lkml.org 
[lkml]   [2015]   [Nov]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] xen/time: use READ_ONCE
Date
Use READ_ONCE through the code, rather than explicit barriers.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
CC: Mark Rutland <mark.rutland@arm.com>
CC: konrad.wilk@oracle.com
CC: david.vrabel@citrix.com
CC: boris.ostrovsky@oracle.com
---
drivers/xen/time.c | 17 +++++++----------
1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/drivers/xen/time.c b/drivers/xen/time.c
index 433fe24..7107842 100644
--- a/drivers/xen/time.c
+++ b/drivers/xen/time.c
@@ -25,7 +25,7 @@ static u64 get64(const u64 *p)

if (BITS_PER_LONG < 64) {
u32 *p32 = (u32 *)p;
- u32 h, l;
+ u32 h, l, h2;

/*
* Read high then low, and then make sure high is
@@ -34,15 +34,14 @@ static u64 get64(const u64 *p)
* XXX some clean way to make this endian-proof?
*/
do {
- h = p32[1];
- barrier();
- l = p32[0];
- barrier();
- } while (p32[1] != h);
+ h = READ_ONCE(p32[1]);
+ l = READ_ONCE(p32[0]);
+ h2 = READ_ONCE(p32[1]);
+ } while(h2 != h);

ret = (((u64)h) << 32) | l;
} else
- ret = *p;
+ ret = READ_ONCE(*p);

return ret;
}
@@ -66,9 +65,7 @@ void xen_get_runstate_snapshot(struct vcpu_runstate_info *res)
*/
do {
state_time = get64(&state->state_entry_time);
- barrier();
- *res = *state;
- barrier();
+ *res = READ_ONCE(*state);
} while (get64(&state->state_entry_time) != state_time);
}

--
1.7.10.4


\
 
 \ /
  Last update: 2015-11-20 16:21    [W:1.173 / U:0.108 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site