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Commit 06a901c5 authored by Stephen Rothwell's avatar Stephen Rothwell Committed by Paul Mackerras
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[POWERPC] mpic: Fix use of uninitialized variable 



Compiling ppc64_defconfig with gcc 4.3 gives thes warnings:

arch/powerpc/sysdev/mpic.c: In function 'mpic_irq_get_priority':
arch/powerpc/sysdev/mpic.c:1351: warning: 'is_ipi' may be used uninitialized in this function
arch/powerpc/sysdev/mpic.c: In function 'mpic_irq_set_priority':
arch/powerpc/sysdev/mpic.c:1328: warning: 'is_ipi' may be used uninitialized in this function

It turns out that in the cases where is_ipi is uninitialized, another
variable (mpic) will be NULL and it is dereferenced.  Protect against
this by returning if mpic is NULL in mpic_irq_set_priority, and removing
mpic_irq_get_priority completely as it has no in tree callers.

This has the nice side effect of making the warning go away.

Signed-off-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
Acked-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent d1e8d50d

arch/powerpc/sysdev/mpic.c

+3 −17
Original line number Diff line number Diff line
@@ -1331,6 +1331,9 @@ void mpic_irq_set_priority(unsigned int irq, unsigned int pri) 
	unsigned long flags;

	u32 reg;



	if (!mpic)

		return;



	spin_lock_irqsave(&mpic_lock, flags);

	if (is_ipi) {

		reg = mpic_ipi_read(src - mpic->ipi_vecs[0]) &
@@ -1346,23 +1349,6 @@ void mpic_irq_set_priority(unsigned int irq, unsigned int pri) 
	spin_unlock_irqrestore(&mpic_lock, flags);

}



unsigned int mpic_irq_get_priority(unsigned int irq)

{

	unsigned int is_ipi;

	struct mpic *mpic = mpic_find(irq, &is_ipi);

	unsigned int src = mpic_irq_to_hw(irq);

	unsigned long flags;

	u32 reg;



	spin_lock_irqsave(&mpic_lock, flags);

	if (is_ipi)

		reg = mpic_ipi_read(src = mpic->ipi_vecs[0]);

	else

		reg = mpic_irq_read(src, MPIC_INFO(IRQ_VECTOR_PRI));

	spin_unlock_irqrestore(&mpic_lock, flags);

	return (reg & MPIC_VECPRI_PRIORITY_MASK) >> MPIC_VECPRI_PRIORITY_SHIFT;

}



void mpic_setup_this_cpu(void)

{

#ifdef CONFIG_SMP

include/asm-powerpc/mpic.h

+1 −2
Original line number Diff line number Diff line
@@ -428,12 +428,11 @@ extern void mpic_init(struct mpic *mpic); 
 */





/* Change/Read the priority of an interrupt. Default is 8 for irqs and

/* Change the priority of an interrupt. Default is 8 for irqs and

 * 10 for IPIs. You can call this on both IPIs and IRQ numbers, but the

 * IPI number is then the offset'ed (linux irq number mapped to the IPI)

 */

extern void mpic_irq_set_priority(unsigned int irq, unsigned int pri);

extern unsigned int mpic_irq_get_priority(unsigned int irq);



/* Setup a non-boot CPU */

extern void mpic_setup_this_cpu(void);