CVS commit: src/sys/dev

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Sun Jul 21 22:30:19 UTC 2013

Modified Files:
        src/sys/dev: rndpseudo.c

Log Message:
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.