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Commit 06a901c5621f85e07e00ac4816c7ca95620ee74a

Authored by Stephen Rothwell
Committed by Paul Mackerras
1 parent d1e8d50d5a
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

[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: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

Showing 2 changed files with 4 additions and 19 deletions Side-by-side Diff

arch/powerpc/sysdev/mpic.c
Diff comments   View file @ 06a901c
... ... @@ -1331,6 +1331,9 @@
1331 1331 unsigned long flags;
1332 1332 u32 reg;
1333 1333  
  1334 + if (!mpic)
  1335 + return;
  1336 +
1334 1337 spin_lock_irqsave(&mpic_lock, flags);
1335 1338 if (is_ipi) {
1336 1339 reg = mpic_ipi_read(src - mpic->ipi_vecs[0]) &
... ... @@ -1344,23 +1347,6 @@
1344 1347 reg | (pri << MPIC_VECPRI_PRIORITY_SHIFT));
1345 1348 }
1346 1349 spin_unlock_irqrestore(&mpic_lock, flags);
1347   -}
1348   -
1349   -unsigned int mpic_irq_get_priority(unsigned int irq)
1350   -{
1351   - unsigned int is_ipi;
1352   - struct mpic *mpic = mpic_find(irq, &is_ipi);
1353   - unsigned int src = mpic_irq_to_hw(irq);
1354   - unsigned long flags;
1355   - u32 reg;
1356   -
1357   - spin_lock_irqsave(&mpic_lock, flags);
1358   - if (is_ipi)
1359   - reg = mpic_ipi_read(src = mpic->ipi_vecs[0]);
1360   - else
1361   - reg = mpic_irq_read(src, MPIC_INFO(IRQ_VECTOR_PRI));
1362   - spin_unlock_irqrestore(&mpic_lock, flags);
1363   - return (reg & MPIC_VECPRI_PRIORITY_MASK) >> MPIC_VECPRI_PRIORITY_SHIFT;
1364 1350 }
1365 1351  
1366 1352 void mpic_setup_this_cpu(void)
include/asm-powerpc/mpic.h
Diff comments   View file @ 06a901c
... ... @@ -428,12 +428,11 @@
428 428 */
429 429  
430 430  
431   -/* Change/Read the priority of an interrupt. Default is 8 for irqs and
  431 +/* Change the priority of an interrupt. Default is 8 for irqs and
432 432 * 10 for IPIs. You can call this on both IPIs and IRQ numbers, but the
433 433 * IPI number is then the offset'ed (linux irq number mapped to the IPI)
434 434 */
435 435 extern void mpic_irq_set_priority(unsigned int irq, unsigned int pri);
436   -extern unsigned int mpic_irq_get_priority(unsigned int irq);
437 436  
438 437 /* Setup a non-boot CPU */
439 438 extern void mpic_setup_this_cpu(void);