[PATCH 1/3] dell-laptop: Clear buffer before each SMBIOS call

["Pali Rohár" <pali.rohar@gmail.com>]

Make sure that before initializing SMBIOS call input buffer does not contain
any garbage (e.g values from previous SMBIOS call). This fix problem with
passing undefined/random parameters to SMBIOS functions.

Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
---
 drivers/platform/x86/dell-laptop.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
index 35758cb..6728487 100644
--- a/drivers/platform/x86/dell-laptop.c
+++ b/drivers/platform/x86/dell-laptop.c
@@ -310,10 +310,15 @@ static DEFINE_MUTEX(buffer_mutex);
 
 static int hwswitch_state;
 
+static void clear_buffer(void)
+{
+	memset(buffer, 0, sizeof(struct calling_interface_buffer));
+}
+
 static void get_buffer(void)
 {
 	mutex_lock(&buffer_mutex);
-	memset(buffer, 0, sizeof(struct calling_interface_buffer));
+	clear_buffer();
 }
 
 static void release_buffer(void)
@@ -557,6 +562,8 @@ static int dell_rfkill_set(void *data, bool blocked)
 	    !(buffer->output[1] & BIT(16)))
 		disable = 1;
 
+	clear_buffer();
+
 	buffer->input[0] = (1 | (radio<<8) | (disable << 16));
 	dell_send_request(buffer, 17, 11);
 
@@ -571,6 +578,7 @@ static void dell_rfkill_update_sw_state(struct rfkill *rfkill, int radio,
 	if (status & BIT(0)) {
 		/* Has hw-switch, sync sw_state to BIOS */
 		int block = rfkill_blocked(rfkill);
+		clear_buffer();
 		buffer->input[0] = (1 | (radio << 8) | (block << 16));
 		dell_send_request(buffer, 17, 11);
 	} else {
@@ -774,6 +782,7 @@ static int __init dell_setup_rfkill(void)
 	dell_send_request(buffer, 17, 11);
 	status = buffer->output[1];
 	buffer->input[0] = 0x2;
+	clear_buffer();
 	dell_send_request(buffer, 17, 11);
 	hwswitch_state = buffer->output[1];
 	release_buffer();
-- 
1.7.9.5