Subject: Re: [PATCH v2 0/2] vfs: Define new syscall getumask.
To: Josh Triplett <josh@joshtriplett.org>,
        Greg KH <gregkh@linuxfoundation.org>
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Cc: "Theodore Ts'o" <tytso@mit.edu>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        "Richard W.M. Jones" <rjones@redhat.com>, linux-kernel@vger.kernel.org,
        Thomas Gleixner <tglx@linutronix.de>, mingo@redhat.com,
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        adobriyan@gmail.com, Davidlohr Bueso <dave@stgolabs.net>,
        linux-api <linux-api@vger.kernel.org>, gorcunov@gmail.com,
        fw@deneb.enyo.de, Linus Torvalds <torvalds@linux-foundation.org>
From: "H. Peter Anvin" <hpa@zytor.com>
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Date: Sun, 17 Apr 2016 19:15:31 -0700
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On 04/17/16 19:12, Josh Triplett wrote:
>>
>> I really like the 'libinux' idea, did anyone every hack up a first-pass
>> at this?  And I'm guessing we have more syscalls now that would need to
>> be added (like getrandom(), but that shouldn't be too difficult.
> 
> Personally, I'd suggest that libinux should wire up *all* (non-obsolete)
> syscalls, not just those that haven't already been exposed via any
> particular libc implementation.  Each such syscall function would have
> minimal overhead, since unlike libc these wrappers would not have any
> special handling (other than use of the vdso) and would directly map to
> the kernel syscall signature.  Given a standard prefix like sys_ or
> linux_, that would provide a clear distinction between direct-syscall
> functions and libc functions, and avoid any future conflict if libc adds
> a function named the same as the syscall.
> 
> As a random example, sys_getpid() would *always* call the getpid
> syscall, rather than reading a cache within the library.  (And
> sys_gettid would call the gettid syscall, rather than failing to exist.)
> 

I'm not so sure this is a good idea.  It has definite pros and cons.  In
some ways it pushes it more to be like syscall(3).

	-hpa