Arnd Bergmann 7322dd755e byteswap: try to avoid __builtin_constant_p gcc bug ... This is another attempt to avoid a regression in wwn_to_u64() after that started using get_unaligned_be64(), which in turn ran into a bug on gcc-4.9 through 6.1. The regression got introduced due to the combination of two separate workarounds (commits e3bde9568d: "include/linux/unaligned: force inlining of byteswap operations" and ef3fb2422f: "scsi: fc: use get/put_unaligned64 for wwn access") that each try to sidestep distinct problems with gcc behavior (code growth and increased stack usage). Unfortunately after both have been applied, a more serious gcc bug has been uncovered, leading to incorrect object code that discards part of a function and causes undefined behavior. As part of this problem is how __builtin_constant_p gets evaluated on an argument passed by reference into an inline function, this avoids the use of __builtin_constant_p() for all architectures that set CONFIG_ARCH_USE_BUILTIN_BSWAP. Most architectures do not set ARCH_SUPPORTS_OPTIMIZED_INLINING, which means they probably do not suffer from the problem in the qla2xxx driver, but they might still run into it elsewhere. Both of the original workarounds were only merged in the 4.6 kernel, and the bug that is fixed by this patch should only appear if both are there, so we probably don't need to backport the fix. On the other hand, it works by simplifying the code path and should not have any negative effects. [arnd@arndb.de: fix older gcc warnings] (http://lkml.kernel.org/r/12243652.bxSxEgjgfk@wuerfel) Link: https://lkml.org/lkml/headers/2016/4/12/1103 Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66122 Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70232 Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70646 Fixes: e3bde9568d ("include/linux/unaligned: force inlining of byteswap operations") Fixes: ef3fb2422f ("scsi: fc: use get/put_unaligned64 for wwn access") Link: http://lkml.kernel.org/r/1780465.XdtPJpi8Tt@wuerfel Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Tested-by: Josh Poimboeuf <jpoimboe@redhat.com> # on gcc-5.3 Tested-by: Quinn Tran <quinn.tran@qlogic.com> Cc: Martin Jambor <mjambor@suse.cz> Cc: "Martin K. Petersen" <martin.petersen@oracle.com> Cc: James Bottomley <James.Bottomley@hansenpartnership.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Thomas Graf <tgraf@suug.ch> Cc: Peter Zijlstra <peterz@infradead.org> Cc: David Rientjes <rientjes@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Himanshu Madhani <himanshu.madhani@qlogic.com> Cc: Jan Hubicka <hubicka@ucw.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2016-05-05 17:38:53 -07:00
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asm-generic	generic syscalls: wire up preadv2 and pwritev2 syscalls	2016-04-23 22:38:08 +02:00
drm	Merge tag 'topic/drm-misc-2016-03-14' of git://anongit.freedesktop.org/drm-intel into drm-next	2016-03-16 11:09:26 +10:00
linux	byteswap: try to avoid __builtin_constant_p gcc bug	2016-05-05 17:38:53 -07:00
misc	cxl: Support to flash a new image on the adapter from a guest	2016-03-09 23:39:56 +11:00
mtd	mtd: mtd-user: remove stdint.h include	2015-10-19 18:19:06 -07:00
rdma	Merge branches 'i40iw', 'sriov' and 'hfi1' into k.o/for-4.6	2016-03-21 17:32:23 -04:00
scsi	cxlflash: Fix to avoid virtual LUN failover failure	2016-01-06 20:50:08 -05:00
sound	ALSA: seq: Provide card number / PID via sequencer client info	2016-03-08 10:52:52 +01:00
video
xen	xen/gntdev: add ioctl for grant copy	2016-01-07 13:21:53 +00:00
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