linux-kernel - [PATCH] infiniband, ipath: convert old cpumask api into new one

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Date:	Thu, 19 May 2011 10:04:42 +0900
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	roland@...nel.org, sean.hefty@...el.com, hal.rosenstock@...il.com,
	linux-rdma@...r.kernel.org, infinipath@...gic.com,
	linux-kernel@...r.kernel.org
CC:	kosaki.motohiro@...fujitsu.com
Subject: [PATCH] infiniband, ipath: convert old cpumask api into new one

Adapt new api. we plan to remove old one later. Almost change are
trivial. but there is one real fix. following code is unsafe.

	int ncpus = num_online_cpus()
	for (i = 0; i < ncpus; i++) {
		..
	}

because 1) we don't guarantee last bit of online cpus is equal
to num_online_cpus(). some arch assign sparse cpu number.
2) cpu hotplugging may change cpu_online_mask at same time.
we need to pin it by get_online_cpus().

Cc: Roland Dreier <roland@...nel.org>
Cc: Sean Hefty <sean.hefty@...el.com>
Cc: Hal Rosenstock <hal.rosenstock@...il.com>
Cc: linux-rdma@...r.kernel.org
Cc: Ralph Campbell <infinipath@...gic.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
---
 drivers/infiniband/hw/ipath/ipath_file_ops.c |   11 +++++++----
 1 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/infiniband/hw/ipath/ipath_file_ops.c b/drivers/infiniband/hw/ipath/ipath_file_ops.c
index bdf4422..aab5d89 100644
--- a/drivers/infiniband/hw/ipath/ipath_file_ops.c
+++ b/drivers/infiniband/hw/ipath/ipath_file_ops.c
@@ -40,6 +40,7 @@
 #include <linux/highmem.h>
 #include <linux/io.h>
 #include <linux/jiffies.h>
+#include <linux/cpu.h>
 #include <asm/pgtable.h>

 #include "ipath_kernel.h"
@@ -1684,17 +1685,19 @@ static int find_best_unit(struct file *fp,
 	 * information.  There may be some issues with dual core numbering
 	 * as well.  This needs more work prior to release.
 	 */
-	if (!cpumask_empty(&current->cpus_allowed) &&
-	    !cpumask_full(&current->cpus_allowed)) {
+	if (!cpumask_empty(tsk_cpus_allowed(current)) &&
+	    !cpumask_full(tsk_cpus_allowed(current))) {
 		int ncpus = num_online_cpus(), curcpu = -1, nset = 0;
-		for (i = 0; i < ncpus; i++)
-			if (cpumask_test_cpu(i, &current->cpus_allowed)) {
+		get_online_cpus();
+		for_each_online_cpu(i)
+			if (cpumask_test_cpu(i, tsk_cpus_allowed(current))) {
 				ipath_cdbg(PROC, "%s[%u] affinity set for "
 					   "cpu %d/%d\n", current->comm,
 					   current->pid, i, ncpus);
 				curcpu = i;
 				nset++;
 			}
+		put_online_cpus();
 		if (curcpu != -1 && nset != ncpus) {
 			if (npresent) {
 				prefunit = curcpu / (ncpus / npresent);
-- 
1.7.3.1


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