. Done now. Cheers, Nathan
