forked from Minki/linux
5db9fa9593
There are two problems in the powerpc gettimeofday code which can cause incorrect results to be returned. The first is that there is a race between do_gettimeofday and the timer interrupt: 1. do_gettimeofday does get_tb() 2. decrementer exception on boot cpu which runs timer_recalc_offset, which also samples the timebase and updates the do_gtod structure with a greater timebase value. 3. do_gettimeofday calls __do_gettimeofday, which leads to the negative result from tb_val - temp_varp->tb_orig_stamp. The second is caused by taking the boot cpu offline, which can cause the value of tb_last_jiffy to be increased past the currently available timebase, causing the same underflow as above. [paulus@samba.org - define and use data_barrier() instead of mb().] Signed-off-by: Nathan Lynch <ntl@pobox.com> Signed-off-by: Paul Mackerras <paulus@samba.org> |
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