Date: Mon, 18 Aug 2008 11:38:40 -0700 From: Julian Elischer <julian@elischer.org> To: Ed Maste <emaste@freebsd.org> Cc: freebsd-hackers@freebsd.org Subject: Re: Acquiring a mtx after an sx lock Message-ID: <48A9C1B0.5010805@elischer.org> In-Reply-To: <48A9BFED.604@elischer.org> References: <bc2d970808180814ue926d43s7966b36ffa3c9699@mail.gmail.com> <200808181754.18812.max@love2party.net> <bc2d970808180902h1ded9bcbp494d276ede0eeed@mail.gmail.com> <20080818162411.GA77460@sandvine.com> <48A9BFED.604@elischer.org>
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Julian Elischer wrote: > Ed Maste wrote: >> On Mon, Aug 18, 2008 at 12:02:56PM -0400, Ryan Stone wrote: >> >>> On Mon, Aug 18, 2008 at 11:54 AM, Max Laier <max@love2party.net> wrote: >>> >>>> On Monday 18 August 2008 17:14:01 Ryan Stone wrote: >>>>> Are there any problems acquiring a sleep mutex after acquiring an sx >>>> lock? >>>>> man 9 locking says that you can't, but doesn't provide any reasons. >>>> [...] >>>> >>>> Where does it say so? The interaction table clearly shows: [...] >> >> Ahh, it seems ups' commit of rmlocks changed the "You have: sx_lock, >> You want: Slp_mtx" case from no to ok (in r173444). > > > hmmm > you know, I'm not sure what the correct answer is.. I thought rw locks > were mutex compatible but sx locks were NOT.. Ignore me.. I was reading the table backwards.. of course if you have an sx you can still take out a mutex, but not visa versa. An sx lock is considered related to a sleep. (i.e. may be long term) and as such must not be taken out when holding a mutex, which must not sleep. > >> >> -Ed >> _______________________________________________ >> freebsd-hackers@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-hackers >> To unsubscribe, send any mail to >> "freebsd-hackers-unsubscribe@freebsd.org" > > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org"
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