On Tue, Jul 09, 2019 at 04:05:53PM -0700, Nathan Chancellor wrote:
> clang warns:
>
> drivers/infiniband/sw/rdmavt/cq.c:260:7: warning: variable 'err' is used
> uninitialized whenever 'if' condition is true
> [-Wsometimes-uninitialized]
> if (err)
> ^~~
> drivers/infiniband/sw/rdmavt/cq.c:310:9: note: uninitialized use occurs
> here
> return err;
> ^~~
> drivers/infiniband/sw/rdmavt/cq.c:260:3: note: remove the 'if' if its
> condition is always false
> if (err)
> ^~~~~~~~
> drivers/infiniband/sw/rdmavt/cq.c:253:7: warning: variable 'err' is used
> uninitialized whenever 'if' condition is true
> [-Wsometimes-uninitialized]
> if (!cq->ip) {
> ^~~~~~~
> drivers/infiniband/sw/rdmavt/cq.c:310:9: note: uninitialized use occurs
> here
> return err;
> ^~~
> drivers/infiniband/sw/rdmavt/cq.c:253:3: note: remove the 'if' if its
> condition is always false
> if (!cq->ip) {
> ^~~~~~~~~~~~~~
> drivers/infiniband/sw/rdmavt/cq.c:211:9: note: initialize the variable
> 'err' to silence this warning
> int err;
> ^
> = 0
> 2 warnings generated.
What version of the kernel was this found on?
I don't see the problem with 5.2. AFAICS there is no 'err' in the function
scope and the if scoped 'err' is initialized properly on line 239.
Ira
>
> The function scoped err variable is uninitialized when the flow jumps
> into the if statement. The if scoped err variable shadows the function
> scoped err variable, preventing the err assignments within the if
> statement to be reflected at the function level, which will cause
> uninitialized use when the goto statements are taken.
>
> Just remove the if scoped err declaration so that there is only one
> copy of the err variable for this function.
>
> Fixes: 239b0e52d8aa ("IB/hfi1: Move rvt_cq_wc struct into uapi directory")
> Link: https://github.com/ClangBuiltLinux/linux/issues/594
> Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
> ---
>
> v1 -> v2:
>
> * Updated the wording of the commit message to use proper terms like
> scoping and shadowing, thanks to review from Nick (let me know if the
> wording isn't up to snuff).
>
> drivers/infiniband/sw/rdmavt/cq.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/drivers/infiniband/sw/rdmavt/cq.c b/drivers/infiniband/sw/rdmavt/cq.c
> index fac87b13329d..a85571a4cf57 100644
> --- a/drivers/infiniband/sw/rdmavt/cq.c
> +++ b/drivers/infiniband/sw/rdmavt/cq.c
> @@ -247,8 +247,6 @@ int rvt_create_cq(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
> * See rvt_mmap() for details.
> */
> if (udata && udata->outlen >= sizeof(__u64)) {
> - int err;
> -
> cq->ip = rvt_create_mmap_info(rdi, sz, udata, u_wc);
> if (!cq->ip) {
> err = -ENOMEM;
> --
> 2.22.0
>
