ARM: OMAP2+: Fix -Warray-bounds warning in _pwrdm_state_switch()

If function pwrdm_read_prev_pwrst() returns -EINVAL, we will end up accessing array pwrdm->state_counter through negative index -22. This is wrong and the compiler is legitimately warning us about this potential problem.

Fix this by sanity checking the value stored in variable _prev_ before accessing array pwrdm->state_counter.

Address the following -Warray-bounds warning:
arch/arm/mach-omap2/powerdomain.c:178:45: warning: array subscript -22 is below array bounds of 'unsigned int[4]' [-Warray-bounds]

Link https://github.com/KSPP/linux/issues/307

Fixes ba20bb126940 ("OMAP: PM counter infrastructure.")

Cc [email protected]

Reported-by kernel test robot <[email protected]>

Link https://lore.kernel.org/lkml/20230607050639.LzbPn%[email protected]/ open here

Signed-off-by Gustavo A. R. Silva <[email protected]>

---
 arch/arm/mach-omap2/powerdomain.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

arch/arm/mach-omap2/powerdomain.c +1 -2

index 777f9f8e7cd8..5e05dd1324e7 100644
@@ -174,7 +174,7 @@ static int _pwrdm_state_switch(struct powerdomain *pwrdm, int flag)
                break;
        case PWRDM_STATE_PREV:
                prev = pwrdm_read_prev_pwrst(pwrdm);
-               if (pwrdm->state != prev)
+               if (prev >= 0 && pwrdm->state != prev)
                        pwrdm->state_counter[prev]++;
                if (prev == PWRDM_POWER_RET)
                        _update_logic_membank_counters(pwrdm);
--

2.34.1

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If function pwrdm_read_prev_pwrst() returns -EINVAL, we will end up accessing array pwrdm->state_counter through negative index -22. This is wrong and the compiler is legitimately warning us about this potential problem.

Fix this by sanity checking the value stored in variable _prev_ before accessing array pwrdm->state_counter.

Address the following -Warray-bounds warning:
arch/arm/mach-omap2/powerdomain.c:178:45: warning: array subscript -22 is below array bounds of 'unsigned int[4]' [-Warray-bounds]