Commit-ID: ba33034fffc1189d95301bd865f1c799256e72a2
Gitweb: http://git.kernel.org/tip/ba33034fffc1189d95301bd865f1c799256e72a2
Author: Christian Borntraeger <[email protected]>
AuthorDate: Tue, 4 Aug 2015 09:55:48 +0200
Committer: Ingo Molnar <[email protected]>
CommitDate: Wed, 12 Aug 2015 11:58:58 +0200
locking, compiler.h: Cast away attributes in the WRITE_ONCE() magic
The kernel build bot showed a new warning triggered by commit:
76695af20c01 ("locking, arch: use WRITE_ONCE()/READ_ONCE() in
smp_store_release()/smp_load_acquire()")
because Sparse does not like WRITE_ONCE() accessing elements
from the (sparse) RCU address space:
fs/afs/inode.c:448:9: sparse: incorrect type in initializer (different
address spaces)
fs/afs/inode.c:448:9: expected struct afs_permits *__val
fs/afs/inode.c:448:9: got void [noderef] <asn:4>*<noident>
Solution is to force cast away the sparse attributes for the initializer
of the union in WRITE_ONCE().
(And as this now gets too long, also split the macro into multiple lines.)
Signed-off-by: Christian Borntraeger <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Paul McKenney <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link:
http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
include/linux/compiler.h | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index e08a6ae..c836eb2 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -252,7 +252,12 @@ static __always_inline void __write_once_size(volatile
void *p, void *res, int s
({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x),
__u.__c, sizeof(x)); __u.__val; })
#define WRITE_ONCE(x, val) \
- ({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) };
__write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
+({ \
+ union { typeof(x) __val; char __c[1]; } __u = \
+ { .__val = (__force typeof(x)) (val) }; \
+ __write_once_size(&(x), __u.__c, sizeof(x)); \
+ __u.__val; \
+})
/**
* READ_ONCE_CTRL - Read a value heading a control dependency
--
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