linux-kernel - [PATCH] xen: avoid type warning in xchg_xen

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Message-Id: <20170529130125.307182-1-arnd@arndb.de>
Date:   Mon, 29 May 2017 15:01:14 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Stefano Stabellini <sstabellini@...nel.org>
Cc:     Arnd Bergmann <arnd@...db.de>, Ian Abbott <abbotti@....co.uk>,
        xen-devel@...ts.xenproject.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] xen: avoid type warning in xchg_xen_ulong

The improved type-checking version of container_of() triggers a warning for
xchg_xen_ulong, pointing out that 'xen_ulong_t' is unsigned, but atomic64_t
contains a signed value:

drivers/xen/events/events_2l.c: In function 'evtchn_2l_handle_events':
arch/x86/include/asm/cmpxchg.h:87:21: error: 'pending_words' is used uninitialized in this function [-Werror=uninitialized]

This adds a cast to work around the warning

Cc: Ian Abbott <abbotti@....co.uk>
Fixes: 85323a991d40 ("xen: arm: mandate EABI and use generic atomic operations.")
Fixes: daa2ac80834d ("kernel.h: handle pointers to arrays better in container_of()")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 arch/arm/include/asm/xen/events.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/xen/events.h b/arch/arm/include/asm/xen/events.h
index 71e473d05fcc..620dc75362e5 100644
--- a/arch/arm/include/asm/xen/events.h
+++ b/arch/arm/include/asm/xen/events.h
@@ -16,7 +16,7 @@ static inline int xen_irqs_disabled(struct pt_regs *regs)
 	return raw_irqs_disabled_flags(regs->ARM_cpsr);
 }
 
-#define xchg_xen_ulong(ptr, val) atomic64_xchg(container_of((ptr),	\
+#define xchg_xen_ulong(ptr, val) atomic64_xchg(container_of((long long*)(ptr),\
 							    atomic64_t,	\
 							    counter), (val))
 
-- 
2.9.0