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locking/qspinlock: Pull in asm/byteorder.h to ensure correct endianness
This commit is not required upstream, but is required for the 4.9.y
stable series.
Upstream commit 101110f627
("Kbuild: always define endianess in
kconfig.h") ensures that either __LITTLE_ENDIAN or __BIG_ENDIAN is
defined to reflect the endianness of the target CPU architecture
regardless of whether or not <asm/byteorder.h> has been #included. The
upstream definition of 'struct qspinlock' relies on this property.
Unfortunately, the 4.9.y stable series does not provide this guarantee,
so the 'spin_unlock()' routine can erroneously treat the underlying
lockword as big-endian on little-endian architectures using native
qspinlock (i.e. x86_64 without PV) if the caller has not included
<asm/byteorder.h>. This can lead to hangs such as the one in
'i915_gem_request()' reported via bugzilla:
https://bugzilla.kernel.org/show_bug.cgi?id=202063
Fix the issue by ensuring that <asm/byteorder.h> is #included in
<asm/qspinlock_types.h>, where 'struct qspinlock' is defined.
Cc: <stable@vger.kernel.org> # 4.9
Signed-off-by: Dave Airlie <airlied@redhat.com>
[will: wrote commit message]
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -18,6 +18,8 @@
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#ifndef __ASM_GENERIC_QSPINLOCK_TYPES_H
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#define __ASM_GENERIC_QSPINLOCK_TYPES_H
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#include <asm/byteorder.h>
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/*
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* Including atomic.h with PARAVIRT on will cause compilation errors because
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* of recursive header file incluson via paravirt_types.h. So don't include
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