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Miller" Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Nick Desaulniers , clang-built-linux@googlegroups.com Subject: Re: -Wsometimes-uninitialized Clang warning in drivers/net/ethernet/broadcom/bnxt/bnxt.c Message-ID: <20190320190849.GB28744@archlinux-ryzen> References: <20190308005735.GA4122@archlinux-ryzen> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190308005735.GA4122@archlinux-ryzen> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 07, 2019 at 05:57:35PM -0700, Nathan Chancellor wrote: > Hi all, > > We are trying to get Clang's -Wsometimes-uninitialized turned on for the > kernel as it can catch some bugs that GCC can't. This warning came up: > > drivers/net/ethernet/broadcom/bnxt/bnxt.c:1612:6: warning: variable 'len' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] > if (rxcmp1->rx_cmp_cfa_code_errors_v2 & RX_CMP_L2_ERRORS) { > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > drivers/net/ethernet/broadcom/bnxt/bnxt.c:1703:19: note: uninitialized use occurs here > cpr->rx_bytes += len; > ^~~ > drivers/net/ethernet/broadcom/bnxt/bnxt.c:1612:2: note: remove the 'if' if its condition is always false > if (rxcmp1->rx_cmp_cfa_code_errors_v2 & RX_CMP_L2_ERRORS) { > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > drivers/net/ethernet/broadcom/bnxt/bnxt.c:1540:18: note: initialize the variable 'len' to silence this warning > unsigned int len; > ^ > = 0 > 1 warning generated. > > It seems like the logical change to make is this; however, I am not sure > if this has any other unintended consequences since this is a rather > dense function. I would much appreciate your input, especially if there > is a better way to fix it. > > Cheers, > Nathan > > diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c > index 0bb9d7b3a2b6..7d3d206c2e86 100644 > --- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c > +++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c > @@ -1615,7 +1615,7 @@ static int bnxt_rx_pkt(struct bnxt *bp, struct bnxt_cp_ring_info *cpr, > bnxt_reuse_rx_agg_bufs(cpr, cp_cons, agg_bufs); > > rc = -EIO; > - goto next_rx; > + goto next_rx_no_prod_no_len; > } > > len = le32_to_cpu(rxcmp->rx_cmp_len_flags_type) >> RX_CMP_LEN_SHIFT; Gentle ping (if there was a response to this, I didn't receive it). I know I sent it in the middle of a merge window so I get if it slipped through the cracks. Thanks, Nathan