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rocker: fix Wmaybe-uninitialized false-positive

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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>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Arnd Bergmann 2017-03-28 16:11:18 +02:00 committed by David S. Miller
parent e497ec680c
commit 16b8b6de32
1 changed files with 4 additions and 7 deletions
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11
drivers/net/ethernet/rocker/rocker_ofdpa.c
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@ -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) {