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PR/48028 CVS commit: src/sys/dev
The following reply was made to PR kern/48028; it has been noted by GNATS.
From: "Taylor R Campbell" <riastradh%netbsd.org@localhost>
Subject: PR/48028 CVS commit: src/sys/dev
Date: Sun, 21 Jul 2013 22:30:19 +0000
Module Name: src
Committed By: riastradh
Date: Sun Jul 21 22:30:19 UTC 2013
When reading from /dev/random, block at most once in cprng_strong.
We are not obligated to return exactly as many bytes as requested,
and many applications -- notably those that use stdio or otherwise
buffered I/O to read from /dev/random -- try to read many more than
32 bytes at a time from /dev/random even if all they are about to use
is 32 bytes.
In this case, blocking until we have enough entropy to fill a large
buffer causes needless application delays, e.g. causing cgdconfig
(which reads from /dev/random with stdio) to hang at boot when trying
to configure a random-keyed device for swap.
Patch tested by Aran Clauson. Fixes PR kern/48028.
To generate a diff of this commit:
cvs rdiff -u -r1.15 -r1.16 src/sys/dev/rndpseudo.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
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