Patch "iwlwifi: mvm: rs: don't override the rate history in the search cycle" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

iwlwifi: mvm: rs: don't override the rate history in the search cycle

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
iwlwifi-mvm-rs-don-t-override-the-rate-history-in-the-search-cycle.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Emmanuel Grumbach <[email protected]>
Date: Thu, 19 Oct 2017 21:36:04 +0300
Subject: iwlwifi: mvm: rs: don't override the rate history in the search cycle

From: Emmanuel Grumbach <[email protected]>

[ Upstream commit 992172e3aec19e5b0ea5b757ba40a146b9282d1e ]

When we are in a search cycle, we try different combinations of parameters. Those combinations are called 'columns'. When we switch to a new column, we first need to check if this column has a suitable rate, if not, we can't try it. This means we must not erase the statistics we gathered for the previous column until we are sure that we are indeed switching column.

The code that tries to switch to a new column first sets a whole bunch of things for the new column, and only then checks that we can find suitable rates in that column. While doing that, the code mistakenly erased the rate statistics. This code was right until
struct iwl_scale_tbl_info grew up for TPC.

Fix this to make sure we don't erase the rate statistics until we are sure that we can indeed switch to the new column.

Note that this bug is really harmless since it causes a change in the behavior only when we can't find any rate in the new column which should really not happen. In the case we do find a suitable we reset the rate statistics a few lines later anyway.

---
 drivers/net/wireless/intel/iwlwifi/mvm/rs.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

@@ -1867,12 +1867,10 @@ static int rs_switch_to_column(struct iw
 	struct rs_rate *rate = &search_tbl->rate;
 	const struct rs_tx_column *column = &rs_tx_columns[col_id];
 	const struct rs_tx_column *curr_column = &rs_tx_columns[tbl->column];
-	u32 sz = (sizeof(struct iwl_scale_tbl_info) -
-		  (sizeof(struct iwl_rate_scale_data) * IWL_RATE_COUNT));
 	unsigned long rate_mask = 0;
 	u32 rate_idx = 0;
 
-	memcpy(search_tbl, tbl, sz);
+	memcpy(search_tbl, tbl, offsetof(struct iwl_scale_tbl_info, win));
 
 	rate->sgi = column->sgi;
 	rate->ant = column->ant;

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/iwlwifi-mvm-rs-don-t-override-the-rate-history-in-the-search-cycle.patch