From 722a0019796eb3246a5640e5d9ea1c32694103f8 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Pali=20Roh=C3=A1r?= Date: Mon, 4 Jan 2016 22:26:36 +0100 Subject: [PATCH] dell-wmi: Process only one event on devices with interface version 0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit BIOS/ACPI on devices with WMI interface version 0 does not clear buffer before filling it. So next time when BIOS/ACPI send WMI event which is smaller as previous then it contains garbage in buffer from previous event. BIOS/ACPI on devices with WMI interface version 1 clears buffer and sometimes send more events in buffer at one call. Since commit 5f5cd34284ca ("dell-wmi: Update code for processing WMI events") dell-wmi process all events in buffer (and not just first). To prevent reading garbage from the buffer we process only the first event on devices with WMI interface version 0. Signed-off-by: Pali Rohár Tested-by: Gabriele Mazzotta Signed-off-by: Darren Hart --- drivers/platform/x86/dell-wmi.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/drivers/platform/x86/dell-wmi.c b/drivers/platform/x86/dell-wmi.c index 1ad7a7b415745..5db9efbde5b93 100644 --- a/drivers/platform/x86/dell-wmi.c +++ b/drivers/platform/x86/dell-wmi.c @@ -237,6 +237,22 @@ static void dell_wmi_notify(u32 value, void *context) buffer_end = buffer_entry + buffer_size; + /* + * BIOS/ACPI on devices with WMI interface version 0 does not clear + * buffer before filling it. So next time when BIOS/ACPI send WMI event + * which is smaller as previous then it contains garbage in buffer from + * previous event. + * + * BIOS/ACPI on devices with WMI interface version 1 clears buffer and + * sometimes send more events in buffer at one call. + * + * So to prevent reading garbage from buffer we will process only first + * one event on devices with WMI interface version 0. + */ + if (dell_wmi_interface_version == 0 && buffer_entry < buffer_end) + if (buffer_end > buffer_entry + buffer_entry[0] + 1) + buffer_end = buffer_entry + buffer_entry[0] + 1; + while (buffer_entry < buffer_end) { len = buffer_entry[0]; -- 2.39.5