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authorDeepa Dinamani2018-01-08 02:44:42 +0100
committerDmitry Torokhov2018-01-10 01:40:30 +0100
commit152194fe9c3f03232b9c0d0264793a7fa4af82f8 (patch)
tree2c21b0ba04050b8a86562e55aec816f9ea029c4b /include/uapi/linux/input.h
parentInput: silead - add support for capactive home button found on some x86 tablets (diff)
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Input: extend usable life of event timestamps to 2106 on 32 bit systems
The input events use struct timeval to store event time, unfortunately this structure is not y2038 safe and is being replaced in kernel with y2038 safe structures. Because of ABI concerns we can not change the size or the layout of structure input_event, so we opt to re-interpreting the 'seconds' part of timestamp as an unsigned value, effectively doubling the range of values, to year 2106. Newer glibc that has support for 32 bit applications to use 64 bit time_t supplies __USE_TIME_BITS64 define [1], that we can use to present the userspace with updated input_event layout. The updated layout will cause the compile time breakage, alerting applications and distributions maintainers to the issue. Existing 32 binaries will continue working without any changes until 2038. Ultimately userspace applications should switch to using monotonic or boot time clocks, as realtime clock is not very well suited for input event timestamps as it can go backwards (see a80b83b7b8 "Input: evdev - add CLOCK_BOOTTIME support" by by John Stultz). With monotonic clock the practical range of reported times will always fit into the pair of 32 bit values, as we do not expect any system to stay up for a hundred years without a single reboot. [1] https://sourceware.org/glibc/wiki/Y2038ProofnessDesign Suggested-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com> Acked-by: Peter Hutterer <peter.hutterer@who-t.net> Patchwork-Id: 10148083 Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Diffstat (limited to 'include/uapi/linux/input.h')
-rw-r--r--include/uapi/linux/input.h11
1 files changed, 11 insertions, 0 deletions
diff --git a/include/uapi/linux/input.h b/include/uapi/linux/input.h
index 8c5a0bf6ee35..7288a7c573cc 100644
--- a/include/uapi/linux/input.h
+++ b/include/uapi/linux/input.h
@@ -21,10 +21,21 @@
/*
* The event structure itself
+ * Note that __USE_TIME_BITS64 is defined by libc based on
+ * application's request to use 64 bit time_t.
*/
struct input_event {
+#if (__BITS_PER_LONG != 32 || !defined(__USE_TIME_BITS64)) && !defined(__KERNEL)
struct timeval time;
+#define input_event_sec time.tv_sec
+#define input_event_usec time.tv_usec
+#else
+ __kernel_ulong_t __sec;
+ __kernel_ulong_t __usec;
+#define input_event_sec __sec
+#define input_event_usec __usec
+#endif
__u16 type;
__u16 code;
__s32 value;