intrng: intr_isrc_dispatch() return stray count instead of condition

[ehem_freebsd_m5p.com]

Summary

Other platforms limit the number of times a given stray interrupt is
reported. Since the only error returned by intr_isrc_dispatch() is for
stray interrupts, returning the count instead makes sense.

[ehem_freebsd_m5p.com]

Instead switch to returning stray count. This allows limiting the stray count reports (x86 and PPC report a maximum of 5). Seems a more useful return value (all callers compare with 0).

[markj]

sys/kern/subr_intr.c

236

Do you mean to return the post-increment value?

[ehem_freebsd_m5p.com]

Yeah, bit of an issue here.

[ehem_freebsd_m5p.com]

That would be an issue, so now adjusted. As I imagine you've noticed, I've got vague hopes of making intr_isrc_dispatch() and
intr_execute_handlers() match.

[emaste]

sys/kern/subr_intr.c

363

maybe mention meaning of return value in comment?