On Wed, May 23, 2018 at 01:03:08PM +0200, Johannes Berg wrote:

On Wed, 2018-03-28 at 12:05 -0700, Alexei Starovoitov wrote:

quoted

fix iwlwifi_dev_ucode_error tracepoint to pass pointer to a table
instead of all 17 arguments by value.
dvm/main.c and mvm/utils.c have 'struct iwl_error_event_table'
defined with very similar yet subtly different fields and offsets.
tracepoint is still common and using definition of 'struct iwl_error_event_table'
from dvm/commands.h while copying fields.
Long term this tracepoint probably should be split into two.

It would've been nice to CC the wireless list for wireless related
patches ...

Ohh. I didn't realize that networking wireless doesn't fall under netdev.
I thought wireless folks are silent because they are embarrassed
by a function with 17 arguments.

quoted

--- a/drivers/net/wireless/intel/iwlwifi/iwl-devtrace.c
+++ b/drivers/net/wireless/intel/iwlwifi/iwl-devtrace.c

@@ -30,6 +30,7 @@
 #ifndef __CHECKER__
 #include "iwl-trans.h"
 
+#include "dvm/commands.h"

In particular, this breaks the whole driver abstraction.

quoted

+++ b/drivers/net/wireless/intel/iwlwifi/mvm/utils.c

@@ -549,12 +549,7 @@ static void iwl_mvm_dump_lmac_error_log(struct iwl_mvm *mvm, u32 base)
 
        IWL_ERR(mvm, "Loaded firmware version: %s\n", mvm->fw->fw_version);
 
-       trace_iwlwifi_dev_ucode_error(trans->dev, table.error_id, table.tsf_low,
-                                     table.data1, table.data2, table.data3,
-                                     table.blink2, table.ilink1,
-                                     table.ilink2, table.bcon_time, table.gp1,
-                                     table.gp2, table.fw_rev_type, table.major,
-                                     table.minor, table.hw_ver, table.brd_ver);
+       trace_iwlwifi_dev_ucode_error(trans->dev, &table, table.hw_ver, table.brd_ver);

This is also utterly wrong because mvm has - for better or worse - a
different type "struct iwl_error_event_table" in this file ...

As I was trying to explain in the commit log the single struct
is used in both places, but differences in two
"struct iwl_error_event_table" are carefully matched
field and by field. For two extra fields it was not
possible and they are passed separately as you can see above.
I still believe that tracepoint output is still exactly
the same before and after the patch.
I guess you see the breakage because new fields got
added into one "struct iwl_error_event_table",
but were not added to its evil twin "struct iwl_error_event_table"
with the same name after the patch landed ?
imo wireless folks need to avoid such naming conflicts.
I suggest to isolate common fields into separate base struct and
give two children structs different names.