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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2012-05-15 09:20:06 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2012-05-16 14:42:46 +0200
commiteda0c6d6b04d3cf72f5e8d656e39bffe3568e6db (patch)
tree5f57e3581729dfad7a7999ee24fd044b47018b8e /usr/Makefile
parente5b8d7553f87d939295e9eb0ca699c0030dc5ff1 (diff)
s390: fix race on TIF_MCCK_PENDING
There is a small race window in the __switch_to code in regard to the transfer of the TIF_MCCK_PENDING bit from the previous to the next task. The bit is transferred before the task struct pointer and the thread-info pointer for the next task has been stored to lowcore. If a machine check sets the TIF_MCCK_PENDING bit between the transfer code and the store of current/thread_info the bit is still set for the previous task. And if the previous task has terminated it can get lost. The effect is that a pending CRW is not retrieved until the next machine checks sets TIF_MCCK_PENDING. To fix this reorder __switch_to to first store the task struct and thread-info pointer and then do the transfer of the bit. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'usr/Makefile')
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