diag: Add sysfs parameter to control diag mask clear

This patch adds syfs parameter which controls clearing
of the peripheral masks upon USB disconnect and stopping
ODL.
This patch takes proper care for handling buffers
while clearing masks.

CRs-Fixed: 1081142
Change-Id: Ibe070661618258513d683bfec13ff10f23bee5d6
Signed-off-by: Manoj Prabhu B <bmanoj@codeaurora.org>

4 files changed, 36 insertions, 7 deletions

diff --git a/drivers/char/diag/diag_usb.c b/drivers/char/diag/diag_usb.c
index ca54b24ec604..0a0fc4400de5 100644
--- a/drivers/char/diag/diag_usb.c
+++ b/drivers/char/diag/diag_usb.c
@@ -14,6 +14,7 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/device.h>
+#include <linux/kernel.h>
 #include <linux/err.h>
 #include <linux/sched.h>
 #include <linux/ratelimit.h>
@@ -218,7 +219,8 @@ static void usb_disconnect(struct diag_usb_info *ch)
 	if (!ch)
 		return;
 
-	if (!atomic_read(&ch->connected) && driver->usb_connected)
+	if (!atomic_read(&ch->connected) &&
+		driver->usb_connected && diag_mask_param())
 		diag_clear_masks(NULL);
 
 	if (ch && ch->ops && ch->ops->close)
diff --git a/drivers/char/diag/diagchar.h b/drivers/char/diag/diagchar.h
index 67db49badf21..1488f9dc4300 100644
--- a/drivers/char/diag/diagchar.h
+++ b/drivers/char/diag/diagchar.h
@@ -632,6 +632,7 @@ void diag_cmd_remove_reg(struct diag_cmd_reg_entry_t *entry, uint8_t proc);
 void diag_cmd_remove_reg_by_pid(int pid);
 void diag_cmd_remove_reg_by_proc(int proc);
 int diag_cmd_chk_polling(struct diag_cmd_reg_entry_t *entry);
+int diag_mask_param(void);
 void diag_clear_masks(struct diag_md_session_t *info);
 
 void diag_record_stats(int type, int flag);
diff --git a/drivers/char/diag/diagchar_core.c b/drivers/char/diag/diagchar_core.c
index 76559633f387..9494314d18f0 100644
--- a/drivers/char/diag/diagchar_core.c
+++ b/drivers/char/diag/diagchar_core.c
@@ -144,6 +144,14 @@ module_param(max_clients, uint, 0);
 static struct timer_list drain_timer;
 static int timer_in_progress;
 
+/*
+ * Diag Mask clear variable
+ * Used for clearing masks upon
+ * USB disconnection and stopping ODL
+ */
+static int diag_mask_clear_param = 1;
+module_param(diag_mask_clear_param, int, 0644);
+
 struct diag_apps_data_t {
 	void *buf;
 	uint32_t len;
@@ -390,7 +398,10 @@ static uint32_t diag_translate_kernel_to_user_mask(uint32_t peripheral_mask)
 
 	return ret;
 }
-
+int diag_mask_param(void)
+{
+	return diag_mask_clear_param;
+}
 void diag_clear_masks(struct diag_md_session_t *info)
 {
 	int ret;
@@ -423,7 +434,8 @@ static void diag_close_logging_process(const int pid)
 	if (!session_info)
 		return;
 
-	diag_clear_masks(session_info);
+	if (diag_mask_clear_param)
+		diag_clear_masks(session_info);
 
 	mutex_lock(&driver->diag_maskclear_mutex);
 	driver->mask_clear = 1;
diff --git a/drivers/char/diag/diagfwd.c b/drivers/char/diag/diagfwd.c
index 876b455624b2..a7069bc0edf3 100644
--- a/drivers/char/diag/diagfwd.c
+++ b/drivers/char/diag/diagfwd.c
@@ -1232,6 +1232,8 @@ static int diagfwd_mux_open(int id, int mode)
 
 static int diagfwd_mux_close(int id, int mode)
 {
+	uint8_t i;
+
 	switch (mode) {
 	case DIAG_USB_MODE:
 		driver->usb_connected = 0;
@@ -1252,10 +1254,22 @@ static int diagfwd_mux_close(int id, int mode)
 		 */
 	} else {
 		/*
-		* With clearing of masks on ODL exit and
-		* USB disconnection, closing of the channel is
-		* not needed.This enables read and drop of stale packets.
-		*/
+		 * With sysfs parameter to clear masks set,
+		 * peripheral masks are cleared on ODL exit and
+		 * USB disconnection and buffers are not marked busy.
+		 * This enables read and drop of stale packets.
+		 *
+		 * With sysfs parameter to clear masks cleared,
+		 * masks are not cleared and buffers are to be marked
+		 * busy to ensure traffic generated by peripheral
+		 * are not read
+		 */
+		if (!(diag_mask_param())) {
+			for (i = 0; i < NUM_PERIPHERALS; i++) {
+				diagfwd_close(i, TYPE_DATA);
+				diagfwd_close(i, TYPE_CMD);
+			}
+		}
 		/* Re enable HDLC encoding */
 		pr_debug("diag: In %s, re-enabling HDLC encoding\n",
 		       __func__);