linux-kernel - [PATCH v2 12/61] xen/privcmd: Optimized privcmd_ioctl_mmap() by using vma

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Message-ID: <20210817154651.1570984-13-Liam.Howlett@oracle.com>
Date:   Tue, 17 Aug 2021 15:47:12 +0000
From:   Liam Howlett <liam.howlett@...cle.com>
To:     "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
CC:     Song Liu <songliubraving@...com>,
        Davidlohr Bueso <dave@...olabs.net>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Matthew Wilcox <willy@...radead.org>,
        Laurent Dufour <ldufour@...ux.ibm.com>,
        David Rientjes <rientjes@...gle.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Rik van Riel <riel@...riel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Michel Lespinasse <walken.cr@...il.com>,
        Liam Howlett <liam.howlett@...cle.com>
Subject: [PATCH v2 12/61] xen/privcmd: Optimized privcmd_ioctl_mmap() by using
 vma_lookup()

From: "Liam R. Howlett" <Liam.Howlett@...cle.com>

vma_lookup() walks the VMA tree for a specific value, find_vma() will
search the tree after walking to a specific value.  It is more efficient
to only walk to the requested value as this case requires the address to
equal the vm_start.

Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 drivers/xen/privcmd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index 720a7b7abd46..5f903ae9af7e 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -282,7 +282,7 @@ static long privcmd_ioctl_mmap(struct file *file, void __user *udata)
 						     struct page, lru);
 		struct privcmd_mmap_entry *msg = page_address(page);
 
-		vma = find_vma(mm, msg->va);
+		vma = vma_lookup(mm, msg->va);
 		rc = -EINVAL;
 
 		if (!vma || (msg->va != vma->vm_start) || vma->vm_private_data)
-- 
2.30.2