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Problem: SIGBUS on SPARC64

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Solution: force the compiler to make the atomic_counter_t alignment
friendly.
This will ensure that the pointers inside the buffers allocated by
shared_message_memory are aligned, at the cost of growing the memory
size of atomic_counter_t from 4 to 8 bytes on 64 bit (when not using
mutexes).
Note that although content_t contains an atomic_counter_t, the
compiler already padded the struct so there is no change in the
buffer sizes used by the engines, save for the extra 4 bytes for the
buffer's own single atomic counter.
Fixes #2588
This commit is contained in:
Luca Boccassi 2017-08-11 17:48:23 +01:00
parent f0ae5e585c
commit e376c81c2d
1 changed files with 20 additions and 0 deletions
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20
src/atomic_counter.hpp
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@ -69,8 +69,22 @@ namespace zmq
// This class represents an integer that can be incremented/decremented
// in atomic fashion.
//
// In zmq::shared_message_memory_allocator a buffer with an atomic_counter_t
// at the start is allocated. If the class does not align to pointer size,
// access to pointers in structures in the buffer will cause SIGBUS on
// architectures that do not allow mis-aligned pointers (eg: SPARC).
// Force the compiler to align to pointer size, which will cause the object
// to grow from 4 bytes to 8 bytes on 64 bit architectures (when not using
// mutexes).
#if defined (_MSC_VER) && (defined (_M_X64) || defined (_M_ARM64))
class __declspec (align (8)) atomic_counter_t
#elif defined (_MSC_VER) && (defined (_M_IX86) || defined (_M_ARM_ARMV7VE))
class __declspec (align (4)) atomic_counter_t
#else
class atomic_counter_t
#endif
{
public:
@ -212,7 +226,13 @@ namespace zmq
atomic_counter_t (const atomic_counter_t&);
const atomic_counter_t& operator = (const atomic_counter_t&);
#endif
#if defined (__GNUC__) || defined ( __INTEL_COMPILER) || \
(defined (__SUNPRO_C) && __SUNPRO_C >= 0x590) || \
(defined (__SUNPRO_CC) && __SUNPRO_CC >= 0x590)
} __attribute__ ((aligned (sizeof (void *))));
#else
};
#endif
}