On Mon, Dec 4, 2017 at 6:29 AM, Arnd Bergmann arnd@arndb.de wrote:
On Mon, Dec 4, 2017 at 1:55 AM, Deepa Dinamani deepa.kernel@gmail.com wrote:
struct timeval is not y2038 safe. All usage of timeval in the kernel will be replaced by y2038 safe structures. The change is also necessary as glibc is introducing support for 32 bit applications to use 64 bit time_t. Without this change, many applications would incorrectly interpret values in the struct input_event. More details about glibc at https://sourceware.org/glibc/wiki/Y2038ProofnessDesign .
struct input_event maintains time for each input event. Real time timestamps are not ideal for input as this time can go backwards as noted in the patch a80b83b7b8 by John Stultz. Hence, having the input_event.time fields only big enough for monotonic and boot times are sufficient.
The change leaves the representation of struct input_event as is on 64 bit architectures. But uses 2 unsigned long values on 32 bit machines to support real timestamps until year 2106. This intentionally breaks the ABI on 32 bit architectures and compat handling on 64 bit architectures. This is as per maintainer's preference to introduce compile time errors rather than run into runtime incompatibilities.
The change requires any 32 bit userspace utilities reading or writing from event nodes to update their reading format to match the new input_event. The changes to the popular libraries will be posted once we agree on the kernel change.
Suggested-by: Arnd Bergmann arnd@arndb.de Signed-off-by: Deepa Dinamani deepa.kernel@gmail.com
Reviewed-by: Arnd Bergmann arnd@arndb.de
This all looks good, I just have one small request:
struct input_event { +#if __BITS_PER_LONG != 32 || !defined(__USE_TIME_BITS64) 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
As we are getting closer to removing references to 'struct timeval' from the kernel, could you rephrase that conditional to
#if (__BITS_PER_LONG != 32 || !defined(__USE_TIME_BITS64)) && !defined(__KERNEL)
Thanks. Will do.
I just noticed that I left out the change to uinput for this patch. I will include that in the update as well.
-Deepa