On Tue, 19 Jul 2022 14:06:11 -0700 Arun Easi <aeasi@xxxxxxxxxxx> wrote: > It appears by calling the above two interfaces, I get a separate instance > of "qla" only traces, but with only the "qla"-only instance being enabled, > leaving the main (/sys/kernel/tracing/events/qla/enable) one disabled. No > issues there, but when I enable both of them, I get garbage values on one. > > /sys/kernel/tracing/instances/qla2xxx/trace: > cat-56106 [012] ..... 2419873.470098: ql_dbg_log: qla2xxx [0000:05:00.0]-1054:14: Entered (null). > cat-56106 [012] ..... 2419873.470101: ql_dbg_log: qla2xxx [0000:05:00.0]-1000:14: Entered ×+<96>²Ü<98>^H. > cat-56106 [012] ..... 2419873.470102: ql_dbg_log: qla2xxx [0000:05:00.0]-1006:14: Prepare to issue mbox cmd=0xde589000. > > /sys/kernel/tracing/trace: > cat-56106 [012] ..... 2419873.470097: ql_dbg_log: qla2xxx [0000:05:00.0]-1054:14: Entered qla2x00_get_firmware_state. > cat-56106 [012] ..... 2419873.470100: ql_dbg_log: qla2xxx [0000:05:00.0]-1000:14: Entered qla2x00_mailbox_command. > cat-56106 [012] ..... 2419873.470102: ql_dbg_log: qla2xxx [0000:05:00.0]-1006:14: Prepare to issue mbox cmd=0x69. > > It appears that only one should be enabled at a time. Per my read of > Documentation/trace/ftrace.rst, the main directory and instances have > separate trace buffers, so I am a bit confused with the above output. That's because it uses va_list, and va_list can only be used once. I just added helpers for va_list use cases: https://lore.kernel.org/all/20220705224453.120955146@xxxxxxxxxxx/ But it will likely suffer the same issue, but I can easily fix that with this on top: Not even compiled tested: -- Steve diff --git a/include/trace/stages/stage6_event_callback.h b/include/trace/stages/stage6_event_callback.h index 0f51f6b3ab70..3c554a585320 100644 --- a/include/trace/stages/stage6_event_callback.h +++ b/include/trace/stages/stage6_event_callback.h @@ -40,7 +40,12 @@ #undef __assign_vstr #define __assign_vstr(dst, fmt, va) \ - vsnprintf(__get_str(dst), TRACE_EVENT_STR_MAX, fmt, *(va)) + do { \ + va_list __cp_va; \ + va_copy(__cp_va, *(va)); \ + vsnprintf(__get_str(dst), TRACE_EVENT_STR_MAX, fmt, __cp_va); \ + va_end(__cp_va); \ + } while (0) #undef __bitmask #define __bitmask(item, nr_bits) __dynamic_array(unsigned long, item, -1)
