netdev - [patch 1/1] cxgb4: drop __GFP

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Date:	Tue, 14 Apr 2015 13:24:33 -0700
From:	akpm@...ux-foundation.org
To:	hariprasad@...lsio.com, netdev@...r.kernel.org,
	akpm@...ux-foundation.org, mhocko@...e.cz, davem@...emloft.net,
	david@...morbit.com, hannes@...xchg.org, jack@...e.cz,
	mgorman@...e.de, penguin-kernel@...ove.SAKURA.ne.jp,
	rientjes@...gle.com, tytso@....edu
Subject: [patch 1/1] cxgb4: drop __GFP_NOFAIL allocation

From: Michal Hocko <mhocko@...e.cz>
Subject: cxgb4: drop __GFP_NOFAIL allocation

set_filter_wr is requesting __GFP_NOFAIL allocation although it can return
ENOMEM without any problems obviously (t4_l2t_set_switching does that
already).  So the non-failing requirement is too strong without any
obvious reason.  Drop __GFP_NOFAIL and reorganize the code to have the
failure paths easier.

The same applies to _c4iw_write_mem_dma_aligned which uses __GFP_NOFAIL
and then checks the return value and returns -ENOMEM on failure.  This
doesn't make any sense what so ever.  Either the allocation cannot fail or
it can.

del_filter_wr seems to be safe as well because the filter entry is not
marked as pending and the return value is propagated up the stack up to
c4iw_destroy_listen.

Signed-off-by: Michal Hocko <mhocko@...e.cz>
Cc: David Rientjes <rientjes@...gle.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Dave Chinner <david@...morbit.com>
Cc: "Theodore Ts'o" <tytso@....edu>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Cc: "David S. Miller" <davem@...emloft.net>
Cc: Hariprasad S <hariprasad@...lsio.com>
Cc: Jan Kara <jack@...e.cz>
Cc: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---

 drivers/infiniband/hw/cxgb4/mem.c               |    2 -
 drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c |   15 +++++++++++---
 2 files changed, 13 insertions(+), 4 deletions(-)

diff -puN drivers/infiniband/hw/cxgb4/mem.c~cxgb4-drop-__gfp_nofail-allocation drivers/infiniband/hw/cxgb4/mem.c
--- a/drivers/infiniband/hw/cxgb4/mem.c~cxgb4-drop-__gfp_nofail-allocation
+++ a/drivers/infiniband/hw/cxgb4/mem.c
@@ -73,7 +73,7 @@ static int _c4iw_write_mem_dma_aligned(s
 		c4iw_init_wr_wait(&wr_wait);
 	wr_len = roundup(sizeof(*req) + sizeof(*sgl), 16);
 
-	skb = alloc_skb(wr_len, GFP_KERNEL | __GFP_NOFAIL);
+	skb = alloc_skb(wr_len, GFP_KERNEL);
 	if (!skb)
 		return -ENOMEM;
 	set_wr_txq(skb, CPL_PRIORITY_CONTROL, 0);
diff -puN drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c~cxgb4-drop-__gfp_nofail-allocation drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c
--- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c~cxgb4-drop-__gfp_nofail-allocation
+++ a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c
@@ -1149,6 +1149,10 @@ static int set_filter_wr(struct adapter
 	struct fw_filter_wr *fwr;
 	unsigned int ftid;
 
+	skb = alloc_skb(sizeof(*fwr), GFP_KERNEL);
+	if (!skb)
+		return -ENOMEM;
+
 	/* If the new filter requires loopback Destination MAC and/or VLAN
 	 * rewriting then we need to allocate a Layer 2 Table (L2T) entry for
 	 * the filter.
@@ -1156,19 +1160,21 @@ static int set_filter_wr(struct adapter
 	if (f->fs.newdmac || f->fs.newvlan) {
 		/* allocate L2T entry for new filter */
 		f->l2t = t4_l2t_alloc_switching(adapter->l2t);
-		if (f->l2t == NULL)
+		if (f->l2t == NULL) {
+			kfree_skb(skb);
 			return -EAGAIN;
+		}
 		if (t4_l2t_set_switching(adapter, f->l2t, f->fs.vlan,
 					f->fs.eport, f->fs.dmac)) {
 			cxgb4_l2t_release(f->l2t);
 			f->l2t = NULL;
+			kfree_skb(skb);
 			return -ENOMEM;
 		}
 	}
 
 	ftid = adapter->tids.ftid_base + fidx;
 
-	skb = alloc_skb(sizeof(*fwr), GFP_KERNEL | __GFP_NOFAIL);
 	fwr = (struct fw_filter_wr *)__skb_put(skb, sizeof(*fwr));
 	memset(fwr, 0, sizeof(*fwr));
 
@@ -1266,7 +1272,10 @@ static int del_filter_wr(struct adapter
 	len = sizeof(*fwr);
 	ftid = adapter->tids.ftid_base + fidx;
 
-	skb = alloc_skb(len, GFP_KERNEL | __GFP_NOFAIL);
+	skb = alloc_skb(len, GFP_KERNEL);
+	if (!skb)
+		return -ENOMEM;
+
 	fwr = (struct fw_filter_wr *)__skb_put(skb, len);
 	t4_mk_filtdelwr(ftid, fwr, adapter->sge.fw_evtq.abs_id);
 
_
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