Re: [PATCH v2] IB/rdmavt: Fix variable shadowing issue in rvt_create_cq

From: Jason Gunthorpe <jgg@ziepe.ca>
To: Nathan Chancellor <natechancellor@gmail.com>,
	Mike Marciniszyn <mike.marciniszyn@intel.com>
Cc: Dennis Dalessandro <dennis.dalessandro@intel.com>,
	Mike Marciniszyn <mike.marciniszyn@intel.com>,
	Doug Ledford <dledford@redhat.com>,
	Kamenee Arumugam <kamenee.arumugam@intel.com>,
	linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org,
	clang-built-linux@googlegroups.com,
	Nick Desaulniers <ndesaulniers@google.com>
Subject: Re: [PATCH v2] IB/rdmavt: Fix variable shadowing issue in rvt_create_cq
Date: Wed, 10 Jul 2019 14:02:16 -0300	[thread overview]
Message-ID: <20190710170216.GA15103@ziepe.ca> (raw)
In-Reply-To: <20190709230552.61842-1-natechancellor@gmail.com>

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.
> 
> 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@google.com>
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>

Applied to for-next with Mike's ack

Thanks,
Jason