MIPS: smp.c: Fix uninitialised temp_foreign_map

James Hogan · ralfbaechle · commit d825c06bfe8b · 2016-03-13T10:59:19.000+01:00
When calculate_cpu_foreign_map() recalculates the cpu_foreign_map cpumask it uses the local variable temp_foreign_map without initialising it to zero. Since the calculation only ever sets bits in this cpumask any existing bits at that memory location will remain set and find their way into cpu_foreign_map too. This could potentially lead to cache operations suboptimally doing smp calls to multiple VPEs in the same core, even though the VPEs share primary caches. Therefore initialise temp_foreign_map using cpumask_clear() before use. Fixes: cccf34e ("MIPS: c-r4k: Fix cache flushing for MT cores") Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/12759/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/smp.c b/arch/mips/kernel/smp.c
@@ -121,6 +121,7 @@ static inline void calculate_cpu_foreign_map(void)
 	cpumask_t temp_foreign_map;
 
 	/* Re-calculate the mask */
+	cpumask_clear(&temp_foreign_map);
 	for_each_online_cpu(i) {
 		core_present = 0;
 		for_each_cpu(k, &temp_foreign_map)
