On 09/02/2011 12:18 PM, Arnaldo Carvalho de Melo wrote:
> Em Fri, Sep 02, 2011 at 10:03:46AM -0600, David Ahern escreveu:
>> if (type & PERF_SAMPLE_RAW) {
>> - u32 *p = (u32 *)array;
>> + u.val64 = *array;
>> + if (swapped) {
>> + static bool show_warn = true;
>> +
>> + /* undo swap of u64, then swap on individual u32s */
>> + u.val64 = bswap_64(u.val64);
>> + u.val32[0] = bswap_32(u.val32[0]);
>> + u.val32[1] = bswap_32(u.val32[1]);
>> +
>> + if (show_warn) {
>> + pr_warning("Endianness of raw data not
>> corrected!\n");
>> + show_warn = false;
>> + }
>> + }
>
> Can you use WARN_ONCE? Would become:
>
> if (WARN_ONCE(swapped, "Endianness of raw data not
> corrected!\n")) {
> /* undo swap of u64, then swap on individual u32s */
> u.val64 = bswap_64(u.val64);
> u.val32[0] = bswap_32(u.val32[0]);
> u.val32[1] = bswap_32(u.val32[1]);
> }
That's not quite what we need. The bswap's happen all the time; the warn
once is to tell the user one time that samples in the file contain raw
data and those cannot be programmatically adjusted for endianness.
ie., more like:
WARN_ONCE(swapped, "Endianness of raw data not corrected!\n");
and no action taken (the 'if (WARN_ONCE())'part).
David
>
> We have that and its the usual idiom in the kernel proper :-)
>
> See tools/perf/util/include/asm/bug.h and net/can/af_can.c can_rcv for
> an example.
>
> Thanks,
>
> - Arnaldo
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