linux-kernel - [PATCH 3/3] drivers/misc/sgi-gru: fix return of error

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Date:	Mon, 21 Sep 2015 15:48:19 +0530
From:	Sudip Mukherjee <sudipm.mukherjee@...il.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Arnd Bergmann <arnd@...db.de>,
	Dimitri Sivanich <sivanich@....com>
Cc:	linux-kernel@...r.kernel.org,
	Sudip Mukherjee <sudipm.mukherjee@...il.com>
Subject: [PATCH 3/3] drivers/misc/sgi-gru: fix return of error

If kzalloc() fails then gms is NULL and we are returning NULL, but the
functions which called this function gru_register_mmu_notifier() are not
expecting NULL as the return. They are expecting either a valid pointer
or the error code in ERR_PTR.

Signed-off-by: Sudip Mukherjee <sudip@...torindia.org>
---

The patch at https://patchwork.kernel.org/patch/6394911/ is not applied
and not relevant now as gms is checked before gru_dbg. But the idea for
this patch was obtained from that one.

 drivers/misc/sgi-gru/grutlbpurge.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/misc/sgi-gru/grutlbpurge.c b/drivers/misc/sgi-gru/grutlbpurge.c
index 757a8e9..e936d43 100644
--- a/drivers/misc/sgi-gru/grutlbpurge.c
+++ b/drivers/misc/sgi-gru/grutlbpurge.c
@@ -306,16 +306,16 @@ struct gru_mm_struct *gru_register_mmu_notifier(void)
 		atomic_inc(&gms->ms_refcnt);
 	} else {
 		gms = kzalloc(sizeof(*gms), GFP_KERNEL);
-		if (gms) {
-			STAT(gms_alloc);
-			spin_lock_init(&gms->ms_asid_lock);
-			gms->ms_notifier.ops = &gru_mmuops;
-			atomic_set(&gms->ms_refcnt, 1);
-			init_waitqueue_head(&gms->ms_wait_queue);
-			err = __mmu_notifier_register(&gms->ms_notifier, current->mm);
-			if (err)
-				goto error;
-		}
+		if (!gms)
+			return ERR_PTR(-ENOMEM);
+		STAT(gms_alloc);
+		spin_lock_init(&gms->ms_asid_lock);
+		gms->ms_notifier.ops = &gru_mmuops;
+		atomic_set(&gms->ms_refcnt, 1);
+		init_waitqueue_head(&gms->ms_wait_queue);
+		err = __mmu_notifier_register(&gms->ms_notifier, current->mm);
+		if (err)
+			goto error;
 	}
 	if (gms)
 		gru_dbg(grudev, "gms %p, refcnt %d\n", gms,
-- 
1.9.1

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