Date: Sun, 27 Oct 1996 09:55:48 +0200 From: Mark Murray <mark@grondar.za> To: Bruce Evans <bde@zeta.org.au> Cc: sos@freefall.freebsd.org, cvs-all@freefall.freebsd.org, CVS-committers@freefall.freebsd.org, cvs-sys@freefall.freebsd.org Subject: Re: cvs commit: src/sys/i386/isa syscons.c Message-ID: <199610270755.JAA17287@grumble.grondar.za>
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Bruce Evans wrote: > There seems to be a more serious problem with reentrancy in > add_timer_randomness(). It is called from interrupt handlers at the > ipls of the handlers, so it may be reentered. It doesn't seem to be > designed for this. I guess it works in Linux because it is always > called with interrupts disabled. It should use splhigh() in FreeBSD. > (Don't forget the design goal that interrupts should not be masked for > too long. 20 usec is too long.) Since it is normally (*) called from > the keyboard interrupt handler at ipl >= tty_imask, it is now only safe > to gather entropy for interrupts generated by tty-class devices. I have found bits of code that look like s = splhigh(); /* handle the interrupt */ splx(s); /* or spl0(); */ But the comments in spl.h are very unenlightening. :-( Please give me a short (english!) introduction as to what the @#$% is going on here :-). M -- Mark Murray 46 Harvey Rd, Claremont, Cape Town 7700, South Africa +27 21 61-3768 GMT+0200 Finger mark@grondar.za for PGP key
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