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Miller" Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Nick Desaulniers , clang-built-linux@googlegroups.com Subject: -Wsometimes-uninitialized Clang warning in drivers/net/ethernet/broadcom/bnxt/bnxt.c Message-ID: <20190308005735.GA4122@archlinux-ryzen> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.11.3 (2019-02-01) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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;