On Fri, 15 Mar 2013, notgeorge burns wrote:
> Does the hardirq handler need to do something to make the TI_flags
> work properly against _TIF_WORK_MASK ? _TIF_WORK_MASK doesn't
> include TIF_NEED_RESCHED so it seems that this wouldn't be the right
> way to do it?
To be honest I was puzzled for a second by that mysel after reading
your mail, but you got tricked by really obfuscated macro magic:
andl $_TIF_WORK_MASK, %ecx # is there any work to be done on
# int/exception return?
jne work_pending
So we jump to work_pending, if any bit of _TIF_WORK_MASK is set in ecx
#define _TIF_WORK_MASK \
(0x0000FFFF & \
~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT| \
_TIF_SINGLESTEP|_TIF_SECCOMP|_TIF_SYSCALL_EMU))
So we keep everything in 0xffff _except_ _TIF_SYSCALL_TRACE,
_TIF_SYSCALL_AUDIT, _TIF_SINGLESTEP, _TIF_SECCOMP, _TIF_SYSCALL_EMU
Note the "~" before (_TIF ...... EMU) !
So _TIF_NEED_RESCHED is preserved and checked and handled in
work_pending.
You made me worried for a second, but that code has been that way for
almost a decade, so RT would have stumbled over it at some point :)
Thanks,
tglx
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