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Groups > linux.kernel > #1581433
| From | Christian Borntraeger <borntraeger@de.ibm.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [RFC] kasan stack overflow warnings again: READ_ONCE(), typecheck() |
| Date | 2017-02-15 17:30 +0100 |
| Message-ID | <tbaCS-2in-3@gated-at.bofh.it> (permalink) |
| References | <taUoq-8bx-17@gated-at.bofh.it> <tbaCR-2in-1@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 02/15/2017 05:18 PM, Christian Borntraeger wrote:
> On 02/15/2017 12:03 AM, Arnd Bergmann wrote:
>>
>> -#define WRITE_ONCE(x, val) \
>> -({ \
>> - union { typeof(x) __val; char __c[1]; } __u = \
>> - { .__val = (__force typeof(x)) (val) }; \
>> - __write_once_size(&(x), __u.__c, sizeof(x)); \
>> - __u.__val; \
>> -})
>> +#define WRITE_ONCE(x, val) \
>> +( \
>> + __builtin_choose_expr(sizeof(x) == 1, *(volatile typeof(&(x)))&(x) = (val), \
>> + __builtin_choose_expr(sizeof(x) == 2, *(volatile typeof(&(x)))&(x) = (val), \
>> + __builtin_choose_expr(sizeof(x) == 4, *(volatile typeof(&(x)))&(x) = (val), \
>> + __builtin_choose_expr(sizeof(x) == sizeof(long), *(volatile typeof(&(x)))&(x) = (val), \
>
> Have you run sparse on those changes?
> IIRC we had to add the __force to get rid of address space annotations
> in that macro above. Cannot tell if we need something like that here.
>
The original warning was
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>
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[RFC] kasan stack overflow warnings again: READ_ONCE(), typecheck() Arnd Bergmann <arnd@arndb.de> - 2017-02-15 00:10 +0100
Re: [RFC] kasan stack overflow warnings again: READ_ONCE(), typecheck() Dmitry Vyukov <dvyukov@google.com> - 2017-02-15 10:20 +0100
Re: [RFC] kasan stack overflow warnings again: READ_ONCE(), typecheck() Arnd Bergmann <arnd@arndb.de> - 2017-02-15 11:40 +0100
Re: [RFC] kasan stack overflow warnings again: READ_ONCE(), typecheck() Arnd Bergmann <arnd@arndb.de> - 2017-02-15 23:40 +0100
Re: [RFC] kasan stack overflow warnings again: READ_ONCE(), typecheck() Christian Borntraeger <borntraeger@de.ibm.com> - 2017-02-15 17:30 +0100
Re: [RFC] kasan stack overflow warnings again: READ_ONCE(), typecheck() Christian Borntraeger <borntraeger@de.ibm.com> - 2017-02-15 17:30 +0100
Re: [RFC] kasan stack overflow warnings again: READ_ONCE(), typecheck() Arnd Bergmann <arnd@arndb.de> - 2017-02-15 23:20 +0100
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