From: Andreas Fenkart <afenkart@gmail.com>
Date: Fri, 17 Jul 2015 07:13:05 +0000 (+0200)
Subject: mwifiex: remove CMD_F_CANCELED flag
X-Git-Tag: firefly_0821_release~176^2~1159^2~124^2~58
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=e9f21d403699a4d299a02df107326f11acecd13e;p=firefly-linux-kernel-4.4.55.git

mwifiex: remove CMD_F_CANCELED flag

CMD_F_CANCELED was used to abort mwifiex_process_cmdresp in
case it already started or starts processing the cmd.
But this was probably not working the way intended:
- it is racy: mwifiex_process_cmdresp might already have passed that
  test and is continuing to use the cmd node being recycled
- mwifiex_process_cmdresp repeatedly uses adapter->curr_cmd which
  we just set to NULL
- mwifiex_recycle_cmd_node will clear the flag

The reason why it probably works is that mwifiex_cancel_pending_ioctl
is only called from mwifiex_cmd_timeout_func, where the there is little
chance of a command response still arriving

Signed-off-by: Andreas Fenkart <afenkart@gmail.com>
Acked-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
---

diff --git a/drivers/net/wireless/mwifiex/cmdevt.c b/drivers/net/wireless/mwifiex/cmdevt.c
index 87b6dee2b049..6458e17304ca 100644
--- a/drivers/net/wireless/mwifiex/cmdevt.c
+++ b/drivers/net/wireless/mwifiex/cmdevt.c
@@ -807,17 +807,6 @@ int mwifiex_process_cmdresp(struct mwifiex_adapter *adapter)
 	adapter->is_cmd_timedout = 0;
 
 	resp = (struct host_cmd_ds_command *) adapter->curr_cmd->resp_skb->data;
-	if (adapter->curr_cmd->cmd_flag & CMD_F_CANCELED) {
-		mwifiex_dbg(adapter, ERROR,
-			    "CMD_RESP: %#x been canceled\n",
-			    le16_to_cpu(resp->command));
-		mwifiex_recycle_cmd_node(adapter, adapter->curr_cmd);
-		spin_lock_irqsave(&adapter->mwifiex_cmd_lock, flags);
-		adapter->curr_cmd = NULL;
-		spin_unlock_irqrestore(&adapter->mwifiex_cmd_lock, flags);
-		return -1;
-	}
-
 	if (adapter->curr_cmd->cmd_flag & CMD_F_HOSTCMD) {
 		/* Copy original response back to response buffer */
 		struct mwifiex_ds_misc_cmd *hostcmd;
@@ -1090,10 +1079,18 @@ mwifiex_cancel_pending_ioctl(struct mwifiex_adapter *adapter)
 	    (adapter->curr_cmd->wait_q_enabled)) {
 		spin_lock_irqsave(&adapter->mwifiex_cmd_lock, cmd_flags);
 		cmd_node = adapter->curr_cmd;
-		cmd_node->cmd_flag |= CMD_F_CANCELED;
-		mwifiex_recycle_cmd_node(adapter, cmd_node);
+		/* setting curr_cmd to NULL is quite dangerous, because
+		 * mwifiex_process_cmdresp checks curr_cmd to be != NULL
+		 * at the beginning then relies on it and dereferences
+		 * it at will
+		 * this probably works since mwifiex_cmd_timeout_func
+		 * is the only caller of this function and responses
+		 * at that point
+		 */
 		adapter->curr_cmd = NULL;
 		spin_unlock_irqrestore(&adapter->mwifiex_cmd_lock, cmd_flags);
+
+		mwifiex_recycle_cmd_node(adapter, cmd_node);
 	}
 
 	/* Cancel all pending scan command */
diff --git a/drivers/net/wireless/mwifiex/fw.h b/drivers/net/wireless/mwifiex/fw.h
index cff38ad129aa..9a8c1832d068 100644
--- a/drivers/net/wireless/mwifiex/fw.h
+++ b/drivers/net/wireless/mwifiex/fw.h
@@ -438,7 +438,6 @@ enum P2P_MODES {
 
 
 #define CMD_F_HOSTCMD           (1 << 0)
-#define CMD_F_CANCELED          (1 << 1)
 
 #define HostCmd_CMD_ID_MASK             0x0fff