Y2038 July 2016

y2038@lists.linaro.org

5 participants
6 discussions

[PATCH 0/7] [media] y2038 conversion for subsystem

by Arnd Bergmann

Hi everyone, This is a conversion of all subsystem-wide v4l2 code to avoid the use of types based on time_t. The first five patches should all be harmless and obvious, so they can get applied for 4.3 after normal review. The last two patches are marked RFC for now because their possible impact on the user space ABI and to decide if this is the best approach or whether we should instead introduce extra code in the kernel to handle modified user space. There are a few device drivers beyond this series that rely on time_t/timeval/timespec internally, but they are all easy to fix and can be taken care of later. Arnd Arnd Bergmann (7): [media] dvb: use ktime_t for internal timeout [media] dvb: remove unused systime() function [media] dvb: don't use 'time_t' in event ioctl [media] exynos4-is: use monotonic timestamps as advertized [media] use v4l2_get_timestamp where possible [RFC] [media]: v4l2: introduce v4l2_timeval [RFC] [media] introduce v4l2_timespec type for timestamps drivers/media/dvb-core/demux.h | 2 +- drivers/media/dvb-core/dmxdev.c | 2 +- drivers/media/dvb-core/dvb_demux.c | 17 ++++++----------- drivers/media/dvb-core/dvb_demux.h | 4 ++-- drivers/media/dvb-core/dvb_net.c | 2 +- drivers/media/dvb-frontends/dibx000_common.c | 10 ---------- drivers/media/dvb-frontends/dibx000_common.h | 2 -- drivers/media/pci/bt8xx/bttv-driver.c | 7 ++----- drivers/media/pci/cx18/cx18-mailbox.c | 2 +- drivers/media/pci/meye/meye.h | 2 +- drivers/media/pci/zoran/zoran.h | 2 +- drivers/media/platform/coda/coda.h | 2 +- drivers/media/platform/exynos4-is/fimc-capture.c | 8 +------- drivers/media/platform/exynos4-is/fimc-lite.c | 7 +------ drivers/media/platform/omap/omap_vout.c | 4 ++-- drivers/media/platform/omap3isp/ispstat.c | 5 ++--- drivers/media/platform/omap3isp/ispstat.h | 2 +- drivers/media/platform/s3c-camif/camif-capture.c | 8 +------- drivers/media/platform/vim2m.c | 2 +- drivers/media/platform/vivid/vivid-ctrls.c | 2 +- drivers/media/usb/cpia2/cpia2.h | 2 +- drivers/media/usb/cpia2/cpia2_v4l.c | 2 +- drivers/media/usb/gspca/gspca.c | 6 +++--- drivers/media/usb/usbvision/usbvision.h | 2 +- drivers/media/v4l2-core/v4l2-common.c | 6 +++--- drivers/media/v4l2-core/v4l2-event.c | 20 +++++++++++++------- drivers/staging/media/omap4iss/iss_video.c | 5 +---- include/media/v4l2-common.h | 2 +- include/media/videobuf-core.h | 2 +- include/trace/events/v4l2.h | 12 ++++++++++-- include/uapi/linux/dvb/video.h | 3 ++- include/uapi/linux/omap3isp.h | 2 +- include/uapi/linux/videodev2.h | 16 ++++++++++++++-- 33 files changed, 79 insertions(+), 93 deletions(-) -- 2.1.0.rc2

6 years, 3 months

Re: [Y2038] Fourth draft of the Y2038 design document

by Arnd Bergmann

On Wednesday, June 22, 2016 12:58:38 AM CEST Albert ARIBAUD wrote: > Hi all, > > I have produced a fourth draft of what will eventually become the Y2038 > design document: > > https://sourceware.org/glibc/wiki/Y2038ProofnessDesign?rev=83 > > Relative to the previous draft: > > * the scope clarifies that *only* Y2038 is considered, and no other > doomsday such as Y2106 or Y9999; > > * all types directly or indirectly derived from time_t are now listed; > > * all APIs using these types are now listed; > > * all functions which use time_t internally are now listed; > > * also listed are types and APIs related to time but which are > Y2038-safe (even though they might be unsafe for some other > doomsday, e.g. struct rpc_timeval being Y2106-unsafe). > > As always, comments welcome. I've cross-checked your list of data structures with the one I have for the kernel at https://docs.google.com/spreadsheets/d/1HCYwHXxs48TsTb6IGUduNjQnmfRvMPzCN6T… I noticed 'struct sysinfo' as another interface that holds a time, even though this is documented as 'long' and I concluded that we won't need to change it, that should probably be documented. 'struct rusage' is also interesting, as there is no overflow in 2038, but instead it could overflow on large machines (hundreds of CPUs) with very long-running tasks (months), so I'm unsure how to treat that from the kernel side. It's also one of very few kernel interfaces using 'timeval' rather than 'timespec' (we generally replaced the other ones). My current kernel patch series changes rusage by using 64-bit fields for everything, with the intention of having the same binary layout for 32-bit and 64-bit processes, and reusing the 64-bit syscall entry point for compat mode (running 32-bit tasks on a 64-bit kernel). Does that work for you? I think we should expand the ioctl section a bit: I can do most of it in the kernel, but need help from glibc for a few things in which we need to agree on calling conventions. Here is what I'd suggest having in the document, feel free to take that into your document or edit as you wish: == IOCTLs and Y2038 == Some Linux IOCTLs may be Y2038-unsafe, or use types defined by glibc that do not match the kernel internal types. Known important cases are: - An ioctl command number is defined using the _IOR/_IOW/_IORW macros by the kernel with a structure whose size changes based on glibc's time_t. The kernel can handle these transparently by implementing handlers for both command numbers with the correct structure format. - The binary ABI changes based on the glibc time_t type, but the command number does not change. In this case, the kernel header files defining the data structure will check the "__USE_TIME_BITS64" macro [do we need a new macro for the kernel headers?] to provide a different command number for the new data structure layout. glibc will define this macro at an appropriate location [where?] to make it visible before including kernel header files. - An ioctl command passes time information in a structure that is not based on time_t but another integer type that does not get changed. The kernel header files will provide both a new structure layout and command number when "__USE_TIME_BITS64" is set. [I can find examples for ioctl commands in each of those categories if needed.] == Socket options == Like ioctl(), setsockopt()/getsockopt() has a few interfaces that are passing time data: SO_TIMESTAMP/SO_TIMESTAMPNS/SO_TIMESTAMPING: These enable the timestamping infrastructure for a socket, which will consecutively return data to user space using "cmsg" data on the socket. The kernel does not know the layout of 'struct timespec' and 'struct timeval' when filling the cmsg data, so we need to define new binary values for the three flags, which then get used if __USE_TIME_BITS64 is set. SO_RCVTIMEO/SO_SNTTIMEO: These pass a 'struct timeval' and a length. Assuming that the 'optlen' argument of the setsockopt syscall always matches the size of 'struct timeval', the kernel will be able to access the data in the same format that was passed by glibc. [alternatively, we could handle this the same way as SO_TIMESTAMP*, using new numbers for the flags]. [end quote] Regarding the "Support for non-Y2038-safe kernels" section, I'm not sure if that can work at all: A kernel that does not have the appropriate system calls will also not have the handlers for a lot of the ioctl commands and possibly other interfaces that rely on a specific structure layout. If we can instead enforce that __USE_TIME_BITS64 is only set with a minimal version of kernel headers and that it implies binary compatibility with no older kernel version, we could avoid those problems. On your note "The implementation needs further thinking about, as application code defining _TIME_BITS=64 and gets built against new kernel headers and old GLIBC headers, then GLIBC will use 32-bit time_t and kernel will expect 64-bit time_t, and there is no way to ensure detection of this case.", I think that is covered by having the kernel headers check __USE_TIME_BITS64 instead of _TIME_BITS=64, as I described above. Arnd

7 years, 2 months

We could not deliver your parcel, #00000686170

by FedEx Standard Overnight

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7 years, 4 months

Shipment delivery problem #00000882372

by FedEx International Ground

Dear Customer, We could not deliver your parcel. Delivery Label is attached to this email. Yours trully, Russell Lucas, Support Manager.

7 years, 4 months

[PATCH] md: use seconds granularity for error logging

by Arnd Bergmann

The md code stores the exact time of the last error in the last_read_error variable using a timespec structure. It only ever uses the seconds portion of that though, so we can use a scalar for it. There won't be an overflow in 2038 here, because it already used monotonic time and 32-bit is enough for that, but I've decided to use time64_t for consistency in the conversion. Signed-off-by: Arnd Bergmann <arnd(a)arndb.de> --- drivers/md/md.c | 3 +-- drivers/md/md.h | 2 +- drivers/md/raid10.c | 11 +++++------ 3 files changed, 7 insertions(+), 9 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 3745b9a7a2d7..ad512ad4610f 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -3179,8 +3179,7 @@ int md_rdev_init(struct md_rdev *rdev) rdev->data_offset = 0; rdev->new_data_offset = 0; rdev->sb_events = 0; - rdev->last_read_error.tv_sec = 0; - rdev->last_read_error.tv_nsec = 0; + rdev->last_read_error = 0; rdev->sb_loaded = 0; rdev->bb_page = NULL; atomic_set(&rdev->nr_pending, 0); diff --git a/drivers/md/md.h b/drivers/md/md.h index 3c3412d85e42..20c667579ede 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -99,7 +99,7 @@ struct md_rdev { atomic_t read_errors; /* number of consecutive read errors that * we have tried to ignore. */ - struct timespec last_read_error; /* monotonic time since our + time64_t last_read_error; /* monotonic time since our * last read error */ atomic_t corrected_errors; /* number of corrected read errors, diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 41191e04d565..f8cdd08d0a40 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -2170,21 +2170,20 @@ static void recovery_request_write(struct mddev *mddev, struct r10bio *r10_bio) */ static void check_decay_read_errors(struct mddev *mddev, struct md_rdev *rdev) { - struct timespec cur_time_mon; + long cur_time_mon; unsigned long hours_since_last; unsigned int read_errors = atomic_read(&rdev->read_errors); - ktime_get_ts(&cur_time_mon); + cur_time_mon = ktime_get_seconds(); - if (rdev->last_read_error.tv_sec == 0 && - rdev->last_read_error.tv_nsec == 0) { + if (rdev->last_read_error == 0) { /* first time we've seen a read error */ rdev->last_read_error = cur_time_mon; return; } - hours_since_last = (cur_time_mon.tv_sec - - rdev->last_read_error.tv_sec) / 3600; + hours_since_last = (long)(cur_time_mon - + rdev->last_read_error) / 3600; rdev->last_read_error = cur_time_mon; -- 2.9.0

7 years, 4 months

[GIT PULL] Delete CURRENT_TIME_SEC and replace current_fs_time()

by Deepa Dinamani

7 years, 5 months

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Y2038 July 2016