UPSTREAM: kernel: make READ_ONCE() valid on const arguments
The use of READ_ONCE() causes lots of warnings witht he pending paravirt
spinlock fixes, because those ends up having passing a member to a
'const' structure to READ_ONCE().
There should certainly be nothing wrong with using READ_ONCE() with a
const source, but the helper function __read_once_size() would cause
warnings because it would drop the 'const' qualifier, but also because
the destination would be marked 'const' too due to the use of 'typeof'.
Use a union of types in READ_ONCE() to avoid this issue.
Also make sure to use parenthesis around the macro arguments to avoid
possible operator precedence issues.
Tested-by: Ingo Molnar <mingo@kernel.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Issue: SEC-1289
Bug: 28705983
(cherry picked from commit dd36929720f40f17685e841ae0d4c581c165ea60)
Change-Id: I73b280cfae42245f6adf6a8e50be7f9177c88ebe
(cherry picked from commit 20a8b65f6540fa3088a256d8067c441f1f178b8e)
1 file changed