linux-kernel - [PATCH] powerpc: remove unneeded check in spu_gang_remove

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Date:	Mon, 22 Jun 2015 21:49:11 +0300
From:	Yury Norov <yury.norov@...il.com>
To:	arnd@...db.de, benh@...nel.crashing.org, paulus@...ba.org
Cc:	linuxppc-dev@...ts.ozlabs.org, cbe-oss-dev@...ts.ozlabs.org,
	linux-kernel@...r.kernel.org, klimov.linux@...il.com,
	Yury Norov <yury.norov@...il.com>
Subject: [PATCH] powerpc: remove unneeded check in spu_gang_remove_ctx

In discussion to patch "selinux: reduce locking overhead in
inode_free_security()" it was figured out that list_del_init()
is safe to be called multiple times on the same entry. In that
case, it was useful to move a check out of spinlock to decrease
lock contention. Here we can remove '!list_empty()' check completely
and decrease 'spu_gang_remove_ctx()' function size, and (sometimes)
avoid branch predictor misses.

Signed-off-by: Yury Norov <yury.norov@...il.com>
---
 arch/powerpc/platforms/cell/spufs/gang.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/platforms/cell/spufs/gang.c b/arch/powerpc/platforms/cell/spufs/gang.c
index 71a4432..67e3fc3 100644
--- a/arch/powerpc/platforms/cell/spufs/gang.c
+++ b/arch/powerpc/platforms/cell/spufs/gang.c
@@ -75,10 +75,10 @@ void spu_gang_remove_ctx(struct spu_gang *gang, struct spu_context *ctx)
 {
 	mutex_lock(&gang->mutex);
 	WARN_ON(ctx->gang != gang);
-	if (!list_empty(&ctx->aff_list)) {
-		list_del_init(&ctx->aff_list);
-		gang->aff_flags &= ~AFF_OFFSETS_SET;
-	}
+
+	list_del_init(&ctx->aff_list);
+	gang->aff_flags &= ~AFF_OFFSETS_SET;
+
 	list_del_init(&ctx->gang_list);
 	gang->contexts--;
 	mutex_unlock(&gang->mutex);
-- 
2.1.4

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