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From: | Christian Borntraeger |
Subject: | Re: [PATCH for 6.0 v3] hw/intc/i8259: Refactor pic_read_irq() to avoid uninitialized variable |
Date: | Thu, 18 Mar 2021 17:34:16 +0100 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 |
On 18.03.21 17:30, Philippe Mathieu-Daudé wrote:
Some compiler versions are smart enough to detect a potentially uninitialized variable, but are not smart enough to detect that this cannot happen due to the code flow: ../hw/intc/i8259.c: In function ‘pic_read_irq’: ../hw/intc/i8259.c:203:13: error: ‘irq2’ may be used uninitialized in this function [-Werror=maybe-uninitialized] 203 | irq = irq2 + 8; | ~~~~^~~~~~~~~~ Restrict irq2 variable use to the inner statement. Fixes: 78ef2b6989f ("i8259: Reorder intack in pic_read_irq") Reported-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
--- Since v2: - Remove pic_intack() call (Zoltan) --- hw/intc/i8259.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/hw/intc/i8259.c b/hw/intc/i8259.c index 344fd04db14..cc4e21ffec0 100644 --- a/hw/intc/i8259.c +++ b/hw/intc/i8259.c @@ -176,10 +176,12 @@ static void pic_intack(PICCommonState *s, int irq) int pic_read_irq(DeviceState *d) { PICCommonState *s = PIC_COMMON(d); - int irq, irq2, intno; + int irq, intno;irq = pic_get_irq(s);if (irq >= 0) { + int irq2; + if (irq == 2) { irq2 = pic_get_irq(slave_pic); if (irq2 >= 0) { @@ -189,20 +191,18 @@ int pic_read_irq(DeviceState *d) irq2 = 7; } intno = slave_pic->irq_base + irq2; + pic_intack(s, irq); + irq = irq2 + 8; } else { intno = s->irq_base + irq; + pic_intack(s, irq); } - pic_intack(s, irq); } else { /* spurious IRQ on host controller */ irq = 7; intno = s->irq_base + irq; }- if (irq == 2) {- irq = irq2 + 8; - } - #ifdef DEBUG_IRQ_LATENCY printf("IRQ%d latency=%0.3fus\n", irq,
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