On Tue, Nov 28, 2017 at 6:17 AM, Arnd Bergmann arnd@arndb.de wrote:
On Mon, Nov 27, 2017 at 11:29 PM, Deepa Dinamani deepa.kernel@gmail.com wrote:
I decided against using LEGACY_TIME_SYSCALLS to conditionally compile legacy time syscalls such as sys_nanosleep because this will need to enclose compat_sys_nanosleep as well. So, defining it as
config LEGACY_TIME_SYSCALLS def_bool 64BIT || !64BIT_TIME
will not include compat_sys_nanosleep. We will instead need a new config to exclusively mark legacy syscalls.
Do you mean we would need to do this separately for native and compat syscalls, and have yet another option, like LEGACY_TIME_SYSCALLS and LEGACY_TIME_COMPAT_SYSCALLS, to cover all cases? I would think that CONFIG_COMPAT_32BIT_TIME handles all the compat versions, while CONFIG_LEGACY_TIME_SYSCALLS handles all the native ones.
I meant sys_nanosleep would be covered by LEGACY_TIME_SYSCALLS, but compat_sys_nanosleep would be covered by CONFIG_COMPAT_32BIT_TIME along with other compat syscalls. So, if we define the LEGACY_TIME_SYSCALLS as
"This controls the compilation of the following system calls: time, stime, gettimeofday, settimeofday, adjtimex, nanosleep,alarm, getitimer, setitimer, select, utime, utimes, futimesat, and {old,new}{l,f,}stat{,64}. These all pass 32-bit time_t arguments on 32-bit architectures and are replaced by other interfaces (e.g. posix timers and clocks, statx). C libraries implementing 64-bit time_t in 32-bit architectures have to implement the handles by wrapping around the newer interfaces. New architectures should not explicitly enable this."
This would not be really true as compat interfaces have nothing to do with this config.
I was proposing that we could have LEGACY_TIME_SYSCALLS config, but then have all these "deprecated" syscalls be enclosed within this, compat or not. This will also mean that we will have to come up representing these syscalls in the syscall header files. This can be a separate patch and this series can be merged as is if everyone agrees.
I think doing this separately would be good, I don't see any interdependency with the other patches, we just need to decide what we want in the long run.
Right. There are three options:
1. Use two configs to identify which syscalls need not be supported by new architectures. In this case it makes sense to say LEGACY_TIME_SYSCALLS and COMPAT_32BIT_TIME both need to be disabled for new architectures. And, I can reword the config to what you mention below.
2. Make the LEGACY_TIME_SYSCALLS eliminate non y2038 safe syscalls mentioned below only. In this case only the native and compat functions of the below mentioned syscalls need to be identified by the config. I like this option as this clearly identifies which syscalls are deprecated and do not have a 64 bit counterpart. Not all architectures need to support turning this off.
3. If we don't need either 1 or 2, then we could stick with what we have today in the series as CONFIG_64BIT_TIME will be deleted and they only need #ifdef CONFIG_64BIT.
Let me know if anyone prefers something else.
I agree my text that you cited doesn't capture the situation correctly, as this is really about the obsolete system calls that take 64-bit time_t arguments on architectures that are converted to allow 64-bit time_t for non-obsolete system calls.
Maybe it's better to just reword this to
"This controls the compilation of the following system calls: time, stime, gettimeofday, settimeofday, adjtimex, nanosleep,alarm, getitimer, setitimer, select, utime, utimes, futimesat, and {old,new}{l,f,}stat{,64}. These are all replaced by other interfaces (e.g. posix timers and clocks, statx) on architectures that got converted from 32-bit time_t to 64-bit time_t. C libraries implementing 64-bit time_t in 32-bit architectures have to implement the handles by wrapping around the newer interfaces. New architectures should not explicitly enable this."
That would clarify that it's not about the compat system calls, while also allowing the two options to be set independently.
-Deepa