From: anton.ivanov@cambridgegreys.com
To: linux-um@lists.infradead.org
Cc: richard@nod.at, Anton Ivanov <anton.ivanov@cambridgegreys.com>
Subject: [PATCH v4 6/7] um: swithch futex ops to cmpxchg
Date: Fri, 11 Dec 2020 17:45:58 +0000 [thread overview]
Message-ID: <20201211174559.26010-7-anton.ivanov@cambridgegreys.com> (raw)
In-Reply-To: <20201211174559.26010-1-anton.ivanov@cambridgegreys.com>
From: Anton Ivanov <anton.ivanov@cambridgegreys.com>
As a result of switching from emulated to true atomic cmpxchg
we can use cmpxchg in the corresponding um futex op.
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
---
arch/um/kernel/skas/uaccess.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/arch/um/kernel/skas/uaccess.c b/arch/um/kernel/skas/uaccess.c
index de71048b5371..858b2e16e364 100644
--- a/arch/um/kernel/skas/uaccess.c
+++ b/arch/um/kernel/skas/uaccess.c
@@ -343,7 +343,6 @@ EXPORT_SYMBOL(arch_futex_atomic_op_inuser);
* -EAGAIN - Atomic operation was unable to complete due to contention
* -ENOSYS - Function not implemented (only if !HAVE_FUTEX_CMPXCHG)
*/
-
int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
u32 oldval, u32 newval)
{
@@ -366,8 +365,7 @@ int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
val = *uaddr;
- if (val == oldval)
- *uaddr = newval;
+ ret = cmpxchg(uaddr, oldval, newval);
*uval = val;
pagefault_enable();
--
2.20.1
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next prev parent reply other threads:[~2020-12-11 17:46 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-11 17:45 Amended and retested for 32 bit "borrow ops" series anton.ivanov
2020-12-11 17:45 ` [PATCH v4 1/7] um: allow the use of glibc functions instead of builtins anton.ivanov
2020-12-11 20:03 ` Johannes Berg
2020-12-11 17:45 ` [PATCH v4 2/7] um: enable the use of optimized xor routines in UML anton.ivanov
2020-12-11 20:07 ` Johannes Berg
2020-12-11 21:57 ` Anton Ivanov
2020-12-11 22:00 ` Johannes Berg
2020-12-11 22:40 ` Anton Ivanov
2020-12-14 9:07 ` Anton Ivanov
2020-12-14 9:12 ` Johannes Berg
2020-12-14 9:36 ` Anton Ivanov
2020-12-11 17:45 ` [PATCH v4 3/7] um: "borrow" atomics from x86 architecture anton.ivanov
2020-12-11 20:08 ` Johannes Berg
2020-12-11 21:31 ` Anton Ivanov
2020-12-11 17:45 ` [PATCH v4 4/7] um: add a UML specific futex implementation anton.ivanov
2020-12-11 20:10 ` Johannes Berg
2020-12-11 17:45 ` [PATCH v4 5/7] um: "borrow" cmpxchg from x86 tree in UML anton.ivanov
2020-12-11 17:45 ` anton.ivanov [this message]
2020-12-11 20:12 ` [PATCH v4 6/7] um: swithch futex ops to cmpxchg Johannes Berg
2020-12-11 21:33 ` Anton Ivanov
2020-12-11 17:45 ` [PATCH v4 7/7] um: borrow bitops from the x86 tree anton.ivanov
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