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From: Miri Korenblit <miriam.rachel.korenblit@intel.com>
To: johannes@sipsolutions.net
Cc: linux-wireless@vger.kernel.org,
	Johannes Berg <johannes.berg@intel.com>
Subject: [PATCH 09/15] wifi: iwlwifi: fw: add clarifying comments about iwl_fwrt_dump_data
Date: Tue, 19 Mar 2024 10:10:21 +0200
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From: Johannes Berg <johannes.berg@intel.com>

iwl_fw_dbg_collect_sync() unconditionally accesses 'trig' at
the beginning of the function, even though the data has an
inner union and 'trig' isn't necessarily always used, it can
be 'desc' instead. Add comments clarifying why this is OK,
that 'trig'/'desc' must be first in the struct and how in it
the use of the union's sub-structs is differentiated.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
---
 drivers/net/wireless/intel/iwlwifi/fw/dbg.c     | 1 +
 drivers/net/wireless/intel/iwlwifi/fw/runtime.h | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/drivers/net/wireless/intel/iwlwifi/fw/dbg.c b/drivers/net/wireless/intel/iwlwifi/fw/dbg.c
index c3bdf433d8f7..fe4e1bea30bb 100644
--- a/drivers/net/wireless/intel/iwlwifi/fw/dbg.c
+++ b/drivers/net/wireless/intel/iwlwifi/fw/dbg.c
@@ -3084,6 +3084,7 @@ static void iwl_fw_dbg_collect_sync(struct iwl_fw_runtime *fwrt, u8 wk_idx)
 	if (!test_bit(wk_idx, &fwrt->dump.active_wks))
 		return;
 
+	/* also checks 'desc' for pre-ini mode, since that shadows in union */
 	if (!dump_data->trig) {
 		IWL_ERR(fwrt, "dump trigger data is not set\n");
 		goto out;
diff --git a/drivers/net/wireless/intel/iwlwifi/fw/runtime.h b/drivers/net/wireless/intel/iwlwifi/fw/runtime.h
index b2bc4fd37abf..4204e999bbf2 100644
--- a/drivers/net/wireless/intel/iwlwifi/fw/runtime.h
+++ b/drivers/net/wireless/intel/iwlwifi/fw/runtime.h
@@ -46,6 +46,10 @@ struct iwl_fwrt_shared_mem_cfg {
  * struct iwl_fwrt_dump_data - dump data
  * @trig: trigger the worker was scheduled upon
  * @fw_pkt: packet received from FW
+ *
+ * Note that the decision which part of the union is used
+ * is based on iwl_trans_dbg_ini_valid(): the 'trig' part
+ * is used if it is %true, the 'desc' part otherwise.
  */
 struct iwl_fwrt_dump_data {
 	union {
@@ -54,6 +58,7 @@ struct iwl_fwrt_dump_data {
 			struct iwl_rx_packet *fw_pkt;
 		};
 		struct {
+			/* must be first to be same as 'trig' */
 			const struct iwl_fw_dump_desc *desc;
 			bool monitor_only;
 		};
-- 
2.34.1