From 25726f4269c742fd41ee0df733bbe7a3a05339ac Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Wed, 16 Aug 2017 10:56:23 +0200 Subject: [PATCH] gnttab: drop useless locking Holding any lock while accessing the maptrack entry fields is pointless, as these entries are protected by their associated active entry lock (which is being acquired later, before re-validating the fields read without holding the lock). Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper --- xen/common/grant_table.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c index 56082d8373..5e578c69ff 100644 --- a/xen/common/grant_table.c +++ b/xen/common/grant_table.c @@ -1143,19 +1143,14 @@ __gnttab_unmap_common( smp_rmb(); map = &maptrack_entry(lgt, op->handle); - grant_read_lock(lgt); - if ( unlikely(!read_atomic(&map->flags)) ) { - grant_read_unlock(lgt); gdprintk(XENLOG_INFO, "Zero flags for handle %#x\n", op->handle); op->status = GNTST_bad_handle; return; } dom = map->domid; - grant_read_unlock(lgt); - if ( unlikely((rd = rcu_lock_domain_by_id(dom)) == NULL) ) { /* This can happen when a grant is implicitly unmapped. */ -- 2.30.2