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In >> some cases this was not sufficient for a system. For >> example, a system with multiple (4+) PCIe cards each >> with 4 PTP-capable ethernet interfaces could run out >> of the available PPS major:minors if each interface >> registers a PPS source. >> >> Signed-off-by: Charlie Johnston >> --- >>   include/uapi/linux/pps.h | 2 +- >>   1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/include/uapi/linux/pps.h b/include/uapi/linux/pps.h >> index 009ebcd8ced5..85f472330da8 100644 >> --- a/include/uapi/linux/pps.h >> +++ b/include/uapi/linux/pps.h >> @@ -26,7 +26,7 @@ >>   #include >>     #define PPS_VERSION        "5.3.6" >> -#define PPS_MAX_SOURCES        16        /* should be enough... */ >> +#define PPS_MAX_SOURCES        (MINORMASK + 1) >>     /* Implementation note: the logical states ``assert'' and ``clear'' >>    * are implemented in terms of the chip register, i.e. ``assert'' > > I have just one question: are you sure that it's safe to call idr_alloc(..., 0, (MINORMASK + 1), ...)? > > Ciao, > > Rodolfo > Thanks for taking a look! My understanding is that idr_alloc(..., start, end, ...) can take any end value up to INT_MAX. It also handles any values <= 0 by treating them as equal to INT_MAX + 1 since the end value is non-inclusive. I can't think of any reason using MINORMASK + 1 here would be an issue since it's much less than the maximum value idr_alloc() allows. A number of drivers (e.g. ptp) just explicitly use a start and end value of 0, but I don't think that change would fit here. Regards, Charlie