linux-kernel - [PATCH v2 2/4] mm/vmalloc: remove the redundant boundary check

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Message-Id: <20220607105958.382076-3-bhe@redhat.com>
Date:   Tue,  7 Jun 2022 18:59:56 +0800
From:   Baoquan He <bhe@...hat.com>
To:     akpm@...ux-foundation.org, urezki@...il.com
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        hch@...radead.org, Baoquan He <bhe@...hat.com>
Subject: [PATCH v2 2/4] mm/vmalloc: remove the redundant boundary check

In function find_va_links(), when traversing the vmap_area tree, the
comparing to check if the passed in 'va' is above or below 'tmp_va'
is redundant, assuming both 'va' and 'tmp_va' has ->va_start <= ->va_end.

Here, to simplify the checking as code change.

Signed-off-by: Baoquan He <bhe@...hat.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@...il.com>
---
 mm/vmalloc.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index f9d45aa90b7c..b711bf82fd5d 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -874,11 +874,9 @@ find_va_links(struct vmap_area *va,
 		 * Trigger the BUG() if there are sides(left/right)
 		 * or full overlaps.
 		 */
-		if (va->va_start < tmp_va->va_end &&
-				va->va_end <= tmp_va->va_start)
+		if (va->va_end <= tmp_va->va_start)
 			link = &(*link)->rb_left;
-		else if (va->va_end > tmp_va->va_start &&
-				va->va_start >= tmp_va->va_end)
+		else if (va->va_start >= tmp_va->va_end)
 			link = &(*link)->rb_right;
 		else {
 			WARN(1, "vmalloc bug: 0x%lx-0x%lx overlaps with 0x%lx-0x%lx\n",
-- 
2.34.1