linux-kernel - [PATCH] userns: simplify map_id_range

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Date:	Sun, 26 Jul 2015 09:50:32 +0800
From:	Nicolas Iooss <nicolas.iooss_linux@....org>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Andy Lutomirski <luto@...capital.net>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org,
	Nicolas Iooss <nicolas.iooss_linux@....org>
Subject: [PATCH] userns: simplify map_id_range_* functions

Functions map_id_range_down, map_id_down and map_id_up all used the
construction:

    if (...)
        id = ...
    else
        id = ...
    return id;

which can be simplified by directly returning the result of the
computations in each branch.

Moreover as the condition tested whether the "break;" in the previous
for loop was hit, it is simpler to directly compute the result and
return it.

Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@....org>
---

As I could not find any relevant entry for kernel/user_namespace.c in
MAINTAINERS, I have built the list of recipients from the git history.
Please let me know if I was expected to proceed differently to submit
this patch.

 kernel/user_namespace.c | 31 +++++++------------------------
 1 file changed, 7 insertions(+), 24 deletions(-)

diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 4109f8320684..bf063dc6b8d4 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -165,15 +165,10 @@ static u32 map_id_range_down(struct uid_gid_map *map, u32 id, u32 count)
 		last = first + map->extent[idx].count - 1;
 		if (id >= first && id <= last &&
 		    (id2 >= first && id2 <= last))
-			break;
+			return (id - first) + map->extent[idx].lower_first;
 	}
-	/* Map the id or note failure */
-	if (idx < extents)
-		id = (id - first) + map->extent[idx].lower_first;
-	else
-		id = (u32) -1;
-
-	return id;
+	/* Note failure */
+	return (u32) -1;
 }
 
 static u32 map_id_down(struct uid_gid_map *map, u32 id)
@@ -188,15 +183,9 @@ static u32 map_id_down(struct uid_gid_map *map, u32 id)
 		first = map->extent[idx].first;
 		last = first + map->extent[idx].count - 1;
 		if (id >= first && id <= last)
-			break;
+			return (id - first) + map->extent[idx].lower_first;
 	}
-	/* Map the id or note failure */
-	if (idx < extents)
-		id = (id - first) + map->extent[idx].lower_first;
-	else
-		id = (u32) -1;
-
-	return id;
+	return (u32) -1;
 }
 
 static u32 map_id_up(struct uid_gid_map *map, u32 id)
@@ -211,15 +200,9 @@ static u32 map_id_up(struct uid_gid_map *map, u32 id)
 		first = map->extent[idx].lower_first;
 		last = first + map->extent[idx].count - 1;
 		if (id >= first && id <= last)
-			break;
+			return (id - first) + map->extent[idx].first;
 	}
-	/* Map the id or note failure */
-	if (idx < extents)
-		id = (id - first) + map->extent[idx].first;
-	else
-		id = (u32) -1;
-
-	return id;
+	return (u32) -1;
 }
 
 /**
-- 
2.4.6

--
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