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To: Bruce Evans <brde@optusnet.com.au>
Subject: Re: svn commit: r274017 - head/sys/kern
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From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
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--------
In message <20141104045159.E1605@besplex.bde.org>, Bruce Evans writes:

>This optimization is probably minor, but reminds me of other syscalls
>that would benefit using a single largish allocation up front:
>- all vfs calls that start with namei().  They allocate PATH_MAX (1K)
>   bytes and more.  An 8K stack has plently to spare after allocating
>   1K.  However, if malloc() is used then the PATH_MAX limit shouldn't
>   exist.   Only a limit to prevent denial of service is needed.

We should actually roll a new rev of all syscalls which take a path
and have them pass strlen(path)+1 into the kernel.

That would allow both precise allocation and faster copyin, followed
by a check that the last byte is (still) a NUL.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.