Commit 16b8b6de authored Mar 28, 2017 by Arnd Bergmann Committed by David S. Miller Mar 28, 2017

rocker: fix Wmaybe-uninitialized false-positive



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>

parent e497ec68

drivers/net/ethernet/rocker/rocker_ofdpa.c

+4 −7

Original line number	Diff line number	Diff line
		@@ -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)
		if (prev_state == state)
		return 0;

		memcpy(prev_ctrls, ofdpa_port->ctrls, sizeof(prev_ctrls));
		ofdpa_port->stp_state = state;

		switch (state) {