On Mon, Oct 01, 2001 at 10:56:24AM +0930, Greg Lehey wrote: > [Format recovered--see http://www.lemis.com/email/email-format.html] > > On Friday, 28 September 2001 at 10:12:14 -0700, Julian Elischer wrote: > > On Fri, 28 Sep 2001, Gersh wrote: > >> On Fri, 28 Sep 2001, Bernd Walter wrote: > >>> On Fri, Sep 28, 2001 at 07:03:51PM +0530, Anjali Kulkarni wrote: > >>>> Does anyone know whether it is advisable or not to use > >>>> setjmp/longjmp within kernel code? I could not see any > >>>> setjmp/longjmp in kernel source code. Is there a good reason for > >>>> this or can it be used? > >>> > >>> You need to look again, it's used in several places in the kernel. > >> > >> Look at sys/i386/i386/db_interface.c > > > > Yeah but it would probably be a pretty bad idea to use it without > > very careful thought. Especialy with the kernel becoming > > pre-emptable in the future.. > > Can you think of a scenario where it wouldn't work? Preemption > doesn't tear stacks apart, right?
How about a case of a longjmp() back from under an acquired lock/mutex? Like function A sets up a jump buffer, calls function B, B acquires a lock, B calls C, C longjmp()'s back to A; what happens to the lock? It would work if A were aware of B's lock and the possibility of a code path that would end up with it still being held; I presume that this is what Julian meant by 'very careful thought'. G'luck, Peter -- Do you think anybody has ever had *precisely this thought* before? To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
