From: Bob Liu <bob.liu@oracle.com>
Date: Fri, 2 May 2014 09:46:09 +0000 (+0200)
Subject: tmem: drop unnecessary lock in tmem_relinquish_pages()
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~5118
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=427f62f1804efb0c0ddd0c14b1ca8661292f8b70;p=xen.git

tmem: drop unnecessary lock in tmem_relinquish_pages()

CID 1150562

tmem_rwlock is unnecessary in tmem_relinquish_pages(), as
such lock is used as gate for hypercalls. However
tmem_relinquish_pages deals with pages that are no longer
owned by any domain - hence there is no need for tmem_rwlock.

Also the function is protected by the 'heap_lock' which
is the only calleer of this function.

This patch drops said lock.

Signed-off-by: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---

diff --git a/xen/common/tmem.c b/xen/common/tmem.c
index f7f828f11c..f2dc26e173 100644
--- a/xen/common/tmem.c
+++ b/xen/common/tmem.c
@@ -2794,9 +2794,6 @@ void *tmem_relinquish_pages(unsigned int order, unsigned int memflags)
         return NULL;
     }
 
-    if ( memflags & MEMF_tmem )
-        read_lock(&tmem_rwlock);
-
     while ( (pfp = tmem_page_list_get()) == NULL )
     {
         if ( (max_evictions-- <= 0) || !tmem_evict())
@@ -2812,9 +2809,6 @@ void *tmem_relinquish_pages(unsigned int order, unsigned int memflags)
         relinq_pgs++;
     }
 
-    if ( memflags & MEMF_tmem )
-        read_unlock(&tmem_rwlock);
-
     return pfp;
 }