From 4b527f25a4ac64c0d17c882cdf8322be66f31611 Mon Sep 17 00:00:00 2001 From: Dave Airlie Date: Thu, 24 Jan 2019 18:54:15 +0000 Subject: [PATCH] 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 101110f6271c ("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 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 . 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 is #included in , where 'struct qspinlock' is defined. Cc: # 4.9 Signed-off-by: Dave Airlie [will: wrote commit message] Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman --- include/asm-generic/qspinlock_types.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/include/asm-generic/qspinlock_types.h b/include/asm-generic/qspinlock_types.h index d10f1e7d6ba8..6503e96710fa 100644 --- a/include/asm-generic/qspinlock_types.h +++ b/include/asm-generic/qspinlock_types.h @@ -18,6 +18,8 @@ #ifndef __ASM_GENERIC_QSPINLOCK_TYPES_H #define __ASM_GENERIC_QSPINLOCK_TYPES_H +#include + /* * Including atomic.h with PARAVIRT on will cause compilation errors because * of recursive header file incluson via paravirt_types.h. So don't include