linux-kernel - [PATCH v2 1/4] lib/rhashtable: simplify bucket_table

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Message-ID: <20180622181540.5gul4lx5dteqzzk3@linux-r8p5>
Date:   Fri, 22 Jun 2018 11:15:40 -0700
From:   Davidlohr Bueso <dave@...olabs.net>
To:     akpm@...ux-foundation.org, torvalds@...ux-foundation.org
Cc:     tgraf@...g.ch, herbert@...dor.apana.org.au,
        manfred@...orfullife.com, mhocko@...nel.org,
        guillaume.knispel@...ersonicimagine.com, linux-api@...r.kernel.org,
        linux-kernel@...r.kernel.org, Davidlohr Bueso <dbueso@...e.de>
Subject: [PATCH v2 1/4] lib/rhashtable: simplify bucket_table_alloc()

As of ce91f6ee5b3 (mm: kvmalloc does not fallback to vmalloc for incompatible gfp flag),
we can simplify the caller and trust kvzalloc() to just do the right thing. For the
case of the GFP_ATOMIC context, we can drop the __GFP_NORETRY flag for obvious reasons,
and for the __GFP_NOWARN case, however, it is changed such that the caller passes the
flag instead of making bucket_table_alloc() handle it.

This slightly changes the gfp flags passed on to nested_table_alloc() as it will now
also use GFP_ATOMIC | __GFP_NOWARN. However, I consider this a positive consequence
as for the same reasons we want nowarn semantics in bucket_table_alloc().

Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
---

v2:
- Changes based on Neil's concerns about keeping nowarn flag.
- Better changelog.

 lib/rhashtable.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 9427b5766134..083f871491a1 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -175,10 +175,7 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
 	int i;

 	size = sizeof(*tbl) + nbuckets * sizeof(tbl->buckets[0]);
-	if (gfp != GFP_KERNEL)
-		tbl = kzalloc(size, gfp | __GFP_NOWARN | __GFP_NORETRY);
-	else
-		tbl = kvzalloc(size, gfp);
+	tbl = kvzalloc(size, gfp);

 	size = nbuckets;

@@ -459,7 +456,7 @@ static int rhashtable_insert_rehash(struct rhashtable *ht,

 	err = -ENOMEM;

-	new_tbl = bucket_table_alloc(ht, size, GFP_ATOMIC);
+	new_tbl = bucket_table_alloc(ht, size, GFP_ATOMIC | __GFP_NOWARN);
 	if (new_tbl == NULL)
 		goto fail;

-- 
2.16.4