[PATCH 2/2] powerpc/xive: rework xive_find_target_in_mask()

[Yury Norov <ynorov@nvidia.com>]

Switch the function to using modern cpumask API and drop most of the
housekeeping code.

Notice, if first >= nr_cpu_ids, for_each_cpu_wrap() iterator behaves just
like for_each_cpu(), i.e. begins from 0. So even if WARN_ON() is triggered,
no special handling is needed.

Signed-off-by: Yury Norov <ynorov@nvidia.com>
---
 arch/powerpc/sysdev/xive/common.c | 31 ++++++-------------------------
 1 file changed, 6 insertions(+), 25 deletions(-)

diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c
index e91ec9036ad8..4e05f678e171 100644
--- a/arch/powerpc/sysdev/xive/common.c
+++ b/arch/powerpc/sysdev/xive/common.c
@@ -548,40 +548,21 @@ static void xive_dec_target_count(int cpu)
 static int xive_find_target_in_mask(const struct cpumask *mask,
 				    unsigned int fuzz)
 {
-	int cpu, first, num, i;
+	int cpu, first;
 
 	/* Pick up a starting point CPU in the mask based on  fuzz */
-	num = cpumask_weight(mask);
-	first = fuzz % num;
-
-	/* Locate it */
-	cpu = cpumask_first(mask);
-	for (i = 0; i < first && cpu < nr_cpu_ids; i++)
-		cpu = cpumask_next(cpu, mask);
-
-	/* Sanity check */
-	if (WARN_ON(cpu >= nr_cpu_ids))
-		cpu = cpumask_first(cpu_online_mask);
-
-	/* Remember first one to handle wrap-around */
-	first = cpu;
+	fuzz %= cpumask_weight(mask);
+	first = cpumask_nth(fuzz, mask);
+	WARN_ON(first >= nr_cpu_ids);
 
 	/*
 	 * Now go through the entire mask until we find a valid
 	 * target.
 	 */
-	do {
-		/*
-		 * We re-check online as the fallback case passes us
-		 * an untested affinity mask
-		 */
+	for_each_cpu_wrap(cpu, mask, first) {
 		if (cpu_online(cpu) && xive_try_pick_target(cpu))
 			return cpu;
-		cpu = cpumask_next(cpu, mask);
-		/* Wrap around */
-		if (cpu >= nr_cpu_ids)
-			cpu = cpumask_first(mask);
-	} while (cpu != first);
+	}
 
 	return -1;
 }
-- 
2.43.0