Messages in this thread | | | From | Deepa Dinamani <> | Date | Mon, 27 Mar 2017 14:02:46 -0700 | Subject | Re: [PATCH] trace: Make trace_hwlat timestamp y2038 safe |
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>>> > >>> > kernel/trace/trace_output.c: In function 'trace_hwlat_print': >>> >>> kernel/trace/trace_output.c:1168:5: warning: format '%lld' expects argument of type 'long long int', but argument 6 has type '__kernel_time_t' [-Wformat=] >>> > field->timestamp.tv_nsec); >>> >>> This happens on 64-bit architectures because 'struct timespec64' is defined to >>> be equal to 'struct timespec', which has a 'long' tv_sec rather than >>> 'long long'. >>> >>> A cast to 's64' is probably the best workaround.
We have been using long long cast to print timespec64 tv_sec.
I'm not sure what format specifier we would use if we cast to s64. printk-formats suggests %lld or %llx. Meaning a cast to long long.
>>> >>> > kernel/trace/trace_output.c: In function 'trace_hwlat_raw': >>> > kernel/trace/trace_output.c:1202:5: warning: format '%lld' expects argument of type 'long long int', but argument 5 has type '__kernel_time_t' [-Wformat=] >>> > field->seqnum); >>> >>> Same here. >>> >> >> Actually, I believe that "%zd" will work. It's made to work with size_t >> which is long long on 32 and long on 64. > > size_t is always 'long', not 'long long'. We have %pad for dma_addr_t > which may be 'long' or 'long long', but it is configuration dependent > which one it is on 32-bit. > > We could probably introduce a %pts format string for timespec64 > and have that pretty-printed.
dma_addr_t can be u64 or u32 based on architecture be it 32 bit or 64 bit. But, timespec64 tv_sec is always s64. This is the opposite problem from dma_addr_t that it is 64 bits regardless of architecture. So, wouldn't it be easier to use long long cast for tv_sec and then print tv_nsec as long?
-Deepa
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