From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759243AbbGHVhI (ORCPT ); Wed, 8 Jul 2015 17:37:08 -0400 Received: from mout.kundenserver.de ([212.227.126.187]:57286 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755625AbbGHVhA (ORCPT ); Wed, 8 Jul 2015 17:37:00 -0400 From: Arnd Bergmann To: Bamvor Zhang Jian Cc: john.stultz@linaro.org, tglx@linutronix.de, y2038@lists.linaro.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v2 4/4] y2038: convert ppdev to 2038 safe Date: Wed, 08 Jul 2015 23:36:57 +0200 Message-ID: <49534560.brEEJ92L0L@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.16.0-10-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: <1435587807-10008-5-git-send-email-bamvor.zhangjian@linaro.org> References: <1435587807-10008-1-git-send-email-bamvor.zhangjian@linaro.org> <1435587807-10008-5-git-send-email-bamvor.zhangjian@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:9kfP2KJEVF/c6tcZuO9+nT5c8/eUt78GPYpDA/PeYRE2/z7DzrF zDUz+wHwNoKuhn8OXHsw+974BIFl+k5VvxI/nP5iVyw5F5sfTSzXK8QAej8t+bgjsY+58zI YH/OSWqaP/68vTbJjDQqD0vNzNay2wH3MVIk02ct7fBjT/QrVBUkfKbI5EciEFNwO0AehR9 oFL08idrmx5VZM68AaltQ== X-UI-Out-Filterresults: notjunk:1;V01:K0:6/1xhM/oIQo=:P6F8nJZn9ulPYWGNWzMhEp lkfmSW3eSkrGSVN7jU4S//abjjj2aa+DjDtkRB8XGqEGSu2VL77J6ISVvPf8ut71MO7lTA8yv 8ei2d6ri8vCqlipqJQlKD4Q2RK1RDMM5pK2YJrHIQTqLjTSDBABQAwRSJdzX3tl71TulENdlY SMLP0OeWzHw0q9g96X0gN31i0UwYZkTnVboHFnYFT+yQteJGs+fIk6zDU/jBQ96R6WRRO2JXV 2IyyftkgrFCFKZ5FY1KybIWUn5QFu3pC4NkQ8JF2UIm3GdCtaCoBazo/ChNeMiCr9uFDH5ueA aMdcCWBP4+U81kusfkotAOBF0LAqyD9mAeNW/HsCeFccrbDyun7qpaYxIbL9AYTTQv76w61mL NHr10j8ZP52BKBlU3qr8BedV9szbvtVWlY1qpdIjnwTZ0uF9D/kJKKdsWmF2+Jiw80EYdCrHq YuWW3DvGzUwegA7kg2CeJ2Lt+jdqJAVnzyQIF5cSea0pxAhvMkYeCkS2wD11R9xhzNJLlDs7Z rPsZ0VIcYRkpYqaPQd4EpMQgv94z5vY73mryAX8K22Yi82Qv/tNov27ZDAWdO2OTey8pcPwNj WEqQs5FlJOUjYnFzsoBbLEPxVCkw+99YLHS9trynIRW/xVux6SV9ljTSMUjx1D43jvmDsTmoq X0gTgZvN/X1MCq0x4eXxnMiiBMbeHuEi/yNyUVBsnoxdyDQ== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Monday 29 June 2015 22:23:27 Bamvor Zhang Jian wrote: > diff --git a/include/uapi/linux/ppdev.h b/include/uapi/linux/ppdev.h > index dc18c5d..d62a47d 100644 > --- a/include/uapi/linux/ppdev.h > +++ b/include/uapi/linux/ppdev.h > @@ -74,8 +74,18 @@ struct ppdev_frob_struct { > #define PPSETPHASE _IOW(PP_IOCTL, 0x94, int) > > /* Set and get port timeout (struct timeval's) */ > -#define PPGETTIME _IOR(PP_IOCTL, 0x95, struct timeval) > -#define PPSETTIME _IOW(PP_IOCTL, 0x96, struct timeval) > +/* Force application use 64 time_t ioctl */ > +/* TODO: It is an open question about we should use a __xxx_timeval or an > + * implicit array. > + * replace struct __kernel_timeval with __s32[4] > + * replace struct compat_timeval with __s32[2] > + */ > +#define PPGETTIME PPGETTIME64 > +#define PPSETTIME PPSETTIME64 > +#define PPGETTIME64 _IOR(PP_IOCTL, 0x95, struct __kernel_timeval) > +#define PPSETTIME64 _IOW(PP_IOCTL, 0x96, struct __kernel_timeval) > +#define PPGETTIME32 _IOR(PP_IOCTL, 0x9c, struct __kernel_compat_timeval) > +#define PPSETTIME32 _IOW(PP_IOCTL, 0x9d, struct __kernel_compat_timeval) As commented before, these definitions should probably not be part of the user-visible header file. The main reason for using an __s64[2] array instead of struct __kernel_timeval is to avoid adding __kernel_timeval: 'timeval' is thoroughly deprecated and we don't want to establish new interfaces with that. In case of this driver, nobody would ever want to change their user space to use a 64-bit __kernel_timeval instead of timeval and explicitly call PPGETTIME64 instead of PPGETTIME, because we are only dealing with an interval here, and a 32-bit second value is sufficient to represent that. Instead, the purpose of your patch is to make the kernel cope with user space that happens to use a 64-bit time_t based definition of 'struct timeval' and passes that to the ioctl. Arnd [re-sent with fixed y2038 list]