| Message ID | 20170328141126.1541994-1-arnd@arndb.de |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Arnd Bergmann <arnd@arndb.de> Date: Tue, 28 Mar 2017 16:11:18 +0200 > gcc-7 reports a warning that earlier versions did not have: > > drivers/net/ethernet/rocker/rocker_ofdpa.c: In function 'ofdpa_port_stp_update': > arch/x86/include/asm/string_32.h:79:22: error: '*((void *)&prev_ctrls+4)' may be used uninitialized in this function [-Werror=maybe-uninitialized] > *((short *)to + 2) = *((short *)from + 2); > ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~ > drivers/net/ethernet/rocker/rocker_ofdpa.c:2218:7: note: '*((void *)&prev_ctrls+4)' was declared here > > This is clearly a variation of the warning about 'prev_state' that > was shut up using uninitialized_var(). > > We can slightly simplify the code and get rid of the warning by unconditionally > saving the prev_state and prev_ctrls variables. The inlined memcpy is not > particularly expensive here, as it just has to read five bytes from one or > two cache lines. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Applied, thank you.
diff --git a/drivers/net/ethernet/rocker/rocker_ofdpa.c b/drivers/net/ethernet/rocker/rocker_ofdpa.c index 7cd76b6b5cb9..2ae852454780 100644 --- a/drivers/net/ethernet/rocker/rocker_ofdpa.c +++ b/drivers/net/ethernet/rocker/rocker_ofdpa.c @@ -2216,18 +2216,15 @@ static int ofdpa_port_stp_update(struct ofdpa_port *ofdpa_port, { bool want[OFDPA_CTRL_MAX] = { 0, }; bool prev_ctrls[OFDPA_CTRL_MAX]; - u8 uninitialized_var(prev_state); + u8 prev_state; int err; int i; - if (switchdev_trans_ph_prepare(trans)) { - memcpy(prev_ctrls, ofdpa_port->ctrls, sizeof(prev_ctrls)); - prev_state = ofdpa_port->stp_state; - } - - if (ofdpa_port->stp_state == state) + prev_state = ofdpa_port->stp_state; + if (prev_state == state) return 0; + memcpy(prev_ctrls, ofdpa_port->ctrls, sizeof(prev_ctrls)); ofdpa_port->stp_state = state; switch (state) {
gcc-7 reports a warning that earlier versions did not have: drivers/net/ethernet/rocker/rocker_ofdpa.c: In function 'ofdpa_port_stp_update': arch/x86/include/asm/string_32.h:79:22: error: '*((void *)&prev_ctrls+4)' may be used uninitialized in this function [-Werror=maybe-uninitialized] *((short *)to + 2) = *((short *)from + 2); ~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~ drivers/net/ethernet/rocker/rocker_ofdpa.c:2218:7: note: '*((void *)&prev_ctrls+4)' was declared here This is clearly a variation of the warning about 'prev_state' that was shut up using uninitialized_var(). We can slightly simplify the code and get rid of the warning by unconditionally saving the prev_state and prev_ctrls variables. The inlined memcpy is not particularly expensive here, as it just has to read five bytes from one or two cache lines. Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/net/ethernet/rocker/rocker_ofdpa.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-)